[TowerTalk] Re: Can takeoff angle be too low?

[i4jmy@iol.it]

This is only a personal thought developed in 23 years of contesting, 
but who has very peculiar installations generally opens and closes the 
band, is generally stronger at any time, and often is "the only signal" 
from his area .
When the antenna is very high from ground, althought peaks and nulls 
should be a number, it looks instead as every angle is well covered and 
nulls are not present. I attribute this to the fact that ionosphere 
layers and reflections are produced in rather wide 3D areas and not in 
discrete points, therefore the arrival of the angle rarely can be 
exactly in a null, of course if the null amplitude of the antenna 
system is actually very narrow.
The "very high" antenna expression covers those peculiar installations 
where not the tower but an hill top or a tall cliff fall establish 
waht's the real antenna height in terms of many WL from ground.
In such conditions the signal mess in wide open conditions is huge and 
sometimes a very low antenna that can't benefit the geographical 
situation helps in favouring higher angles and allows reception. 
I suppose this fenomena to receive better with a lower antenna is also 
caused by other factors, including that a number of correspondants do 
not have antennas high enough to efficiently radiate at low angles and 
when one can receive them it's only because a multihop condition is 
also present.
It's also perfectly possible to have a wide range of angles available 
using a stack, but if the useful angle to receive for a stated station 
is very peculiar this kind of antenna, when no provision is made to 
select the best antenna, the system may actually ruin S/N, like when 
one has gain but fair or no F/B and QRM is big at the back.
It's anyway a constant evidence in my records that low anglers open and 
closes propagation and that stations with system radiating at very low 
angles are 90% stronger if received with low angle system, 
independently if a propagation allowing more hops is present.
Another evidence for me is that beyond 9000 Km paths (like W6 or JA 
from here) antennas with medium high angles are totally uneffective in 
the very most of the cases.  

73,
Mauri I4JMY


> ---------- Initial message -----------
> 
> From    : owner-towertalk@contesting.com
> To      : TOWERTALK@contesting.com
> Cc      : 
> Date    : Mon, 18 Dec 2000 06:11:36 -0600
> Subject : [TowerTalk] Re: Can takeoff angle be too low?
> 
> 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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