Hi Carl and top-band lovers I would like to mention Chapter 7.6 as well, polarization matching, and also 7.7 Fading. I started developing my HWF early 2009 and I think there is no more to squeeze from it.
Here some update in respect of polarization on 160m. It is a game!, vertical and horizontal field changes all the time, an elliptic can describe better the waves on 160m. My last HWF tuning gave me another 6-8 db improvement on the signal noise ratio. The HWF is really an "all directions noise cancelling antenna ( Va-Vb=0)", the goal is maximum attenuation on the vertical field an good directivity on the horizontal field. The takeoff angle is always the same and does not change with the height above ground ,it always very close to 40 degree. It is alike high horizontal dipole that takeoff change with the height from ground. The HWF has a deep null from high angle signals at any height above ground. The game is maximum attention on the vertical signal because most of the manmade noise, power line noise, city noise propagate with vertical polarization due the proximity with the ground for 160m waves. For 160m the HWF needs to be over 100 ft. to perform well on the horizontal signals, 50 ft. is ok for 80m and up. The HWF works 160m to 30m with excellent performance depending on the area of the loops. The HWF gain is around -43 db, and the vertical attenuation can be adjusted to deep another -50db, the total attenuation front and back is > -90 db , It has a front null and a back null for vertical signals. This is a weak, weak, weak signal system implementation, very complex by nature by receiving near the receiver noise floor most of the time. Depending on the direction of the wave the H/V ratio can be -20 db or more both ways, most of the time the vertical component is 10 to 20 db stronger than the horizontal component. When you combine the 4 variables, vertical gain, horizontal gain, vertical noise QRM and the signal H/V ratio you have your final signal to noise ratio, however on top of that you need to add the propagation noise as well. Another dependence is the solar cycle. We are at the peak of the solar cycle and the propagation this year has been very different . Long pass is peaking at the SS or SR and the signals from North are showing a strong horizontal component. or it could be just coincidence, just time will tell. Nowadays I can copy better weak signals with my HWV than my VWF in all directions. I just observed that recently with 8Q7BM, NH0Z,V63DX,4J6RO, 4K6FO and 4L5O, signals from NNW and NNE better on HWF. It is the first time I can hear better signals coming North with the HWF. It is all about signal noise ratio. For long path the new adjust also helped a lot. I detuned the TX tower to minimum noise on the HWF, making the diagram symmetrical on the polar plot. It looks like a butterfly for local vertical signals. Peter HS0ZKX is coming strong from SSW every 28 days. Just after the solstice last month the long path propagation was just fantastic. WV8. H40,RA0. JA. BA. BG and DU7 copy with Q5 from SSW from Dec 25th to Jan 1st , but few QSO's. only JA and DU7 on the log. FT5ZM only on the HWF as well. I agree with Carl. There hasn't been much work in polarization field on 160m, however It is a fascinate subject. Come on in folks! Regards JCarlos N4IS -----Original Message----- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Carl Luetzelschwab Sent: Monday, February 03, 2014 12:17 PM To: topband@contesting.com Subject: Topband: circular polarization on 160m I hope everyone has had a chance to work FT5ZM on topband. With respect to circular polarization on our HF bands (3.5 - 28 MHz) and on 6m, theory says both the ordinary and extraordinary waves propagate thru the ionosphere with pretty much equal ionospheric absorption. Thus circularly polarized antennas can provide an advantage. Some of the real-world examples I'm aware of have been documented by G2HCG on 10m (in the old Communications Quarterly), by the original K6CT on 20m (in the RSGB Bulletin) and by WA3WDR on 75m (a web paper). I'm sure there are others out there, too. On 160m, theory says the extraordinary wave incurs much more ionospheric absorption (more heavily attenuated) due to 1.8 MHz being so close to the electron-gyro frequency. Thus in theory only the ordinary wave is useful on 160m, which says circular polarization wouldn't do any good. Now things happen on 160m in the real-world that we simply don't understand. For example, an ordinary wave can excite an extraordinary wave under certain ionospheric conditions (if you'd like to read more, curl up in a warm place on a cold night with Chapter 3 in Ionospheric Radio by Kenneth Davies). Could this be happening? I don't think we can rule it out. In my opinion based on all the reports on this reflector over the years, it seems to me that having selectable elevation angles is more important than polarization. But I also admit that there hasn't been much work in the polarization field (no pun intended) on 160m (except for N4IS with his horizontal Waller flag - which makes sense with theory for roughly East-West propagation close to the geomagnetic equator). Carl K9LA _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband