Hi Rich,
if you feel like an alligator, then your antenna system is definitely
efficient, but an efficient antenna system is not always the best possible
one in term of S/N. (i.e. a beverage is unefficient but has good S/N)
Although relative S/N and reception can be antenna dependent, the main
limit is mostly set by peculiar features of a site that can be inherently
noisy or quiete, independently by antenna setup.
If something can be done at receiving site improving F/B and F/S,
narrowing the lobe and selecting it on the vertical plane, most of the times
the real core of the problem is anyway at the other end, and it's so big in
term of poor efficiency that whatever antenna or array you arranged to
minimize local noise and select best angle of arrival, the correspondant
signal will remain even below band noise.
The average people (those ones replying to an N5 or I4 calls) infact use
less power you have and often marginally efficient antennas like most of
the cheap strange objects advertized (and sold) as excellent performers.
(Hams are prone to believe in miracle antennas even if they are heavy and
expensive, but definitelly there is a preference for cheap and small ones)
Even a good multielement yagi can be a very unefficient radiator at some
angles when the owner didn't keep the right height from ground. In the high
part of the HF spectrum, infact, were extremely low angles are typical, this
losses can easily be 10 to 30 dB higher than in your stack, and in a such
situation it's obvious that a 2way QSO could be not possible anyway.
Generally speaking a stacked array has more flatness in gain and F/B,
covers more elevation angles and, with the possibility to select antenna
heights, should be more flexible and outperform a single yagi of double
elements in most of the cases.
73,
Mauri I4JMY
-----Messaggio originale-----
Da: Richard Thorne <rthorne@tcac.net>
A: Tower Talk (mail list) <towertalk@contesting.com>
Data: venerdì 23 luglio 1999 20.40
Oggetto: [TowerTalk] Yagis and Receive Strength
>
>Hi Guys:
>
>I've been working pretty hard on getting my transmitted signal
>improved. I have stacked F12 C3's (45' and 75' which appears to be a
>good compromise distance) and a new Acom 2000A Amplifier was just
>installed.
>
>Well things are good and I feel like an alligator. On 15 the other day
>I had a good pileup going, but I couldn't hear most of the stations
>calling. I'm not sure if thats due to the power and antenna types of
>those stations, or if I need to continue improvements on my end.
>
>So heres my ignorant question (kind of embarrassing too), does a larger
>yagi, i.e. going from 2 elements to say 4 elements improve receiving as
>well as transmitting? While I'm only stacking 2 Force 12 C3's (which
>gives me 2 elements on each band times two) it seems to me that I'm
>improving my receive capability better than I would with a single
>antenna with 4 elements on each band.
>
>I would love to stack a pair of C31XR's but I would have to get a 40
>meter beam and I'm sure this exceed the limits of my 25g tower.
>
>Whats the multitude think?
>
>--
>73,
>
>Richard Thorne - N5ZC (EX. KA2DSY, N2BHP, WB5M)
>Amarillo, TX
>http://www.tcac.net/~rthorne/
--
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