Re: Topband: circular polarization on 160m
All, Bah, humbug. We got another 5 inches of snow overnight. We're running out of room to put the snow. At least I can stay inside and play on the radio. Tom makes some good points. Two comments. First, when I said advantage, all I meant was there is less fading on HF when receiving on a circularly polarized antenna. That's the common conclusion of those studies that I referenced. Remember these studies are HF (80-10m), not MF (160m). Second, polarization is not purely random. There is more order to polarization that we generally think due to the ionosphere being immersed in a magnetic field. What's important is where the wave enters and exits the ionosphere - and how well the polarization of the ordinary and extraordinary waves that propagate thru the ionosphere couples to the polarization of your antenna. In my mind that theory translates nicely to the real-world. One of G2HCG's conclusions from his 10m study unwittingly confirmed magneto-ionic theory. I don't think he was even aware of the effect of a magnetic field on a plasma, so that makes his conclusion all the better. Yes, the ionosphere is dynamic and varies over the short-term - so there is some randomness imparted on the what the ionosphere dictates. For the record, G2HCG's conclusion referenced above stated that It was immediately apparent that the number of hops to the ionosphere and back was totally irrelevant. The polarization of signals must therefore be controlled by the last hop. I agree with Herb's comment about implementing a cp antenna on 160m - a very tough job. The big question in my mind would be how do you separate out the difference in vertical patterns when ground is taken into account? Having said all the above, I still say circular polarization on 160m would not be beneficial due to just the ordinary wave being useful. Carl K9LA On Tue, Feb 4, 2014 at 12:03 PM, Tom W8JI w...@w8ji.com wrote: Circular polarization cannot have an advantage on average, or over time. The problem with circular polarization on skywave is the wave has no set rotation, level, or phase. The circular antenna would be fine combining two phase-quadrature fields with a certain lead or lag (depending on rotation or sense), but the arriving signals at HF would be random. They would be just as likely to subtract as to add. Worse, the noise from both systems sums. If you use circular polarization, you are guaranteed a reduction in signal-to-noise the vast majority of time for a small improvement a fraction of the time. This is why microwave links and HF links that have random paths or multiple paths vote with signal-to-noise detectors to pick a single polarization that is optimal at any moment of time. With line-of-sight the signal could have a set, known, repeatable, rotation. With things multi-pathing and bouncing all around, there is no phase or rotation consistency, so they have to vote to the best polarization and ignore the other at any instant. There could also be a system that detects phase and corrects phase to add, but it would have to be a smart system with signal phase correction. In the systems we have, the only practical combining is through stereo diversity. Your brain has to learn to process independent identical phase-locked channels from two different antennas. It does not even have to be polarization differences, spatial differences alone will be enough on HF and MF. For example, two identical Beverage antenna systems here separated maybe 3 wavelengths or more will have entirely different fade times. Signals can be completely out on one, and still workable on the other. Your brain can then learn to sum the independent signals in each ear (if they are phase locked) and make maybe 3-6 dB improvement when both ears have signal, and not be distracted by the left ear noise if only the right ear has signal. Phase coherence is not critical, but lock is. This goes partly away if the channels are not locked. Even 0.1 Hz unlock is deleterious. This ALL goes away if the channels are a few Hz or more out of lock. The advantage goes away if channels are combined, except for seconds or minutes of luck followed by equal times of bad luck. I can sit here and flip switches to parallel channels, either into a receiver or on the output, and these results are repeatable. I can combine dipoles (which by the way are only horizontal broadside to the dipole, tilting to vertical off the ends) and verticals, Beverages and loops, Beverages and Beverages, verticals and Beverages, and it all repeats over and over the same way. I can shift phase between channels bringing wide spaced or cross-polarized systems in matched level and phase, and a few seconds to a few minutes later it is back at 180 out or one channel is adding nothing but noise. I'm afraid just like in commercial systems with scattering or multipath propagation, a circular polarized system is a net detriment. 73 Tom - Original
