Hi guys Polarization does play a lot on 160m for two reasons. I can say that because I am using my HWF (two horizontal flags end fire) since 2009. The first one is local man made noise that propagate only vertical due the attenuation on the horizontal component near the ground. And Second the DX signal always come in both polarization. The result form the two reasons is an optimized signal to noise ration using horizontal polarization.
I have both WF with the same RDF, during SR or SS there is almost no sky noise coming from the back because of the darkness, however local man made noise comes from any direction, especially if you live in a city lot like I do. Most of the time the noise is coming at the same direction you want to hear the DX, and if you add power line noise the situation deteriorates a lot for the VWF due vertical polarization. Using my HWF I normally get 10 dB better SNR than my VWF that has the same RDF and same aperture of 74 degree measures, I can turn the antenna and measure it, they are not optimized for best F/B, I optimized them for maximum rejection of local man made noise. The HWF is not a dipole. The two phased loops take of angle us 40 degree and there is a huge attenuation for signals above 60 degree. Low dipole is a huge issue if the dipole is resonant, it will interact with all other receiver antennas and will destroy directivity of all of them, if you want to use a low dipole make it not resonant. Gain in not important so it can be short as a 30 m dipole and still will hear the same way. Another issue with low dipoles is the amount of energy absorbed from the TX antenna. If you connect a power meter and a 50 ohms load o the low dipole and transmit KW on the TX antenna, you can measure several WATTS at the low dipole . You can burn you front end with a low resonant dipole. Adding to all that there is another very interesting observation from my last 5 year using a high RDF horizontal RX antenna, when the TX signal refract on the ionosphere the signal split in two waves, that was very well explained by K9LA. What I observed is that these two waves does propagate in different directions. I normally receive VK6 near my SR with better SNR horizontal from 210 degree SSW and with better SNR from 280 degree vertical. Sometimes the horizontal peak is 20 minutes before the vertical peak that is most of the time at my SR. 73's N4IS JC -----Original Message----- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of John Kaufmann Sent: Wednesday, December 17, 2014 8:59 PM To: topband@contesting.com Subject: Re: Topband: 8 circle: DXE vs Hi-Z Good points about polarization. If the signals and/or noise are polarized predominantly in one state, then RDF may not be a good predictor of SNR performance, particularly if the antenna receives predominantly in an orthogonal polarization. On the other hand, if the polarization state of the signals and noise evolve randomly with no preference for any one state, which is often assumed for skywave signals, then RDF will be--on average--a good receiving metric, subject to the previous stated qualifications about the spatial distribution of the received noise. However, some of the past discussions on this reflector about preferential polarization of skywave signals on 160 may call into question the assumption of randomly polarized signals. 73, John W1FV -----Original Message----- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Richard (Rick) Karlquist Sent: Wednesday, December 17, 2014 3:19 PM To: Lee K7TJR; 'Terry Posey'; 'John Kaufmann'; topband@contesting.com Subject: Re: Topband: 8 circle: DXE vs Hi-Z All this discussion about RDF overlooks the issue of polarization. If you make an array of verticals with a certain RDF (assuming noise comes from all directions uniformly), the array will be better than an individual vertical by the RDF factor. However, what I have found is that a horizontally polarized antenna, such as a low dipole frequently receives considerably better than a vertical. In that case, you would be better off using an array of low dipoles. The reason why horizontal polarization can be better is that the horizontal component of terrestrial based noise is highly attenuated over distance as a ground wave. Rick N6RK _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband
