Re: Topband: Flag/Pennant Question
My small city lot doesn't offer the luxury of room for large, let alone multiple low band receive antennas. In fact, the lot is so small that ground mounted antennas like the K9AY are impossible. The only real estate available is up on the roof. The reduction in noise when comparing the flag to a shunt fed tower (vertical) is nothing short of dramatic. 73 - Steve WB6RSE > On Dec 1, 2011, at 10:48 AM, W2PM wrote: > > Agreed fully. But the very low output antennas usually go hand in hand with > small suburban or non rural environs and thus very noisy. To achieve a > useful sn ratio with all the noise and low output is a big challenge > especially if you are not in the lower latitudes. I note n4is comments from > noisy FL lot BUT there is a huge diff in propagation and sig levels from > there to NY area. U keep believing more and more that an additional factor > for good rx conditions is also wide open terrain and not only because those > are typically quiet. During a recent area wide power blackout here for 5 days > it was very quiet but still could t hear many things others less than 100 > miles were hearing in far more open land. I think it's because arrival > angles are so low obstructions will degrade levels. > > I have no issues on 80 and higher. Hear what everyone else does but 160 is a > major major challenge on rx. > > Sent from my iPhone > > On Nov 30, 2011, at 5:08 PM, wb6r...@mac.com wrote: > >> I've used a variety of loops, from a small rotatable coax diamond to my >> present receiving antenna, a large 14 x 29 ft flag. >> It is more useful to think of these antennas as providing directivity, not >> gain. What's important is a relative improvement in signal to noise ratio. >> It is not unusual to have improved copy on the desired signal while the loop >> is pointed at other than a dead on heading. >> >> 73 - Steve WB6RSE >> > ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Flag/Pennant Question
Agreed fully. But the very low output antennas usually go hand in hand with small suburban or non rural environs and thus very noisy. To achieve a useful sn ratio with all the noise and low output is a big challenge especially if you are not in the lower latitudes. I note n4is comments from noisy FL lot BUT there is a huge diff in propagation and sig levels from there to NY area. U keep believing more and more that an additional factor for good rx conditions is also wide open terrain and not only because those are typically quiet. During a recent area wide power blackout here for 5 days it was very quiet but still could t hear many things others less than 100 miles were hearing in far more open land. I think it's because arrival angles are so low obstructions will degrade levels. I have no issues on 80 and higher. Hear what everyone else does but 160 is a major major challenge on rx. Sent from my iPhone On Nov 30, 2011, at 5:08 PM, wb6r...@mac.com wrote: > I've used a variety of loops, from a small rotatable coax diamond to my > present receiving antenna, a large 14 x 29 ft flag. > It is more useful to think of these antennas as providing directivity, not > gain. What's important is a relative improvement in signal to noise ratio. It > is not unusual to have improved copy on the desired signal while the loop is > pointed at other than a dead on heading. > > 73 - Steve WB6RSE > ___ > UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Flag/Pennant Question
I've used a variety of loops, from a small rotatable coax diamond to my present receiving antenna, a large 14 x 29 ft flag. It is more useful to think of these antennas as providing directivity, not gain. What's important is a relative improvement in signal to noise ratio. It is not unusual to have improved copy on the desired signal while the loop is pointed at other than a dead on heading. 73 - Steve WB6RSE ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Flag/Pennant Question
You wrote They have perfect cardiod patterns just like the full sized models BUT negative 45 db "gain" is fairly useless for DX" Working with antennas with low gain is a huge challenger however 100% possible. I worked 249 counties on 160m ad 39 zones in the last 5 years living in a suburban area west of Fort Lauderdale. My RX antennas gains are -43 db for the VWF and -48db for the HWF. My noise floor varies from -96 dBm to -85 dBm, very noisy when you compare to rural areas that can be low as -120 dBm of noise on 160m. Interaction with any resonant TX or RX antenna must be reduced detuning it during RX. If you are not willing to detune your TX antenna don't even try to work with low gain RX antennas, it will be a waste of time. Common mode noise management and very good shield is a must to reduce man made noise. Also low NF preamps are necessary to keep a good signal noise near the receiver noise floor. George AA7JV is working with small loops with a new concept with some consistent results. The issue with small loaded loops is the thermal noise of the loop limiting the possibility to amplifier signals bellow the thermal noise of the loop. Dr Dallas idea with multiple turn's loops was to raise the gain and reduce the thermal noise but the additional inductance spoiled the cardioid patter on 160m, it seem to work on LF. Regards Joe Carlos N4IS ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Flag/Pennant Question
-- Pete W2PM wrote : Im starting to compare a half size pennant now pointing to VK from here with a Short bog. Something less than 150 ft. long. So far casual observations areshowing significantly greater output from the bog but I need to do more careful and controlled observations. The half pennant is too low in output for the veryweak signals I am experiencing here. I've used the half quite well to Europefor 160 however. --- This summer I installed 3 small point fed pennants (51.6% the size of full size pennants) pointing 40 deg (Europe), 160 deg(Caribbean), and 300 deg (Pacific\Asia) from the Indianapolis area, and I am using a W1FB preamp which has more than enough gain to match S meter readings equivalent with my 68 foot base loaded vertical on 160 meters (looks like my preamp still has approximately 12 db of additional gain if needed). If interested you can hear some of my recordings using my pennants on YouTube (just do a search for WD8DSB which will bring up a listing of numerous recordings I have done). I also have a simple website that documents my 3 point fed pennant project and