Re: Topband: Effect of current max not at base of vertical.
Re signal improvements when over fresh water or swamp I've notice that many times on VHF or FM radio in the car and always simply suspected the effects of being in the clear without obstructions like buildings and trees. Pete W2PM -Original Message- From: ZR z...@jeremy.mv.com To: Guy Olinger K2AV olin...@bellsouth.net Cc: topband topband@contesting.com; herbs he...@vitelcom.net Sent: Sat, Sep 24, 2011 11:35 pm Subject: Re: Topband: Effect of current max not at base of vertical. Well, Im on top of a pine and oak covered hill these days and RF ground esistance tests say it aint so hot; about 250 Ohms for the Beverages. There is bout 8-10 of compost and then very bony soil to an average of 18 before solid ock. Now, the rock what locals call rotten granite as it just flakes off, is ikely due to a high iron content which also affects well water around here. Maybe I should try drilling deep into the rock and pounding down a copper clad od that is slightly larger diameter. I still remember driving around when much younger how suddenly the AM BCB would ave much increased signal strengths for a short distance and there was nothing isible in the area to account for it. Crossing over a large area of fresh water r swamp always peaked signals even when the road wasnt elevated. Answers are needed. Carl M1H - Original Message - From: Guy Olinger K2AV To: ZR Cc: he...@vitelcom.net ; topband@contesting.com Sent: Saturday, September 24, 2011 3:30 PM Subject: Re: Topband: Effect of current max not at base of vertical. EZNEC's fresh water selection shows a conductivity of .001 (very nconductive). So it's talking about Great Lakes fresh water away from urban olution. Question would be how conductive the swamp water is. I would ersonally guess that if the area is heavily vegetated and slow draining, the onductivity would be higher due to dissolved compounds produced by submerged otting vegetation. Anybody care to go out in the middle of your local freshwater swamp and stick hmmeter probes down there? The conductivity may even be layered, since the ater with dissolved materials will weigh more and the more fresh will lay on op. If really stinky fresh water marsh is as conductive as that super-rich idwest pastoral soil we keep hearing about, it jumps up to the best of on-salt-water results. How conductive is YOUR local fresh water swamp. 73, Guy PS, this also applies to fairly acidic recently wet down pine straw forest loors, like those down in flat land Carolina loblolly or oak forests. Would ary incredibly depending on whether dry or not, or well drained with acid eached out. On Sat, Sep 24, 2011 at 11:29 AM, ZR z...@jeremy.mv.com wrote: Ive doubted some of the claims about fresh water swamps based only on ersonal experience. At a prior QTH I had them on 2 sides and extending to a ile or more and the 160 vertical appeared to play better then expected. All that rotting vegetation had to be good for something and it rarely froze ore than a few inches in the winter. Carl KM1H -- No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1410 / Virus Database: 1520/3917 - Release Date: 09/24/11 __ R RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Effect of current max not at base of vertical
I onvce did a observational study like this with W2JPW who lives 3 miles from my QTH. We did the test on all bands from 160 to 2 meters using zero gain omni directional antennas. On 160, with 1500W he was S5. On 80 S9 plus, On 40 S4, and moderately strong on higher bands except for 17meters where he was very weak. All the time we were in QSO on a 2 meter 1.5W portable in each of our basements with rubber antennas. Full quieting each way. By the way on the weak bands he had no issues with QSO success on them so there wasnt anything inherently bad about his system. Pete W2PM -Original Message- From: W9UCW w9...@aol.com To: topband topband@contesting.com Sent: Sat, Sep 24, 2011 11:35 pm Subject: Re: Topband: Effect of current max not at base of vertical This may or may not be significant to the discussion. In the 1970's I was sing a 120 foot insulated base vertical as my main transmit antenna. I had 2,000 feet of #12 copper radials from 90 to 200 feet in length buried bout 3 inches in the ground surrounding the antenna. It was located near inooka, Illinois in a wooded rural area. s an experiment, I asked several friends who were located from one to welve miles away to record my signal strength at their location each day for ne month at a specific power of 100 watts of carrier. Then I had my tower limbing buddy, Jack, W9YF (SK) put a resonator tuned to 1850 on top of the ertical. had to modify the base matching system. It had been a shunt coil to round. It now required a parallel resonant circuit from the base of the tower o ground with the coax from the rig tapped onto the coil. hen my friends reported the signal strength they now recorded, it was rom a half to a full S unit more than their original readings. Now that's ertainly not very scientific, but their comments, assuming all groundwave eadings, were sure interesting to me. 3, CU on TopBand, Barry, W9UCW __ R RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Effect of current max not at base of vertical.
On Sat, Sep 24, 2011 at 3:30 PM, Guy Olinger K2AV olin...@bellsouth.net wrote: EZNEC's fresh water selection shows a conductivity of .001 (very unconductive). So it's talking about Great Lakes fresh water away from urban polution. Leaving the conductivity at 1mS/m and changing only the permittivity from 10 to 80 in a NEC-2 model of a 160m quarterwave over 20 78 foot radials gives a big boost to the low angle radiation. About 4dB improvement at 13 degrees and 7dB at 2 degrees. Anybody care to go out in the middle of your local freshwater swamp and stick ohmmeter probes down there? The conductivity may even be layered, since the water with dissolved materials will weigh more and the more fresh will lay on top. The USGS water data site might be an interesting resource. The stream near my house always averages between 30 and 60 mS/m (300 and 600 microsiemens per centimeter) for the past six years: http://goo.gl/7mE5m Urban pollution is certainly a potential issue here... but we can look around many sites. 30mS/m recently up in the Potomac up in West Virginia. Here's Lake Champlain @ Burlington VT (probably at an inlet?) http://goo.gl/TGSCK The conductance meters happen to be installed on the couple stations I care about for other reasons, but maybe not around the rest of the country. If you click a state and then choose build sequence, simply hit SUBMIT under Site Selection Criteria and check specific conductance and hit submit again you can find all the stations that have a conductance meter. I have yet to see anything as low as 1mS/m (10 microsiemens per cm) in spot checks. Found some in Georgia that went down to 5mS/m when it rained a lot. Anyway, just some thoughts. 73 Dan ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Effect of current max not at base of vertical.