Re: Topband: circular polarization on 160m
On 2014-02-04 11:02, Herb Schoenbohm wrote: loss of signal results. I would also presume that the construction of a good CP antenna for 160 would be very difficult to perfect. I have seen some antennas for AMSAT work attempting to produce a CP type antenna by have two interlaced yagis, one vertical and the other horizontal, one space 1/4 wave in front of the other, and with a quarter wave delay Herb Schoenbohm, KV4FZ FWIW, I used to know a fellow who got his PhD in antennas working under W8JK at Ohio State University. He worked on a very large HF helix antenna that I believe was circularly polarized. It was basically a cloud warmer pointed straight up. It was suspended from some really large towers. This work was done in the 1950's or 1960's. I don't know what the lower frequency limit of it was. Rick N6RK _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: PZ1AA
Now that the CQWW 160 meter CW contest log submission deadline is past, here is an update from Ramon (PZ5RA) about PZ1AA. --- This morning I got a call from the authorities and they told me they have never submitted this call. So it was a pirate or a fake. --- 73, Don (wd8dsb) _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: circular polarization on 160m
I am pretty new to 160 meters, but just got done with a diversity experiment with FT5ZM last night. My results go along with W8JI’s comments. I heard them on 1.8265 at 2215 UT, and then tried to configure my receiver to utilize space diversity, putting my 90 ft vertical in the left ear, and a long EU beverage in my right ear. Rig was a K3 in diversity mode. I plugged the beverage into the aux receiver jack and selected AUX antenna in diversity mode. The vertical was hooked to the main antenna jack on the K3. I had almost 100% copy between 2220 to 2250 UT when I had to QRT. I wish I had more time to listen! It was wild to hear FT5ZM drifting from ear to ear. It took no effort to accomplish this. I knew I was hearing much better. No fades! It seemed to provide a meaningful improvement to my reception of FT5ZM. Highly recommended! I wish I had tried this before! 73 Dave K1WHS _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Shunt feeding the Skyneedle
You can temporarily use an inductor in series with the cap to extend the range. It will not be a good idea for transmitting, but OK for tuning. - Original Message - From: Carl Braun carl.br...@lairdtech.com To: Tom W8JI w...@w8ji.com Cc: 160 topband@contesting.com Sent: Tuesday, February 04, 2014 10:27 PM Subject: Re: Topband: Shunt feeding the Skyneedle Thanks for the input Tom The only variable cap I have is the EF Johnson which is 60-160pf. I have some ham radio stuff at my parents house not the least is a Jennings 1000pf vac variable rated at 5KV or 7.5kv. I was hoping to use that with a 12v motor for QSYing up the band for contesting. I'll have to ask mom to send it to CA in a pkg with some cookies. When the gamma arm was at 90' I was able to add 160pf to get a resonance point around 1825 but the resistance was still high at 58-60 and X was 20++. Maybe the big vacuum cap would bring that R and X down to where it needs to be. ON4UNs figure 9-85 on page 9-71 of his third edition shows that a tower that is electrical 110 to 130 degrees should have a tap height around 20 meters and a matching cap of 400pf. That being said it may be a good idea to get the vac variable into service. I would assume I would want to raise the gamma arm back up to 90' as it resonated closer to 1825 than the latest iteration which shows a Fr near 1.977 Sent from my iPhone On Feb 4, 2014, at 6:40 PM, Tom W8JI w...