ARLA/CLUSTER: LFA ou DK7ZB ?

[João Costa > CT1FBF]

---------- Forwarded message ----------
From: Antonio Matias <ct1ffu  gmail.com>
Date: 2012/10/11
Subject: Re: [CT-Com. & Tec.] LFA ou DK7ZB ?
To: ct-comunicacoes-e-tecnologias  googlegroups.com


Não.
na realidade as LFA não ficam nada bem na foto.

    *In the last time it comes into fashion to compare "old" and "new"
designs by other designers. Normally I would not share this discussion, but
in this case I must make an exception.*

*G0KSC claims his 1-lambda 50-MHz-LFA as much better. Indeed the LFA has a
greater bandwidth (which you do not need for CW/SSB/beacons). The LFA has a
better pattern ("Low-Noise"), especially the bigger vertical sidelobes of
the DK7ZB-Yagi are criticized.*

*But in the real world you have not  free-space conditions. If you mount
the Yagi above real ground, the sidelobe disappears by ground reflection
influence (see picture down). Do you believe the upper sidelobe, pointed
into the sky receives any "mystic" noise (from aliens, or what)? Or the
horizontal forward sidelobe with is suppressed  -25 dB?*

*Now compare the gain of the two Yagis with the same boomlength:*

*5-El.-DK7ZB 9,6 dBd, 5-El.-LFA 8,9 dB*
   *In the real environment you cannot see anything from a sidelobe pointed
downwards !*

*But a difference of 0,7 dB gain for the same boomlength of 1 lambda is a
really big one.*

*22 years of my own DX-experience on 6 m show the effectivity of high-gain
Yagis. The simple to built 5-El.-Yagi is still a good choice!*


No dia 11 de Outubro de 2012 13:48, Filipe Lopes <ct1ilt  gmail.com>escreveu:

> Cheira-me que este site foi feito por algum "amigo" do Justin...
>
> FL
> CT1ILT
>
> 2012/10/11 Antonio Matias <ct1ffu  gmail.com>
>
>>  Interessante site, onde ambos os desenhos são analisados.
>> Será que a LFA é assim tão melhor em relação ás yagis convencionais?
>> Vai ter uma surpresa.
>>
>> http://www.rwpenfold.co.cc/
>>  Antenna Engineer Investigates G0KSC's LFA Loop Fed Array & DK7ZB's Yagis Science,
>> it's matter of opinion!
>>
>>
>> My name is RW, I'm a retired *Telecommunications/Antenna Engineer*
>>
>> with over 50 years industry experience and for my hobby now enjoy
>>
>> Short Wave Listening and travelling across the globe!
>>
>>
>>
>> --
>> António Matias
>>
>> CT1FFU - CR5A
>>
>> www.dxpatrol.com
>>
>> QRV: HF, 6m, 4m,2m,70cm,23cm
>> SSB, CW, MGM
>> DX, EME, Contest,Sat.
>>
>> POBOX-38
>> 2504-909
>> Caldas da Rainha
>> Portugal
>>
>> --
>> Para mais informações/opções visite o site, e edite a sua conta:
>>
>> http://groups.google.com/group/ct-comunicacoes-e-tecnologias?hl=en?hl=pt-PT
>>
>
>
>
> --
> Regards/Cumprimentos,
> Filipe Lopes CT1ILT aka CR6K
> http://www.rep.pt/ct1ilt
>
>
> --
> Para mais informações/opções visite o site, e edite a sua conta:
> http://groups.google.com/group/ct-comunicacoes-e-tecnologias?hl=en?hl=pt-PT
>



-- 
António Matias

CT1FFU - CR5A

www.dxpatrol.com

QRV: HF, 6m, 4m,2m,70cm,23cm
SSB, CW, MGM
DX, EME, Contest,Sat.

POBOX-38
2504-909
Caldas da Rainha
Portugal

-- 
Para mais informações/opções visite o site, e edite a sua conta:
http://groups.google.com/group/ct-comunicacoes-e-tecnologias?hl=en?hl=pt-PT
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