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 <mikewate@gmail.com> 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 <vk6vz@arach.net.au> 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
|