The best gain/boomlenght ratio is against LP antennas were only some
elements, concentrated in a small boom area, are band by band active.
Generally, unless the antenna is designed to maximize flatness or to be
a reference tool for mesurements (VHF UHF), gain and F/B are far from
beeing constant along all covered frequencyes, expecially at the low edge
of their range.
The nature of an LP delivers a lot of unwantwed (by hams) out of band huge
signals (broadcastings) to the transmission lines and this is potentially (I
feel polite today...) damaging most of ham receivers performance.
An LP with an effective 6 dBd gain should have a pretty long boom, probably
close to the lenght of 3 monobanders yagi of that gain, one after the other,
plus the unavoidable weight of all the other LP elements catching wind and
BCs too.
Huge professional LPs (those on very big towers mainly used on marine or
PTP) have excellent performances on Ham bands but can't be compared in
size and weight with amateurs antennas.
In a strategical location and used by a top operator, a good LP can be a
winner in contesting efforts (like Jim, N6TJ at ZD8, if I'm not wrong).
73,
Mauri I4JMY
-----Messaggio originale-----
Da: William F. Beyer Jr. <n2wb@bellsouth.net>
A: ,Rtty reflector <wf1b-rtty@wf1b.com>; towertalk@contesting.com
<towertalk@contesting.com>
Data: domenica 25 luglio 1999 18.55
Oggetto: [TowerTalk] Re: yagis or log.
>
>
>
>WA9ALS - John wrote:
>
>> Some have told me that you don't see many contesting stations using log
>> periodic antennas. Is that true? If so, why? For example, the
>> Tennadyne T-10 claims 6.1 Dbd gain and 15-25 F:B. That certainly
>> APPEARS like it would be competitive with even the C31XR or TH11DX, yet
>> I don't hear about many using LPDAs. What's not apparent from the
>> numbers?
>>
>
>
>So, which is better? Log Periodic antenna or trapless Yagi?
>--
>
>73 & see you in the pileups!
>William/N2WB/KG4WB
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