Or driving around and the AM BCB got much louder when driving over a railroad track. I wonder what would happen if my radial system would be the tracks, only one since I don't want to trip the signal. But the train every hour would probably cause lots of issues, not to mention the railroad police. Never mind. Darl NA8W -- From: ZR z...@jeremy.mv.com Sent: Saturday, September 24, 2011 7:07 PM To: Guy Olinger K2AV olin...@bellsouth.net Cc: topband@contesting.com; he...@vitelcom.net Subject: Re: Topband: Effect of current max not at base of vertical. Well, Im on top of a pine and oak covered hill these days and RF ground resistance tests say it aint so hot; about 250 Ohms for the Beverages. There is about 8-10 of compost and then very bony soil to an average of 18 before solid rock. Now, the rock what locals call rotten granite as it just flakes off, is likely due to a high iron content which also affects well water around here. Maybe I should try drilling deep into the rock and pounding down a copper clad rod that is slightly larger diameter. I still remember driving around when much younger how suddenly the AM BCB would have much increased signal strengths for a short distance and there was nothing visible in the area to account for it. Crossing over a large area of fresh water or swamp always peaked signals even when the road wasnt elevated. Answers are needed. Carl KM1H - Original Message - From: Guy Olinger K2AV To: ZR Cc: he...@vitelcom.net ; topband@contesting.com Sent: Saturday, September 24, 2011 3:30 PM Subject: Re: Topband: Effect of current max not at base of vertical. EZNEC's fresh water selection shows a conductivity of .001 (very unconductive). So it's talking about Great Lakes fresh water away from urban polution. Question would be how conductive the swamp water is. I would personally guess that if the area is heavily vegetated and slow draining, the conductivity would be higher due to dissolved compounds produced by submerged rotting vegetation. Anybody care to go out in the middle of your local freshwater swamp and stick ohmmeter probes down there? The conductivity may even be layered, since the water with dissolved materials will weigh more and the more fresh will lay on top. If really stinky fresh water marsh is as conductive as that super-rich midwest pastoral soil we keep hearing about, it jumps up to the best of non-salt-water results. How conductive is YOUR local fresh water swamp. 73, Guy PS, this also applies to fairly acidic recently wet down pine straw forest floors, like those down in flat land Carolina loblolly or oak forests. Would vary incredibly depending on whether dry or not, or well drained with acid leached out. On Sat, Sep 24, 2011 at 11:29 AM, ZR z...@jeremy.mv.com wrote: Ive doubted some of the claims about fresh water swamps based only on personal experience. At a prior QTH I had them on 2 sides and extending to a mile or more and the 160 vertical appeared to play better then expected. All that rotting vegetation had to be good for something and it rarely froze more than a few inches in the winter. Carl KM1H -- No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1410 / Virus Database: 1520/3917 - Release Date: 09/24/11 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Effect of current max not at base of vertical.
George, Some designs have been able to reduce the over all height of the Franklin by folding out or back the high voltage top and bottom portions. The phasing coupler is placed at the center with the transmission line inside the insulated bottom section. The center feed portion with a correct phase reversal is supposed to be crucial to proper operation. WHO KSTP used Franklin antennas because they were by assignment omni directional 50KW stations that wanted a bit more ERP and a multi tower directional was not an option. For hams this could easily be done with a Z type configuration with a top wire and a bottom wire bringing the whole antenna to a two half waves in phase array, assuming the center coupler thus exceeding the gain at low angles well over a single bottom fed half wave radiator. A folded Franklin might be easy to model to determine the point of diminishing return on the folded portion. Herb, KV4FZ On 9/23/2011 5:22 PM, GeorgeWallner wrote: Herb, I have just looked it up. Interesting. For 160 the height would be tad excessive. TKS, George, AA7JV On Fri, 23 Sep 2011 01:21:39 -0400 Herb Schoenbohm he...@vitelcom.net wrote: George, Are you familiar with the Franklyn antenna design? Some broadcasters swear by them and claim a 3 db increase over a 1/4 vertical radiator. Herb, KV4FZ On 9/22/2011 9:08 PM, GeorgeWallner wrote: On Tue, 20 Sep 2011 17:17:58 -0400 Guy Olinger K2AVolin...@bellsouth.net wrote: I share the frustration over the very minimal amount of data out there. However... Erection of a 260 foot vertical in a testing environment... G'Day Topbanders, I am not sure how general a conclusions could be drawn from my experience, but I have a set up that is somewhat relevant to this thread, and have done some on the air testing with it. I have two verticals, about 2 meters apart. One is 21 meters tall and the other one is 28 meters tall with a high Q center loading inductor to make it resonate at 1900 kHz (this is my 160 m antenna). This antenna is fed via a low loss antenna coupler. The two antennas share a common ground system, which is salt-water to the east and a buried field of 40 radials of varying length between 30 and 120 feet long to the west. On 80 meters the shorter antenna is a 1/4 wave vertical, while the longer one could be considered to be a half-wave vertical. I have done extensive tests on 80 meters, comparing the two antennas towards the east. I have used the reverse beacon network, and a couple of friends' SDR-s in Europe for these comparisons. In tests from my Florida QTH, towards the east (towards Europe) and the side where the salt water is, the taller antenna has almost always been better by 2 to 3 dB. Towards the west (and the land side) I have not done enough testing to draw conclusive results, but I feel that the 1/2 wave vertical is better in that direction too. I understand the 80 meters is not 160 meters, but... I would be happy to set up a test sched with anyone to my west or north-west, who is interested in carrying these studies further. 73, George, AA7JV PS: BTW, I almost always use the 1/4 vertical on 80 meters, even towards the east, as going through the coupler is a PITA (as Guy has pointed out). ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Effect of current max not at base of vertical.