@w8ji.com wrote: Here's what changed though...when I had the gamma arm at 90' with the 14 gauge gamma wire 24 away from the tower I was able to insert my Johnson 60-160pf variable cap in series with the gamma wire to get approx 58-60 ohms at X=20. The cap was 2/3 meshed at this point. That's the right way. You have to cancel the reatcance of the drop arm to get a good reading. Maybe you need a larger capacitor to hit the bottom of the band? Resistance normally goes up in a case like yours as frequency is drecreased. NOW that I've lowered the gamma arm to the 67' level...I insert my variable cap and the antenna resonates at 1.970 MHz with R=36 ohms and X=0. For some odd reason the MFJ SWR reading shows 1.0:1 with this 36 ohm reading and, inside the shack, the Ft1000D shows 1.0:1 swr from 1.988 to 1.950 and a 1.5:1 range of 2.007 to 1.930 What does more capacitance do? It now appears that the antenna is a bit short but why am I seeing these crazy high resistance readings with no variable cap in line? You should see them. The MFJ detector is a 50 ohm bridge. It will overflow and give all kinds of goofy readings when impedance is far away from 50 ohms. How can I lower the resonant freq without moving the gamma arm up? Increase the spacing of the gamma wire from the tower? Add more radials? I would have left it at the top and shorted the wire to the tower at different places until I found the sweet spot. But you have to dip the reactance out to really know what you have. I was going to build a three conductor wire cage with the wires spaced 10 apart or so once I had an idea where the antenna resonates. Would a fatter gamma trio drop the resonant freq or just change the capacitance value of the antenna? A fatter shunt wire will lower reactance and resistance. You will need more C, and the tuned resistance will be a bit lower. _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4259 / Virus Database: 3684/7061 - Release Date: 02/04/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: circular polarization on 160m
Hi Carl, This has to be the big picture of the system and the goals, and not a narrow picture of what a wave is doing. I think in the big picture we all agree it is useless. First, when I said advantage, all I meant was there is less fading on HF when receiving on a circularly polarized antenna. That's the common conclusion of those studies that I referenced. Remember these studies are HF (80-10m), not MF (160m). While G2HCG likely had circular polarization on ten meters, there isn't much in the WA3's article that actually convines me he was observing circular polarization. If he did have circular polarization, which he probably did have some, it was only basically straight up. This is entirely different than circular polarization at modest or low angles, which is terribly difficult on any lower band. To be circular polarized at modest to low angles, the horizontal antenna would have to somewhat high above ground and broadside to the DX, and the vertically polarized antenna would have to cross the center line of that antenna, or have some planned offset. In other words, it would have to actually be a circular polarized antenna. EZNEC actually provides a way to look at this. At the bottom of the arrow tabs is Desc Options. Click on that, a choice of fields appear that includes circular. The bottom choice, Linear, Maj, Min, gives a relative comparison of circular to linear. Do a Far Field plot and look in the FF Tab on the left for a level comparison between linear and circular fields. I've seen several enthusiastic studies where a lot of time was spent with an antenna that really could not measure what the experimenter concluded he was measuring. Second, polarization is not purely random. There is more order to polarization that we generally think due to the ionosphere being immersed in a magnetic field. What's important is where the wave enters and exits the ionosphere - and how well the polarization of the ordinary and extraordinary waves that propagate thru the ionosphere couples to the polarization of your antenna. In my mind that theory translates nicely to the real-world. One of G2HCG's conclusions from his 10m study unwittingly confirmed magneto-ionic theory. I don't think he was even aware of the effect of a magnetic field on a plasma, so that makes his conclusion all the better. Yes, the ionosphere is dynamic and varies over the short-term - so there is some randomness imparted on the what the ionosphere dictates. For the record, G2HCG's conclusion referenced above stated that It was immediately apparent that the number of hops to the ionosphere and back was totally irrelevant. The polarization of signals must therefore be controlled by the last hop. The first issue is actually creating a circularly polarized antenna at a useful angle that does not deteriorate signal-to-noise. I think that is a very difficult thing to do unless the target is nearly straight