[TowerTalk] Re: Can takeoff angle be too low?
alsopb
alsopb@gloryroad.net
Mon, 18 Dec 2000 14:30:58 +0000
I think Dick has put his finger on one reason there seems to be
discrepancies between reporters.
That is the local terrain.
It is clear from YT that those on tops of high hills, favorably
sloping terrain, or high mountains will have much lower angles of
radiation for the same tower heights as "flatlanders".
It would not be surprising for the "hilltoppers" to see higher
antennas as being inferior at times. I think that is because the
angle is now so low that it misses most of the distribution of arrival
angles.
Bottom line, you can get the preferred radiation angle via tower
height, terrain effects or both. To generalize from one site to
another is confounding -- unless the terrains are similar.
You can investigate the effect of terrain on radiation angle through
the public domain program YT. You'll have to search for it. I have
long lost its location on the web.
73 de Brian/K3KO
Dick pechie - KB1H wrote:
>
> Here at KB1H we have a stack of Hy-Gain 105CAs. 84'/65'/45'. The top two
> rotate on the same mast and the bottom antenna is fixed on Europe. Using
> a WX0B Stackbox we can pick any single antenna, combination of any two,
> or all three. Usually we run the complete stack when running Europe but
> during non-contest times I play around. Many times the lowest antenna
> alone is the best antenna to Europe at midday. When you hear the
> tri-bander stations doing well then you can almost always predict the
> lower antenna is the antenna of choice.
>
> With almost 25dB of terrain gain towards Europe I suspect the usual
> poorer performance of the top antenna can be contributed to this gain
> and the installed height. I actually stopped my 20M tower at 90' because
> analysis said 120' was not as good!
>
> de Dick KB1H
>
> n4kg@juno.com wrote:
>
> > Here is more corroborating evidence that a LOW
> > antenna is sometimes best during daytime operation
> > on the high bands. In this case, N2IC/0 found a 6L10
> > at 45 ft was better than his high KT34XA stacks to Europe
> > on 10 Meters during the CQ WW CW DX Contest in November
> > where he set a new all time W0 record.
> >
> > Any other similar observations?
> >
> > de Tom N4KG
> >
> > >>>>>>>>>>>>>>>>>>>>>
> >
> > CQ WW SUMMARY SHEET
> > >
> > > Callsign Used : N2IC
> > > Mode : CW
> > > Category : Single-Op All Band High Power
> > >
> > > Station Used : N2IC/0
> > > QTH : Colorado
> > >
> > > BAND Raw QSOs Valid QSOs Points Countries Zones
> > > ___________________________________________________________
> > >
> > > 160CW 18 18 40 12 10
> > > 80CW 162 162 451 36 18
> > > 40CW 520 511 1483 85 31
> > > 20CW 624 616 1788 96 33
> > > 15CW 833 826 2380 112 35
> > > 10CW 1101 1079 3089 115 32
> > > ___________________________________________________________
> > >
> > > Totals 3258 3212 9231 456 159 -->
> > >
> > >Total Score : 5,677,065
> > >
> > >Equipment and Antennas
> > >
> > >Station 1 - Kenwood TS-950SDX + Alpha 76PA
> > >Station 2 - Kenwood TS-930S/PIEXX + Alpha 76CA
> > >
> > >Tower 1 - 120' Rohn 25G
> > >KT-34XA at 120'/65' in upper/lower/both stack
> > >
> > >Tower 2 - 120' Rohn 45G
> > >KLM 40-3 at 120'
> > >KT-34A at 115'
> > >6 el 10 OWA Design at 45' fixed NE
> > >160 meter half sloper
> > >
> > >2 phased 80 meter verticals with 4 elevated radials each
> > >
> > >600' Beverages NE, E, SE, SW, NW
> >
> > SNIP
> >
> > > Around 1600Z I noticed that I could run on 10 meters
> > > using the KT34XA stack, and listen on the other radio
> > > on 10 meters on the 6 element OWA yagi. So....
> > > I could do same-band 2nd radio S&P.
> >
> > SNIP
> >
> > > I opened up on 28001 at 1525Z, but was quickly chased away
> > > after 11 QSO's in 6 minutes. I didn't want to waste time finding
> > > a run frequency, so I went right to 28158 ! It was a good run,
> > > with OZ6PI and ER0ND being new mults. Today, I found that
> > >the 6 element OWA at 45' was much better than the stacked
> > >KT34XA's - On some stations as much as 2 S-units. I had never
> > > seen this much of an advantage for the low antenna before.
> >
> > SNIP
> >
> > > Steve N2IC / 0
> > ________________________________________________________________
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> >
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