I don't really know for sure. But from modeling it and the article, I suspect not. He only talks about lack of 50 kW capable low Z strapping down to a radial field. He doesn't specifically say *no* ground screen. I suspect there is something directly underneath each of the monopoles, but I don't know that. There should be something in the magnitude of 700 volts/meter RMS field directly underneath and over 25 V/m inside a 50' radius. Would think that would they would do something right underneath for to keep from setting stuff on fire. One other antenna I know of that is a low-end-of-the-BC-band vertical halfwave fed in the center (with the same issue near the ground) has a heavy screened cage directly underneath. The modeled field drops very rapidly from the maximum 700 V/m directly underneath to 250 at 10 feet, 81 at 25 feet, to 28 at 50 feet to reach a minimum of about 8 V/m out 100 feet then gradually back up to 15 V/m out around 400 feet and then very gradually drops to 3.88 V/m at one mile. This is remarkably close to the measured 3.55 quoted in the article. The 400 feet would be the maximum loss pattern intercept of the ground, and getting beyond typical radial fields for 1/4 wave verticals at this frequency. Since the model without any screening is slightly better than their measured, the odds are no screening. Don't want to get near the base of that thing running with anything metal on you. Set yourself on fire. 73, Guy. On Fri, Sep 23, 2011 at 6:45 PM, Milt -- N5IA n...@zia-connection.comwrote: Guy, Do I read the article correctly that there is little grounding and no radial screen under these monsters. Is that correct? Milt, N5IA -Original Message- From: Guy Olinger K2AV Sent: Friday, September 23, 2011 1:43 PM To: he...@vitelcom.net Cc: topband@contesting.com Subject: Re: Topband: Effect of current max not at base of vertical. See http://www.fybush.com/sites/**2005/site-051028.htmlhttp://www.fybush.com/sites/2005/site-051028.html For 1530 kHz, that's a PAIR of two vertical halfwaves in phase. 50 kW gives 3545.89 mV/m. Note the relative lack of neighbors, and therefore lack of 24 hour miscellaneous diodic signal demodulation, talking window screens, permanently lit florescent bulbs, etc. Note that this monster is not too far from 160m. Think big and put an only slightly downsized 160 version out in the salt shallows somewhere on the western side of Cheasapeake Bay. Without any controversy whatsoever as to ground induction losses (zero) EZNEC says this would put 13.6 dbi gain toward Europe at 3.1 degree takeoff. Order of magnitude: three element yagi. Just for comparison, if I drain Chesapeake Bay and fill it with concrete rubble and other urban debris (can do magical things in EZNEC) I get 5.0 dbi at 12.9 degrees. The full table: Urban debris: 5.0 @ 12.9d Sandy 4.8 @ 10.7d Rocky, poor5.2 @ 10.6d On Fri, Sep 23, 2011 at 1:21 AM, Herb Schoenbohm he...@vitelcom.net wrote: George, Are you familiar with the Franklyn antenna design? Some broadcasters swear by them and claim a 3 db increase over a 1/4 vertical radiator. __**_ UR RST IS ... ... ..9 QSB QSB - hw? BK - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1410 / Virus Database: 1520/3914 - Release Date: 09/23/11 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Effect of current max not at base of vertical.
Ive doubted some of the claims about fresh water swamps based only on personal experience. At a prior QTH I had them on 2 sides and extending to a mile or more and the 160 vertical appeared to play better then expected. All that rotting vegetation had to be good for something and it rarely froze more than a few inches in the winter. Carl KM1H - Original Message - From: Guy Olinger K2AV olin...@bellsouth.net To: he...@vitelcom.net Cc: topband@contesting.com Sent: Friday, September 23, 2011 5:37 PM Subject: Re: Topband: Effect of current max not at base of vertical. Apologize for earlier half-done post. Spastic hit on send key. See http://www.fybush.com/sites/2005/site-051028.html for a Franklin and a nice article. For 1530 kHz, that's a *pair* of two vertical halfwaves in phase. 50 kW gives 3545.89 mV/m for broadcasting purposes. Note the relative lack of neighbors, and therefore lack of 24 hour miscellaneous diodic signal demodulation, talking window screens, permanently lit florescent bulbs, etc. Note that this monster is not too far from 160m. Think big and put an only slightly downsized 160 version out in the salt shallows somewhere on the western side of Cheasapeake Bay. Without any controversy whatsoever as to ground induction losses (zero) EZNEC says this would put 13.6 dbi gain toward Europe at 3.1 degree takeoff. Order of magnitude: three element yagi. Just for comparison, if I drain Chesapeake Bay and fill it with concrete rubble and other urban debris (can do magical things in EZNEC) I get 5.0 dbi at 12.9 degrees. The full EZNEC preloaded table follows, filling Chesapeake Bay with other dirt, or turning it into a fresh water lake. These figures are *without* any ground field copper underneath, as it is not needed for a current sink and I have no data on what kind of field might actually be employed. Urban debris: 5.0 @ 12.9d (-5.0 dB from that angle takeoff over seawater) Sandy 4.8 @ 10.7d (-6.6) Rocky, poor5.2 @ 10.6d (-6.2) Average5.4 @ 9.0d (-6.8) Forest 5.7 @ 8.7d (-6.6) Marshy 6.1 @ 8.4d (-6.0) Rich pastoral 6.8 @ 8.1d (-5.8) Very rich 9.1 @ 7.1d (-3.8) Fresh water8.4 @ 8.9d (-3.8) Salt water13.6 @ 3.1d (0) One can dream. 73, Guy. On Fri, Sep 23, 2011 at 1:21 AM, Herb Schoenbohm he...@vitelcom.net wrote: George, Are you familiar with the Franklyn antenna design? Some broadcasters swear by them and claim a 3 db increase over a 1/4 vertical radiator. Herb, KV4FZ ___ UR RST IS ... ... ..9 QSB QSB - hw? BK - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1410 / Virus Database: 1520/3916 - Release Date: 09/24/11 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Effect of current max not at base of vertical.