up. Most people think grabbing any horizontal antenna and delaying or advancing phase 90 degrees aganst something vertical produces a circular polarized antenna in any direction at any angle. Nothing is further from the truth. A poorly planned antenna might do that in some directions or at some angles in some directions (with or without the 90 shift), but it will also result in pattern tilt and pattern change. Adding signals and noise unpredictably is not a good thing to do. Even if we somehow manage to improve absolute signal level, we can also easily improve noise level just as much or more. I haven't looked at higher bands, but on 160 through 40 adjusting for some optimum mix largely appears to be either a random thing or useless. On most of HF, at least where I have looked, the same. Having said all the above, I still say circular polarization on 160m would not be beneficial due to just the ordinary wave being useful. The bottom line is we are S/N driven on HF, not absolute signal level. What ratio of V to H signal levels do you expect, Carl? What direction is the rotation? I'm assuming this is actually a circular signal, and not something rotating very slowly that is causing fades? 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Pixel Technologies BevPro-1 Beverage antenna
? I am considering the purchase of a Pixel Technologies BevPro-1 Beverage antenna and wondered if anyone on the list has used one? http://www.pixelsatradio.com/product/the-ultimate-reversible-beverage-antenna-system/ There are a couple of good reviews on eham.net, but I'd welcome some more feedback before making a decision. Many thanks Tracey G5VU _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: circular polarization on 160m
In producing a good satellite AMSAT antenna KLM uses the method of quarter wave stagger of two yagis. One is about a quarter wave ahead of the other and fed with a 1/4 wave delay line. To be circular, one is either staggered 1/4 wave forward and they are fed in phase, or they are even without stagger and fed in quadrature. Polar plots of this antenna suggest that they are not really producing a screw sense CP antenna but rather an Axial mode antenna that receives both vertical and horizontal components of the arriving space signal as they occur. That cannot be done. If two antennas are combined without spatial 90 degree stagger **or** phase 90 degree stagger, they are simply a tilted linear polarization. Many people tilt polarization and think it is both V and H, and think it somehow eliminates polarization rotation fading. All they do is tilt the polarization, and 90 degrees from that tilt is a new null. The confusion is because people and programs express polarization from only tow references, V and H. If I tilted a vertical the right amount it would look like a perfect mix of V and H, but it really would be a single polarization tilted at a 45 degree angle. 90 degrees tilt from that angle, say at -45 degrees, would be a null. With different waves and a left tilt we would have: 1.) circular polarized = no improvement at all 2.) slow lazy fading rotation (this is NOT circular) = no improvement at all 3.) polarization tilted at left 45 = a peak response 4.) polarization tilted an -45 degrees = a deep null. To be circularly polarized the wave has to be rotating fast, at the frequency of the wave, so the wave makes one rotation every wave period. This would NOT be a slow fade anyone would hear, it would just be a few dB signal loss. If the wave were slowly rotating, such as to produce a slow fade, the SENSE of the antennas would not matter one bit. You never get the 3 dB back. You would stop the fade from cross polarization, but would also pick up some significant amount of additional noise. I'm not sure how well thought-out or properly conveyed any of this has been, so I'm enjoying the brain exercise. A circularly polarized antenna on 1 MHz cycles through the entire polarization shift in 1uS. A circularly polarized antenna on 1 MHz cycles through one electrical rotation in 1 uS. Anyone here having fading at a 0.5464481 uS rate? If so, the CP antenna will either make fading near infinite or near zero. :) The way I see it is if the rate is not 0.546 uS or so, you do not have circular polarization.You have a slowly rotating wave, and the sense of the RX antenna would be meaningless unless you could time-sync rotation at that slow fading rate. Someone correct me if I am wrong. 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: FT5ZM in Log!!