the URL is http://sites.google.com/site/pennantflagantennas/ I did some slight modifications to the W1FB preamp to prevent failures of the amplifier IC when the amplifier was exposed to high signal levels from my TX antenna when I was running 100 watts, and I documented this modification last year on the topband reflector. The modification has worked just great, and my TX antenna is only 40 feet from the feedpoint of my point fed pennants (running 100 watts I have not found the need to use any additional front end protection devices besides the modifications I incorporated in my preamp). At some point in time I would like to try a couple of very low noise preamps in series (two in series due to the gain requirement) to see if a lower noise factor preamp offers any advantage on 160 meters compared with the W1FB preamp (I previously tried a KD9SV preamp vs the W1FB preamp using a small loop on 160 meters and did not notice any improvement in S\N ratio). Next season I will probably try phased half size pennants in an attempt to approach the performance of a full size beverage (similar RDF values) from a small suburban lot, but will also probably test out a BOG. 73's Don Kirk (wd8dsb) ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Flag/Pennant Question
If you want that you can look at the Waller versions which stack two antennas. N4IS is the guru. But everyone is describing a very small version of the terminated loops here. 2 by 2 meters is crazy small. I have experimented a great deal with these small loops when K6SE came up with the concept. They have perfect cardiod patterns just like the full sized models BUT negative 45 db "gain" is fairly useless for DX. It's fine for BCB or more local work but the bare minimum for any DX performance would be a half sized pennant. That's 15 ft by 7. I'd only use that if you are in a very quiet area too as the output is quite low and a preamp would pull in too much local noise if you have it. A tiny loop like the 2 meter squAre is better than a magnetic loop of the same size though. Unless you have a strong point source of noise you need to null which is where the mag loop would work out. There is no sense at all in trying to deepen the rear null. 35db null depth plus is pretty significant in any size. Im starting to compare a half size pennant now pointing to VK from here with a Short bog. Something less than 150 ft. long. So far casual observations are showing significantly greater output from the bog but I need to do more careful and controlled observations. The half pennant is too low in output for the very weak signals I am experiencing here. I've used the half quite well to Europe for 160 however. Sent from my iPad On Nov 29, 2011, at 21:25, Arthur Delibert wrote: > > I was wondering whether it might produce a narrower pattern in the front, or > a deeper null off the back, or maybe even both. But indications from two > people who have either modeled it or built it are that it requires 3 load > resistors, one in each leg, and produces a highly reactive antenna with only > a slight increase in gain. > > Clearly better and simpler to add a second antenna and connect them through a > phasing device to null the unwanted stations, as described by Mark Connelly, > WA1ION. > > >> From: w...@aol.com >> Date: Mon, 28 Nov 2011 21:49:40 -0500 >> To: radio7...@msn.com >> CC: topband@contesting.com >> Subject: Re: Topband: Flag/Pennant Question >> >> Why would you do that? >> >> Sent from my iPhone >> >> On Nov 27, 2011, at 8:59 PM, Arthur Delibert wrote: >> >>> >>> I'm wondering if anyone has ever built or modeled a multi-turn flag or >>> pennant antenna. I'm thinking maybe an odd number of turns with the >>> resistor in the middle of the middle turn. >>> >>> Thanks. >>> >>> --Art Delibert, KB3FJO >>> ___ >>> 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: Flag/Pennant Question
I was wondering whether it might produce a narrower pattern in the front, or a deeper null off the back, or maybe even both. But indications from two people who have either modeled it or built it are that it requires 3 load resistors, one in each leg, and produces a highly reactive antenna with only a slight increase in gain. Clearly better and simpler to add a second antenna and connect them through a phasing device to null the unwanted stations, as described by Mark Connelly, WA1ION. > From: w...@aol.com > Date: Mon, 28 Nov 2011 21:49:40 -0500 > To: radio7...@msn.com > CC: topband@contesting.com > Subject: Re: Topband: Flag/Pennant Question > > Why would you do that? > > Sent from my iPhone > > On Nov 27, 2011, at 8:59 PM, Arthur Delibert wrote: > > > > > I'm wondering if anyone has ever built or modeled a multi-turn flag or > > pennant antenna. I'm thinking maybe an odd number of turns with the > > resistor in the middle of the middle turn. > > > > Thanks. > > > > --Art Delibert, KB3FJO > > ___ > > 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: Flag/Pennant Question
On Mon, 28 Nov 2011 21:49:40 -0500 W2PM wrote: > Why would you do that? > > >> I'm wondering if anyone has ever built or modeled a >>multi-turn flag or pennant antenna. I'm thinking maybe an >>odd number of turns with the resistor in the middle of >>the middle turn. >> --Art Delibert, KB3FJO Art, I have tried it (what the heck, why not?). Using a 2m x 2m loop, 1m above average ground: The F/B (better than 25 dB) and RDF (7.8 dB) are the same as a single turn loop. Gain is higher by 2 dB (-46 dBi). Needs three separate loads, one on each of the back-side vertical wires. This antenna would be hard to match due to high and highly reactive feed point impedance. I believe it is not worth the trouble for the small increase in gain. Cheers, George, AA7JV ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Flag/Pennant Question
Why would you do that? Sent from my iPhone On Nov 27, 2011, at 8:59 PM, Arthur Delibert wrote: > > I'm wondering if anyone has ever built or modeled a multi-turn flag or > pennant antenna. I'm thinking maybe an odd number of turns with the resistor > in the middle of the middle turn. > > Thanks. > > --Art Delibert, KB3FJO > ___ > UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: Flag/Pennant Question
I'm wondering if anyone has ever built or modeled a multi-turn flag or pennant antenna. I'm thinking maybe an odd number of turns with the resistor in the middle of the middle turn. Thanks. --Art Delibert, KB3FJO ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