EZNEC's fresh water selection shows a conductivity of .001 (very unconductive). So it's talking about Great Lakes fresh water away from urban polution. Question would be how conductive the swamp water is. I would personally guess that if the area is heavily vegetated and slow draining, the conductivity would be higher due to dissolved compounds produced by submerged rotting vegetation. Anybody care to go out in the middle of your local freshwater swamp and stick ohmmeter probes down there? The conductivity may even be layered, since the water with dissolved materials will weigh more and the more fresh will lay on top. If really stinky fresh water marsh is as conductive as that super-rich midwest pastoral soil we keep hearing about, it jumps up to the best of non-salt-water results. How conductive is YOUR local fresh water swamp. 73, Guy PS, this also applies to fairly acidic recently wet down pine straw forest floors, like those down in flat land Carolina loblolly or oak forests. Would vary incredibly depending on whether dry or not, or well drained with acid leached out. On Sat, Sep 24, 2011 at 11:29 AM, ZR z...@jeremy.mv.com wrote: Ive doubted some of the claims about fresh water swamps based only on personal experience. At a prior QTH I had them on 2 sides and extending to a mile or more and the 160 vertical appeared to play better then expected. All that rotting vegetation had to be good for something and it rarely froze more than a few inches in the winter. Carl KM1H ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Effect of current max not at base of vertical.
Well, Im on top of a pine and oak covered hill these days and RF ground resistance tests say it aint so hot; about 250 Ohms for the Beverages. There is about 8-10 of compost and then very bony soil to an average of 18 before solid rock. Now, the rock what locals call rotten granite as it just flakes off, is likely due to a high iron content which also affects well water around here. Maybe I should try drilling deep into the rock and pounding down a copper clad rod that is slightly larger diameter. I still remember driving around when much younger how suddenly the AM BCB would have much increased signal strengths for a short distance and there was nothing visible in the area to account for it. Crossing over a large area of fresh water or swamp always peaked signals even when the road wasnt elevated. Answers are needed. Carl KM1H - Original Message - From: Guy Olinger K2AV To: ZR Cc: he...@vitelcom.net ; topband@contesting.com Sent: Saturday, September 24, 2011 3:30 PM Subject: Re: Topband: Effect of current max not at base of vertical. EZNEC's fresh water selection shows a conductivity of .001 (very unconductive). So it's talking about Great Lakes fresh water away from urban polution. Question would be how conductive the swamp water is. I would personally guess that if the area is heavily vegetated and slow draining, the conductivity would be higher due to dissolved compounds produced by submerged rotting vegetation. Anybody care to go out in the middle of your local freshwater swamp and stick ohmmeter probes down there? The conductivity may even be layered, since the water with dissolved materials will weigh more and the more fresh will lay on top. If really stinky fresh water marsh is as conductive as that super-rich midwest pastoral soil we keep hearing about, it jumps up to the best of non-salt-water results. How conductive is YOUR local fresh water swamp. 73, Guy PS, this also applies to fairly acidic recently wet down pine straw forest floors, like those down in flat land Carolina loblolly or oak forests. Would vary incredibly depending on whether dry or not, or well drained with acid leached out. On Sat, Sep 24, 2011 at 11:29 AM, ZR z...@jeremy.mv.com wrote: Ive doubted some of the claims about fresh water swamps based only on personal experience. At a prior QTH I had them on 2 sides and extending to a mile or more and the 160 vertical appeared to play better then expected. All that rotting vegetation had to be good for something and it rarely froze more than a few inches in the winter. Carl KM1H -- No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1410 / Virus Database: 1520/3917 - Release Date: 09/24/11 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Effect of current max not at base of vertical
This may or may not be significant to the discussion. In the 1970's I was using a 120 foot insulated base vertical as my main transmit antenna. I had 12,000 feet of #12 copper radials from 90 to 200 feet in length buried about 3 inches in the ground surrounding the antenna. It was located near Minooka, Illinois in a wooded rural area. As an experiment, I asked several friends who were located from one to twelve miles away to record my signal strength at their location each day for one month at a specific power of 100 watts of carrier. Then I had my tower climbing buddy, Jack, W9YF (SK) put a resonator tuned to 1850 on top of the vertical. I had to modify the base matching system. It had been a shunt coil to ground. It now required a parallel resonant circuit from the base of the tower to ground with the coax from the rig tapped onto the coil. When my friends reported the signal strength they now recorded, it was from a half to a full S unit more than their original readings. Now that's certainly not very scientific, but their comments, assuming all groundwave readings, were sure interesting to me. 73, CU on TopBand, Barry, W9UCW ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Effect of current max not at base of vertical.