Hello All, The just updated logs from FT5ZM shows my 160 Meter QSO on 02/03/14 at 0010Z!! If your QSO was missing recheck the on line log!! 73, Ted K2QMF How to Stay Asleep Researchers have discovered a revolutionary secret to stay asleep http://thirdpartyoffers.juno.com/TGL3141/52f285b63cb6b5b64f7est02vuc _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: circular polarization on 160m
Tom ' The way I see it is if the rate is not 0.546 uS or so, you do not have circular polarization.You have a slowly rotating wave, and the sense of the RX antenna would be meaningless unless you could time-sync rotation at that slow fading rate. Someone correct me if I am wrong. 100% correct My system has two WF's, same gain, one vertical and another horizontal, feeding two preamps into IC7800 two receivers. When there is fading on the signal E-W, the time of the rotation from H to V could be long as 5 minutes, most of the time between 1 to 2 minutes. Using M=S on the IC7800 I can keep the two receivers at same frequency, and I can hear one receiver on each ear. I used to QSO Raoul ZS1REC during summer time and sometimes we start the QSO using V pol and finished on H pol.. About the signal noise gain using H and V with two identical receivers, I can say there is no gain at all, when the signal is weak, I switch the other antenna off and hear with only one channel. The advantage to have both is just to avoid listening in the wrong antenna listening on both antennas at the same time. It is not diversity eider because my antennas are only 60 ft. apart . Besides E-W when the signal is coming from less 45 degree and it is fading, I never see rotation, the vertical signal can have a deep QSB and the horizontal signal constant with no QSB. That just happened last Saturday with the FT5ZM, the horizontal signal was solid all the time with no variation on the intensity, however the vertical signal had deep and fast QSB. My take on that is the propagation mode or multi-path, signals can arrive from a refraction out of a duct and or from the same direction but from a different region on the ionosphere. There is no real correlation between the two polarizations signals, in practice they don't mix. It is very different from HF or VHF where the wave is always coming from the same media. Another point is that refraction increase with the decrease square of the in frequency, on 160m the refraction is stronger than 80 or up, as a result it is not necessary to transmit a horizontal signal to answer a horizontal polarized income signal. When the TX signal reach the first refraction point the wave split in two one vertical and another horizontal. What means is the efficiency to couple the TX signal with the atmosphere this is more important than the polarization itself, but 160m only, moving up in frequency the results are completely different, and 30 MHz to 50 MHz it is even special because it is transition from HF to VHF propagation mode. The experiments on 28 MHz does not apply to 1.8 MHz. Between 1 and 2 MHz , everything is different from HF or VHF Regards JC N4IS _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Pixel Technologies BevPro-1 Beverage antenna
I would sure like to know the evaluation of the team at FT5ZM of this coaxial cable antenna by Pixel. At first there were reports of not hearing good on the low bands. Several posted remarks that different RX antennas were being constructed for better reception on the low bands. I would like to know what works and what doesn't before I buy it and FT5ZM would be a good test drive. Herb Schoenbohm, KV4FZ On 2/5/2014 1:00 PM, Tracey Gardner wrote: ? I am considering the purchase of a Pixel Technologies BevPro-1 Beverage antenna and wondered if anyone on the list has used one? http://www.pixelsatradio.com/product/the-ultimate-reversible-beverage-antenna-system/ There are a couple of good reviews on eham.net, but I'd welcome some more feedback before making a decision. Many thanks Tracey G5VU _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Pixel Technologies BevPro-1 Beverage antenna
I would sure like to know the evaluation of the team at FT5ZM of this coaxial cable antenna by Pixel. At first there were reports of not hearing good on the low bands. Several posted remarks that different RX antennas were being constructed for better reception on the low bands. I would like to know what works and what doesn't before I buy it and FT5ZM would be a good test drive. Herb Schoenbohm, KV4FZ On 2/5/2014 1:00 PM, Tracey Gardner wrote: ? I am considering the purchase of a Pixel Technologies BevPro-1 Beverage antenna and wondered if anyone on the list has used one? http://www.pixelsatradio.com/product/the-ultimate-reversible-beverage-antenna-system/ There are a couple of good reviews on eham.net, but I'd welcome some more feedback before making a decision. Many thanks Tracey G5VU _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Pixel Technologies BevPro-1 Beverage antenna
