Have to remember that W8JI, ON4UN and many others were not lying or deceived. What we are finding out is that a major rule has some exceptions. If you're talking to a club member in the US, you better point them to verticals, T's or inverted L's.
One of the missing aspects of dipole vs. vertical comparisons is the major risk of a poor lossy counterpoise for the vertical. People have lost quite a bit more than 1/2 their power in bad radial implementations, or in various loss issues not affecting a dipole. One of the contributions of an inverted L is filling out the high "hole" in a vertical ot "T" radiation pattern. That could account for a lot of differences. Knowing absolutely the incoming angle on DX is still something without a lot of measured documentation around. Never can have enough antennas. 73, and may you work whatever you hear, Guy K2AV On Mon, Nov 26, 2018 at 4:20 PM Mike Waters <[email protected]> wrote: > This has been an eye-opening discussion for me! I have always preached the > 'gospel' of vertical-is-usually-best based on W8JI, ON4UN, and *many* other > long-time Topbanders. Someday I'll have to revise > www.w0btu.com/160_meters.html and include a link to this thread. > > I stand corrected. Thank you, gentlemen! :-) > > 73, Mike > www.w0btu.com > > On Mon, Nov 26, 2018, 12:56 AM Steve Ireland <[email protected]> wrote: > > > Hi Frank (and Rick) > > > > Somewhere I have a map of the lines of geomagnetic latitude superimposed > > on a Mercator projection of the world, but I can’t find it right now. > > Unlike the ruler-straight lines of conventional latitude, geomagnetic > > latitude lines wander across the world like a collection of snake tracks. > > > > As a result of how geomagnetic latitude snakes across the globe, a > > comparison can’t be directly made between similar geomagnetic latitudes > in > > the northern and southern hemispheres – where Tom W8JI lives is probably > > very different to me in terms of the closeness of his geomagnetic > latitude > > to the electron gyro-frequency. As Carl K9LA points out, the geomagnetic > > latitude relates to polarization and involves the ordinary and > > extraordinary waves that propagate through the ionosphere, and how 160m > is > > affected by being close to the electron gyro-frequency. > > > > About 10 to 15 years ago, Carl, Nick Hall-Patch VE7DXR and Bob NM7M (SK) > > (also a physicist like Carl, as I’m sure you recall) helped Mike VK6HD > (SK) > > and I to understand why our horizontal cloud-warmers outperformed > efficient > > vertical antenna systems in SW WA. > > > > You are quite correct, the Fresnel zone where I live (the mostly far > field > > region where ground gain is developed) has very poor conductivity. And, > to > > repeat your point as this is not as widely known as it should be, poor > > Fresnel Zone conductivity has very little impact on the performance of > > horizontally polarized antennas, while having a major impact on > vertically > > polarised ones. > > > > While the Fresnel (far field) zone of my location, is basically rock > > (granite and ‘coffee rock’), Mike’s final location beside the Kalgan > > estuary appeared to have much better Fresnel zone conductivity, with less > > rock than me and, in around half the compass directions, salt water. > > However, his inverted-L with an 80’ vertical section over 120 buried > > quarter-wave radials at Kalgan performed only marginally better than our > > previous attempts at vertical antenna systems did. > > > > On this basis, I came to the conclusion that the dominant problem was > > likely to be the geomagnetic latitude issue, rather than poor > conductivity > > in the Fresnel zone – which it certainly is also an issue here. > > > > To investigate this further, I sought out the opportunity to operate > > directly by the sea here with a good vertical antenna. After much > > paperwork, I managed to get permission to operation from the Cape Leeuwin > > lighthouse, which is 40m-plus high and on a narrow finger of land > > surrounded by sea for over 300 degrees. > > > > In a Stew Perry TBDC in the early 2000s, with the assistance of my friend > > Phil VK6PH, we put up a full-sized quarter-wave wire vertical on the most > > seaward side of the lighthouse, less than 60 metres from the sea. This > was > > fed against a quarter wave counterpoise and the feeder decoupled with a > > large ferrite choke to stop common mode effects. On the other side of > the > > lighthouse was an inverted vee half-wave dipole. Both antennas were > > supported from the lighthouse balcony (at about 40m!) and detuned when > not > > in use. An Yaesu FT-1000MP was used, running less than 100W > > > > Unfortunately conditions were poor during our evening time into North > > America, but at about three hours before sunrise the 160m band opened > into > > Europe. Right from this point, the vertical was slightly down on the > > inverted vee by a few dB, but I would always call on the vertical first > and > > then switch onto the inverted vee if I got no response. All the way > until > > just after sunrise, the inverted vee outperformed the vertical, mostly > > raising the stations who did not hear us on the vertical. > > > > The only time this situation was reversed was when 160m started to go out > > as the sun started to rise and I had by then switched over to just > calling > > stations on the inverted vee. > > > > After about five minutes of this, the Europeans I could still hear were > > not coming back to me anymore. Out of curiosity, I switched to the > > vertical – and found I could still raise a few of them. I recall vividly > > the last QSO with a CT1 using the vertical about 20 minutes after > sunrise, > > exchanging 559 reports. > > > > The crazy thing is that the vertical appeared to be doing exactly what a > > dipole is known for doing on 160m in the northern hemisphere in some > cases > > – extending the sunrise opening. However, this was the only time the > > vertical outperformed the inverted vee. > > > > As far as I know, Mike VK6HD never experienced this phenomenon when he > was > > comparing his inverted-L quarter wave antenna against his inverted vee > > dipole. However, my vertical antenna was directly adjacent to the sea, > > surrounded by sea, which may have helped. > > > > The final event was highly interesting, but did not sway me into > repeating > > the experiment the following year when I also operated from the > lighthouse > > in the Stew Perry TBDC. > > > > The fact was the inverted vee had been responsible for 80 to 90 per cent > > of my QSOs - can’t remember exactly how many – while the vertical had > only > > accounted for three or four. > > > > Mike VK6HD, Phil VK6GX and I are not the only ones to have experienced > the > > “verticals aren’t always best for DX” situation here. About five to ten > > years ago, I understand a group of German DXers came here and operated in > > the CQ WW CW (I think). > > > > The group operated from the the Northern Corridor superstation > > VK6ANC/VK6NC, using a quarter wave vertical on 160m. After disappointing > > results, one of the ops (Mar DL3DXX, I think) recalled Mike, Phil and I > > used inverted vees at 90 to 110’ and suspended a inverted vee dipole as > > high as they could and changed over to using this. My understanding is > then > > they found they could work a much larger amount of DX stations on 160m. > > ... > _________________ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