George, Are you familiar with the Franklyn antenna design? Some broadcasters swear by them and claim a 3 db increase over a 1/4 vertical radiator. Herb, KV4FZ On 9/22/2011 9:08 PM, GeorgeWallner wrote: On Tue, 20 Sep 2011 17:17:58 -0400 Guy Olinger K2AVolin...@bellsouth.net wrote: I share the frustration over the very minimal amount of data out there. However... Erection of a 260 foot vertical in a testing environment... G'Day Topbanders, I am not sure how general a conclusions could be drawn from my experience, but I have a set up that is somewhat relevant to this thread, and have done some on the air testing with it. I have two verticals, about 2 meters apart. One is 21 meters tall and the other one is 28 meters tall with a high Q center loading inductor to make it resonate at 1900 kHz (this is my 160 m antenna). This antenna is fed via a low loss antenna coupler. The two antennas share a common ground system, which is salt-water to the east and a buried field of 40 radials of varying length between 30 and 120 feet long to the west. On 80 meters the shorter antenna is a 1/4 wave vertical, while the longer one could be considered to be a half-wave vertical. I have done extensive tests on 80 meters, comparing the two antennas towards the east. I have used the reverse beacon network, and a couple of friends' SDR-s in Europe for these comparisons. In tests from my Florida QTH, towards the east (towards Europe) and the side where the salt water is, the taller antenna has almost always been better by 2 to 3 dB. Towards the west (and the land side) I have not done enough testing to draw conclusive results, but I feel that the 1/2 wave vertical is better in that direction too. I understand the 80 meters is not 160 meters, but... I would be happy to set up a test sched with anyone to my west or north-west, who is interested in carrying these studies further. 73, George, AA7JV PS: BTW, I almost always use the 1/4 vertical on 80 meters, even towards the east, as going through the coupler is a PITA (as Guy has pointed out). ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Effect of current max not at base of vertical.
See http://www.fybush.com/sites/2005/site-051028.html For 1530 kHz, that's a PAIR of two vertical halfwaves in phase. 50 kW gives 3545.89 mV/m. Note the relative lack of neighbors, and therefore lack of 24 hour miscellaneous diodic signal demodulation, talking window screens, permanently lit florescent bulbs, etc. Note that this monster is not too far from 160m. Think big and put an only slightly downsized 160 version out in the salt shallows somewhere on the western side of Cheasapeake Bay. Without any controversy whatsoever as to ground induction losses (zero) EZNEC says this would put 13.6 dbi gain toward Europe at 3.1 degree takeoff. Order of magnitude: three element yagi. Just for comparison, if I drain Chesapeake Bay and fill it with concrete rubble and other urban debris (can do magical things in EZNEC) I get 5.0 dbi at 12.9 degrees. The full table: Urban debris: 5.0 @ 12.9d Sandy 4.8 @ 10.7d Rocky, poor5.2 @ 10.6d On Fri, Sep 23, 2011 at 1:21 AM, Herb Schoenbohm he...@vitelcom.net wrote: George, Are you familiar with the Franklyn antenna design? Some broadcasters swear by them and claim a 3 db increase over a 1/4 vertical radiator. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Effect of current max not at base of vertical.
On Tue, 20 Sep 2011 17:17:58 -0400 Guy Olinger K2AV olin...@bellsouth.net wrote: I share the frustration over the very minimal amount of data out there. However... Erection of a 260 foot vertical in a testing environment... G'Day Topbanders, I am not sure how general a conclusions could be drawn from my experience, but I have a set up that is somewhat relevant to this thread, and have done some on the air testing with it. I have two verticals, about 2 meters apart. One is 21 meters tall and the other one is 28 meters tall with a high Q center loading inductor to make it resonate at 1900 kHz (this is my 160 m antenna). This antenna is fed via a low loss antenna coupler. The two antennas share a common ground system, which is salt-water to the east and a buried field of 40 radials of varying length between 30 and 120 feet long to the west. On 80 meters the shorter antenna is a 1/4 wave vertical, while the longer one could be considered to be a half-wave vertical. I have done extensive tests on 80 meters, comparing the two antennas towards the east. I have used the reverse beacon network, and a couple of friends' SDR-s in Europe for these comparisons. In tests from my Florida QTH, towards the east (towards Europe) and the side where the salt water is, the taller antenna has almost always been better by 2 to 3 dB. Towards the west (and the land side) I have not done enough testing to draw conclusive results, but I feel that the 1/2 wave vertical is better in that direction too. I understand the 80 meters is not 160 meters, but... I would be happy to set up a test sched with anyone to my west or north-west, who is interested in carrying these studies further. 73, George, AA7JV PS: BTW, I almost always use the 1/4 vertical on 80 meters, even towards the east, as going through the coupler is a PITA (as Guy has pointed out). ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Effect of current max not at base of vertical.
On 9/20/2011 2:17 PM, Guy Olinger K2AV wrote: I share the frustration over the very minimal amount of data out there. However... Erection of a 260 foot vertical in a testing environment fairly well requires the facilities of a large antenna range to do the comparisons below. Thus we are also talking about money, and we are talking about a subject where all the pressing *commercial *questions have been answered for nearly a century. We are also talking about research that was done 1920 to 1940, well outside the time of electronic media and as far as I can tell never converted, again an expensive task with no commercial or government money to pay for grad students digging it up and putting it on the internet. How would one justify the grant money? Besides that, who do you know putting up a 260 foot vertical? Why are we even talking about that? W8JI has done that. He would :)Who else? Does Warren Buffet have a ham license? How does a 260 foot vertical stack Nonsense. For research purposes, just put up a balloon vertical on a calm day in some remote area. Set up a transmit source a mile away and compare received signal strength vs height. Temporarily roll out some radials. I could do this test at my own QTH of 20 acres and I'm no Warren Buffett (land is cheap where I am). I could test the balloon vertical over my big ground screen and then move it away from the ground screen and retest. Maybe someday when I have the time... BTW, the complete Proceedings of the IRE back to before 1920 are online at the IEEE now. Laporte's book is now available as a pdf. Rick N6RK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Effect of current max not at base of vertical.