I purchased 1 set, it arrived yesterday. I already have 2 (coax) 800 Ft beverages installed and will try the unit on the NE beverage first. Butwe have about 15 inches of snow and more coming so I don't think it will be installed until next week. I will report as soon I have the results. 73 Will K6ND -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Herb Schoenbohm Sent: Wednesday, February 05, 2014 2:40 PM To: TopBand List; Tree Subject: Re: Topband: Pixel Technologies BevPro-1 Beverage antenna I would sure like to know the evaluation of the team at FT5ZM of this coaxial cable antenna by Pixel. At first there were reports of not hearing good on the low bands. Several posted remarks that different RX antennas were being constructed for better reception on the low bands. I would like to know what works and what doesn't before I buy it and FT5ZM would be a good test drive. Herb Schoenbohm, KV4FZ On 2/5/2014 1:00 PM, Tracey Gardner wrote: ? I am considering the purchase of a Pixel Technologies BevPro-1 Beverage antenna and wondered if anyone on the list has used one? http://www.pixelsatradio.com/product/the-ultimate-reversible-beverage- antenna-system/ There are a couple of good reviews on eham.net, but I'd welcome some more feedback before making a decision. Many thanks Tracey G5VU _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: circular polarization on 160m
The way I see it is if the rate is not 0.546 uS or so, you do not have circular polarization.You have a slowly rotating wave, and the sense of the RX antenna would be meaningless unless you could time-sync rotation at that slow fading rate. Someone correct me if I am wrong. 100% correct I hope Carl K9LA has input, but I cannot think of a single way that a circular polarization signal would have fading that would be corrected by changing from a linear polarized antenna to a circular system. This is what perplexes me about any advantage of using a circular RX antenna based on the signal: 1.) If the wave was circularly polarized, that could not cause a fade on a linearly polarized antenna. It rotates far too fast for that. It would just be a steady 3 dB loss. 2.) A slowly rotating signal can go into fades as the electric field crosses the minimum response of an antenna. Making an antenna that responds **in a correct way**, so we don't have a skewed or sloped linear polarization (because that would still fade), might cure that fade. The cure would always be at a S/N penalty for half of the rotation or more. The tradeoff would be a few moments large advantage (during the fade) for a longer time disadvantage. If the horizontal antenna did not have comparable directivity to the vertical, that system could totally hose S/N for all but a very short time, that time being when there would have been no signal. 3.) On VHF, and even ten meters, we can build a directive vertical and horizontal antenna with a good pattern at low wave angles. The wavelength is short enough we can get away from noise, the earth, and have low angle horizontal patterns. But.a linearly polarized antenna would not fade to zero from a rotating wave unless it was rotating slow. The period of rotation for a circularly polarized wave is far too fast for that. I can tune into FM BC circularly polarized signals with linear polarized antenna, either a dipole or vertical, and not have a bit of fading. Any fading would only come from my having the wrong rotation on a circular receiving antenna, or a long term null of response from a very slow rotation. This is what perplexes me...to have fading from polarization it has to rotate slow. That is not a circularly polarized wave by the normal use of the term. If the wave rotates slow, the R-H L-H sense of the antenna makes no difference at all. So why are experimenters hearing slow fade on a linear antenna, and correcting that fade ONLY with a certain L-H or R-H antenna? It was rotating fast enough to be circular, the antenna rotational sense would make zero difference and it would not be fading on a regular single polarization antenna. The wave rotation would, at best, only cause a 3 dB fade into a linearly polarized antenna. This gives me pause about what people are measuring and writing. If they are correct, hundreds of FM BC transmitters need to change their antennas. We have a WA3 claiming the rotational direction makes a difference, that implies the wave is circular. But if the wave were circular, he would not have fading on a linear antenna. 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: circular polarization on 160m
Tom, Perhaps it is much simpler than that. Recalling KL7AJ's article, http://www.nxtbook.com/nxtbooks/arrl/qst_201203/index.php#/42 he states that the magnetic field of the earth splits every HF signal into a right hand or left hand circular wave. Add to that the unevenness of the ionosphere can tilt the wave as well. All this is something that seems that it could cause slow fading. An interesting question, to be sure. Jim - KR9U -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Tom W8JI I hope Carl K9LA has input, but I cannot think of a single way that a circular polarization signal would have fading that would be corrected by changing from a linear polarized antenna to a circular system. This is what perplexes me about any advantage of using a circular RX antenna based on the signal: 1.) If the wave was circularly polarized, that could not cause a fade on a linearly polarized antenna. It rotates far too fast for that. It would just be a steady 3 dB loss. 2.) A slowly rotating signal can go into fades as the electric field crosses the minimum response of an antenna. Making an antenna that responds **in a correct way**, so we don't have a skewed or sloped linear polarization (because that would still fade), might cure that fade. The cure would always be at a S/N penalty for half of the rotation or more. The tradeoff would be a few moments large advantage (during the fade) for a longer time disadvantage. If the horizontal antenna did not have comparable directivity to the vertical, that system could totally hose S/N for all but a very short time, that time being when there would have been no signal. 