Hi Rick >> I had full size 160M dipoles (not inverted vees) up at 9 meters and 18 meters for about six months and did a lot of A/B'ing of them. On receive, there was never any difference in audible S/N ratio. >>
This result is 100% sure to happen. Any time you have more than one resonant antenna, they will couple with each other. A-B test on 160m is very difficult to be done properly when one antenna is resonant. There is several ways to feed a resonant antenna, one of them is driving with another resonant antenna, like a 2 elements yagi, any element close to 1/2 waive reradiate the energy it receives from the other element. The situation with small receiver antennas is worst, If you want to compare a RX antenna like EWE, Flag or small vertical array with a low dipole, the interaction will be so intense that all antennas will receive the same signal noise. The dipole must be at 300 to 500 Ft far from the RX antennas to reduce the interaction. To eliminate the interaction 1000Ft is necessary. It is just electro magnetism law. Elevated radials does the same with RX antennas. Does not matter if you are receiving or transmitting the integration works at the same way, that's the way any yagi works on RX and TX with the same gain. RDF is the key point to improve signal noise, not gain. Vertical or low dipole has very or none directivity, so low RDF or directivity does not improve signal noise. Unfortunately, physically detuning any resonant antenna is a must for a good reception on 160m using external RX antennas, You cannot see but it is there. Detuning or neutralizing a resonant antenna means change the dimension to avoid the resonance, it has nothing to do with the feed impedance of the antenna or structure. Shorting the end of the coax cable is just not enough to detune the antenna, only makes it a little longer or shorter. Regards Jose Carlos N4IS _______________________________________________ Topband reflector - [email protected]