On 09/17/2011 01:19 PM, Richard (Rick) Karlquist wrote: I'm still waiting to see an actual measurement showing that a 1/2 wave vertical with minimal radials is worse than a 1/4 wave vertical with radials. My measurements were over high conductivity ground. Maybe they would be different in the desert. That's hard to imagine. A 1/2 wave vertical without any radials at all is only a few dB (2-6 depending on ground type and exact antenna shape) below that of a 1/4 wave vertical over totally perfect ground. I'm sure a 1/4 wave vertical with 8 raised radials, all raised maybe 10-20ft above ground, would be better still - but only by a few dB and it'd take up a lot more real estate... -- All rights reversed. ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Effect of current max not at base of vertical.
With commercial field strength meters being fairly available on the used market it would be one way to end the arguments with things that are purely speculative. Carl KM1H - Original Message - From: Rick Stealey rstea...@hotmail.com To: topband@contesting.com Sent: Monday, September 19, 2011 12:45 PM Subject: Re: Topband: Effect of current max not at base of vertical. Milt says: Yet we all know from experience that the WWV radiation performance is excellent. I see N6RK has addressed this statement in his response as well, but I would like to add that this kind of statement is often heard on the air, That antenna of yours there is doing a FB job for you. I always think, How do you know? Maybe his antenna is working horribly. Maybe the owner has water in his coax, and a resultant 10 db of loss, but the propagation just happens to be favorable and he is really putting a smashing signal into your QTH in spite of his 10 db loss. Turn the thought process around a bit, and ask ANY ham you talk to how he likes his antenna, how's it working for him? Invariably he will tell you it works great, he loves it. Ask him how he knows it is working great and he will tell you, Because of all the stations I work, who tell me what a great signal I have!!!' Think about it. Rick K2XT ___ UR RST IS ... ... ..9 QSB QSB - hw? BK - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1410 / Virus Database: 1520/3907 - Release Date: 09/19/11 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Effect of current max not at base of vertical.
I share the frustration over the very minimal amount of data out there. However... Erection of a 260 foot vertical in a testing environment fairly well requires the facilities of a large antenna range to do the comparisons below. Thus we are also talking about money, and we are talking about a subject where all the pressing *commercial *questions have been answered for nearly a century. We are also talking about research that was done 1920 to 1940, well outside the time of electronic media and as far as I can tell never converted, again an expensive task with no commercial or government money to pay for grad students digging it up and putting it on the internet. How would one justify the grant money? Besides that, who do you know putting up a 260 foot vertical? Why are we even talking about that? W8JI has done that. He would :)Who else? Does Warren Buffet have a ham license? How does a 260 foot vertical stack up against HOA restrictions. That's FAA tower listing territory in metropolitan areas, or near any airport. Lighting requirements. Six acres for the tower and guys. Back to the realm of the possible for common folk There is an EZNEC issue in *modeling* (vs measuring) ground effects: Measured ground induction losses in situations *not *using radials, or* less than dense* or *miscellaneous* radials, on the whole can be significantly*worse *than modeling would anticipate. Roy Lewallen W7EL, author of EZNEC, will confirm this, and will also state that the ground *estimation *method in use cannot cope with dirt with layered characteristics. The ground method presumes a monolithic, uniform substance, with no changes in moisture, no changes in anything, proceeding to depth where current is no longer significant. The lower frequency penetrates deeper. Deep enough that you find old Bell Labs stuff about *underground *antennas that apparently worked at LF, presumably only used for RX, but I don't know that. In typical ham property this brings items into play such as buried electric cables, buried iron or steel gas or water pipes, water tables, septic fields, actual layering in different soil materials from ancient events and weathering over stream beds. In the vicinity of my QTH this brings into play a layer of heavily carbonized clay from what was probably a forest fire before human history. It also includes such things as fill dirt with concrete or road debris used to level out property before building and then covered with a nice layer of good dirt suitable for plants, trees, grass, etc. And if that's not enough, then there is variation in moisture content, where soil is at 100% humidity down three, four, five feet where the temperature of dirt goes to the standard ground temperature for an area (the temperature in caves, etc.), even in a drought. Typical dirt underfoot is anything *except * monolithic. In EZNEC one can enter the conductivity (S/m) and dielectric constant directly, assuming you have the stuff to measure that, and the time to verify that is constant all over your property, *or *you can pick from the following choices, beginning with awful squared and progressing to the very best. Extremely Poor: cities, high bldgs. Very Poor: cities industrial. Sandy, dry Poor: rocky, mountainous Average: pastoral, heavy clay Pastoral, med hills and forestation Flat, marshy, densely wooded Pastoral, rich soil, US Midwest Very Good pastoral, rich central US Fresh water ** Salt water (** Fresh water is a special case that does not fit on the spectrum from least conductive to most conductive. If it were arranged by conductivity only, it would go with extremely poor. The dielectric constant is the same as salt water.) Why list these? Around Raleigh we had an experiment with 151' insulated dipoles laying directly on the dirt, finding their resonant frequencies, and feed resistance at resonance, and change from resonance at +/- 50 kHz from resonance. It was first an experiment to determine typical velocity factors for creating BOG RX antennas (beverage on ground). The other ramifications were realized later. The results were unbelievably variable, with measured velocity factor from 45% to 80%. In some cases varying wildly by position or orientation on the same property. THIS is what we're trying to estimate with a monolithic method in EZNEC. With just a few exceptions, when put in EZNEC and the ground characteristics adjusted to get the model to produce the measured results, it took poor and very poor ground settings to get it to match to any decent degree. This means that induced current in the dirt is indirectly *measured* far more lossy on average than we expect based on our looking at the EZNEC ground choices and descriptions. Dense radials shield us (significantly but not completely) from those effects where the E fields are the strongest, without them we underestimate the losses. Also from the dinner plate example, the cost of of seeing the floor from the light
Re: Topband: Effect of current max not at base of vertical.