3.) On VHF, and even ten meters, we can build a directive vertical and horizontal antenna with a good pattern at low wave angles. The wavelength is short enough we can get away from noise, the earth, and have low angle horizontal patterns. But.a linearly polarized antenna would not fade to zero from a rotating wave unless it was rotating slow. The period of rotation for a circularly polarized wave is far too fast for that. I can tune into FM BC circularly polarized signals with linear polarized antenna, either a dipole or vertical, and not have a bit of fading. Any fading would only come from my having the wrong rotation on a circular receiving antenna, or a long term null of response from a very slow rotation. This is what perplexes me...to have fading from polarization it has to rotate slow. That is not a circularly polarized wave by the normal use of the term. If the wave rotates slow, the R-H L-H sense of the antenna makes no difference at all. So why are experimenters hearing slow fade on a linear antenna, and correcting that fade ONLY with a certain L-H or R-H antenna? It was rotating fast enough to be circular, the antenna rotational sense would make zero difference and it would not be fading on a regular single polarization antenna. The wave rotation would, at best, only cause a 3 dB fade into a linearly polarized antenna. This gives me pause about what people are measuring and writing. If they are correct, hundreds of FM BC transmitters need to change their antennas. We have a WA3 claiming the rotational direction makes a difference, that implies the wave is circular. But if the wave were circular, he would not have fading on a linear antenna. 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: circular polarization on 160m
James You brought a good article about HF propagation, however the behavor on 160m is different from HF. If you check on the KL7A arcticle figure 1 what is happening between 1 and 2 MHz you can see that the green and red does not behaivor the same way as above 2 MHz. This subject is more complex because there us no shirt answer, actualy between 1 and 2 MHz. the ionosphere does not support linear polariration wave. The wave are actualy eliptical and not circular for most directions. You can check the long answer on the must read book from NM7M . R Brown 'The Big Gun's Guied to Low Band Propagation . Magneto-iomic Theory pag 47 to 56 ; and Power coupling pag 57. Thanks to Karl. K9LA, the book is available on his also must read site on the 160m link http://k9la.us/html/160m.html Regards JC N4IS _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: circular polarization on 160m
Jose, I am only presenting the possibility that if the ionosphere (where 160 propagation happens) isn't uniformly smooth and instead consists of warps, wrinkles and tilts that in a *dynamic ionosphere*, this could be at least one reason we are experiencing slow fades. Elliptical polarization, assuming that it is ever changing, could provide yet another degree of selective fading. I'm don't think I *totally* understand why KL7AJ says that at HF the ionosphere forbids the propagation of linearly polarized signals. If at the magnetic equator, and signals were East to West to equal the earth magnetic tilt of the signals, it seems that at an instance in time that a linear polarized signal could happen.But that may be nit picking. Jim - KR9U From: JC N4IS [mailto:n...@comcast.net] Sent: Wednesday, February 05, 2014 10:45 PM To: jbw...@comcast.net; 'Tom W8JI'; he...@vitelcom.net; topband@contesting.com Subject: RE: Topband: circular polarization on 160m James You brought a good article about HF propagation, however the behavor on 160m is different from HF. If you check on the KL7A arcticle figure 1 what is happening between 1 and 2 MHz you can see that the green and red does not behaivor the same way as above 2 MHz. This subject is more complex because there us no shirt answer, actualy between 1 and 2 MHz. the ionosphere does not support linear polariration wave. The wave are actualy eliptical and not circular for most directions. You can check the long answer on the must read book from NM7M . R Brown 'The Big Gun's Guied to Low Band Propagation . Magneto-iomic Theory pag 47 to 56 ; and Power coupling pag 57. Thanks to Karl. K9LA, the book is available on his also must read site on the 160m link http://k9la.us/html/160m.html Regards JC N4IS _ Topband Reflector Archives - http://www.contesting.com/_topband