Date: Sat, 17 Sep 2011 17:38:09 -0500 From: mikew...@gmail.com To: topband@contesting.com Subject: Re: Topband: Effect of current max not at base of vertical. Guy, I'm not saying that I understand this 100%, but I certainly do find it fascinating. I have a question, though. For quite some time, my understanding has been that by making a bottom-fed vertical (or inverted-L) longer than 1/4λ --and thereby raising the max current point-- that we simply move the point of maximum current farther out on the radials. This makes sense to me, if we consider the thought that the ground is an image of the antenna, the missing portion (for lack of a better expression). Other well-respected hams used to say that this condition significantly added to the requirements for the radial system under such a longer vertical in such a way that we now need even longer radials. Later, though, one of these hams seems to have reversed his beliefs 180°. I don't pretend to know the answer. (And at this point, I'm not sure anyone does. :-) If I use a 5/16λ or 3/8λ inverted-L, how does this change the requirements of: 1. ~60 radials stapled to the surface of the earth ? 2. An elevated counterpoise (which would of course require far fewer radials) ? Thanks, Mike www.w0btu.com I have the same issue and opinion that Mike describes, although my thoughts on how to deal with it are different. The point of difference is that I just don't want to put my hand in a bag of snakes fussing with the erection and tuning of elevated radials that in my case must weave around trees within a wooded area. My inverted L is 85' up and 85' out in the belief that its point of maximum current is located half way up the vertical leg. There are 55 in-ground radials, most of them 120-160 feet long (a dozen are only 75' long). My thought is that instead of adding more radials originating at the base feedpoint and extending each of them out 120-160 feet, there would be economies of copper and labor to crow foot those additional radials. By crow foot, I mean digging up an existing radial at, say, 60 feet out from the base feedpoint and splicing in a new radial that would fit within the interstice of two existing radials and would itself be only 60-100 feet long. And, by extension, repeating this crow footing at, say, another 30 feet away, splicing and siting each new radial between pairs of then-existing radials. As such, the newest radials would be only 30-70 feet long By this means I would avoid what I judge to be an unnecessary intensification of radial density close to the feedpoint, and instead deploy the copper further away and at areas where the existing radials are extremely far apart from one another. Charles, W2SH ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Effect of current max not at base of vertical.
Milt says: Yet we all know from experience that the WWV radiation performance is excellent. I see N6RK has addressed this statement in his response as well, but I would like to add that this kind of statement is often heard on the air, That antenna of yours there is doing a FB job for you. I always think, How do you know? Maybe his antenna is working horribly. Maybe the owner has water in his coax, and a resultant 10 db of loss, but the propagation just happens to be favorable and he is really putting a smashing signal into your QTH in spite of his 10 db loss. Turn the thought process around a bit, and ask ANY ham you talk to how he likes his antenna, how's it working for him? Invariably he will tell you it works great, he loves it. Ask him how he knows it is working great and he will tell you, Because of all the stations I work, who tell me what a great signal I have!!!' Think about it. Rick K2XT ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Effect of current max not at base of vertical.
While I was in College I had a ½ wave 20 meter vertical on the top of a two story apartment building. Fed with a parallel tuned circuit taped at the 50 ohm point with about 20 or so 18 foot radials. Worked like gang busters but I always had to wait in line to work rare DX. It was not the best but something better than the Ed Sullivan Show. But I did see the Beatles for the first time 73 Hardy N7RT - Original Message - From: Rick Stealey rstea...@hotmail.com To: topband@contesting.com Sent: Monday, September 19, 2011 9:45 AM Subject: Re: Topband: Effect of current max not at base of vertical. Milt says: Yet we all know from experience that the WWV radiation performance is excellent. I see N6RK has addressed this statement in his response as well, but I would like to add that this kind of statement is often heard on the air, That antenna of yours there is doing a FB job for you. I always think, How do you know? Maybe his antenna is working horribly. Maybe the owner has water in his coax, and a resultant 10 db of loss, but the propagation just happens to be favorable and he is really putting a smashing signal into your QTH in spite of his 10 db loss. Turn the thought process around a bit, and ask ANY ham you talk to how he likes his antenna, how's it working for him? Invariably he will tell you it works great, he loves it. Ask him how he knows it is working great and he will tell you, Because of all the stations I work, who tell me what a great signal I have!!!' Think about it. Rick K2XT ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Effect of current max not at base of vertical.
This is a lot mushier for buried radials, but the simple case for elevated radials is that the standing waves are set by the distance of the end of the radials from the radial feed, just like it is on a dipole. The end of an elevated radial MUST be the zero current, high voltage controlling point of the radial. I have not found the ground image mental simplifying device to be at all useful. You will find that only a couple certain ideal cases match the behavior suggested by the image. Personally, I've ditched the ground image as a useful concept for any situation I can afford on HF and down. If you can copper-plate a meadow somewhere, it will work for you. If you can swing that, I have some investment opportunities for you :) The real trick with a lot of this is to force these mental simplification devices to deal accurately with losses that MUST be there. Losses in the dirt are there. ACCOUNT for them accurately and what is left after the shakedown starts to make sense. 73, Guy. 2011/9/17 Mike Waters mikew...@gmail.com Guy, I'm not saying that I understand this 100%, but I certainly do find it fascinating. I have a question, though. For quite some time, my understanding has been that by making a bottom-fed vertical (or inverted-L) longer than 1/4λ --and thereby raising the max current point-- that we simply move the point of maximum current farther out on the radials. This makes sense to me, if we consider the thought that the ground is an image of the antenna, the missing portion (for lack of a better expression). Other well-respected hams used to say that this condition significantly added to the requirements for the radial system under such a longer vertical in such a way that we now need even longer radials. Later, though, one of these hams seems to have reversed his beliefs 180°. I don't pretend to know the answer. (And at this point, I'm not sure anyone does. :-) If I use a 5/16λ or 3/8λ inverted-L, how does this change the requirements of: 1. ~60 radials stapled to the surface of the earth ? 2. An elevated counterpoise (which would of course require far fewer radials) ? Thanks, Mike www.w0btu.com On Fri, Sep 16, 2011 at 11:03 AM, Guy Olinger K2AV olin...@bellsouth.netwrote: This is an answer to an off reflector conversation, relating to a too long electrical length over radials reducing performance. I am writing to the [snip] ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: Effect of current max not at base of vertical.
This is an answer to an off reflector conversation, relating to a too long electrical length over radials reducing performance. I am writing to the list since the subject and it's objection occur in so many posted conversations. Reduction of gain by too high current max has been touted by some and called myth by others. The reduction applies in fairly NARROW circumstances, which I think explains the APPEARANCE of myth. Used in certain other circumstances, raising of the current center on the vertical IMPROVES the results. The confusion comes from trying to lump divergent circumstances together, to run the equation with too few variables. If the vertical run plus the T (or an L) exceeds an electrical quarter wavelength, the current maximum will begin to rise away from the base of the antenna. Some designs deliberately put the current max well up the vertical. What is it that goes on? Let us begin with a WAY overkill, gold standard 1/4 wave vertical with 120 uniformly spaced 125' elevated radials at eight feet. This will work very, very well, little disagreement on that. There is deserved argument about where LOSS of performance kicks in as the number of radials is reduced and/or made non-uniform in length or spacing. And there is deserved argument about the DEGREE of loss in such circumstances. The NECx series of modeling programs underestimate that loss, how much depending on ground factors (what kind of dirt) that are difficult to measure. In many cases practically speaking these factors are unmeasurable unless one wants to dig up the back yard to measure them. The above gold-standard vertical will present a very predictable measured gain. It does present the very best avoidance of induced current-in-dirt losses, assuming the dirt is not a salt water marsh. So therefore one can expect that only REDUCTION in efficiency is possible from here. This IS assuming we are talking about overall efficiency, NOT measuring gain at a SINGLE takeoff angle (pattern changes). Part of the excellent performance of that antenna has to do with the radials' cancellation of the RF fields headed toward the ground immediately underneath. This is so because along the radials, the shape of the current is a very even exact opposite of the current in the vertical wire. The current maximum on BOTH the radials and the vertical wire are equal at the feedpoint and reduce in equal proportion moving away from the feedpoint. This means that the sum of the RF fields from vertical and radials are hugely MINIMIZED below the radials, EVEN THOUGH in this configuration, the current maximum in the vertical is as low, as close to the dirt, as it can be. The cancellation effectively makes the lossy dirt under the radials close to invisible, and forces the energy, that otherwise WOULD have been dissipated as heat in the dirt underneath, to be spent as useful radiation at other, more useful angles of radiation. It also has the maximum circle of cancellation. An exercise for illustration: elements are a dark room with a dark floor, an inch thick book, a circular white dinner plate, and a small non-focusing flashlight bulb. Put the book flat on the floor. Put the plate on top of the book. Turn on the bulb and hold it just touching the center of the plate and note the circle of darkness. Then raise the bulb and note the circle of darkness shrinking. Vertical radiation aimed at a non-sea-water ground surface is effectively lost. The vertical, although this is a very imprecise analogy, has a similar issue with raising the current center as the cancellation under the radials is gradually lost as the current center is raised. There is no complete vertical-radial field cancellation shadow as with the plate and flashlight, but gradual deepening of shadow toward the center. The more shadow, the less loss. Because of the inverse cube behavior of magnetic fields, the degree of cancellation is reduced much more quickly, counter-intuitively, as the current center is raised. AND THEN the RADIALS are now inducing fields down at the dirt which are no longer balanced by the REDUCED opposite phase field from the vertical. The performance *IS* reduced by the increasingly UNCANCELLED current in the RADIALS inducing lossy current in the ground. Now let us move away from our ideal to the much more common back yard that has zero chance of supporting a DENSE and efficient radial system. If a dense radial field cannot be done, then TO START WITH there was NOT the degree of possible cancellation under the radials to UNDO, and at some degree of sparse, or with no radials, RAISING the current center NOW IMPROVES performance. This is because near magnetic fields return their energy as the field collapses if they are not dissipated in close resistive conductors within the field (e.g. dirt), allowing the energy to be dissipated elsewhere. Therefore, in sparse radial or no-radial situations like the 5/16 wavelength single wire folded counterpoise,
Re: Topband: Effect of current max not at base of vertical.
-Original Message- From: Guy Olinger K2AV Sent: Friday, September 16, 2011 9:03 AM To: TopBand List Subject: Topband: Effect of current max not at base of vertical. This is an answer to an off reflector conversation, relating to a too long electrical length over radials reducing performance. I am writing to the list since the subject and it's objection occur in so many posted conversations. Reduction of gain by too high current max has been touted by some and called myth by others. -- OK Guy, Please explain in a comparative sense to the examples presented in your post, the 1/2 wavelength verticals (vertical dipoles) used at WWV where the maximum current is raised to near 3/8 WL AGL. Inquiring minds would like to know why WWV would utilize this configuration of vertically polarized antenna vs the Gold Standard 1/4 WL you describe. It would seem the illumination of the ground from the center fed 1/2 WL vertical dipole would present an extreme example of additional ground losses. Yet we all know from experience that the WWV radiation performance is excellent. Thanks for your time in making this requested comparison and presenting your view. Milt, N5IA ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
