Re: [TowerTalk] RV: 6 mtr quad

["Joe Giacobello, K2XX via TowerTalk" <towertalk@contesting.com>]

Yes, Màximo, I should have mentioned that I designed for maximum forward 
gain.  I'm generally only interested in the CW end of the band and take 
what I get elsewhere.  (Nevertheless, IIRC, the gain did not drop off 
very much in the phone part of the band.) The problem with F/B on quads 
is that it peaks over a very narrow frequency range, so I just don't 
think there's much to be gained by designing for F/B, and I personally 
prefer to focus on forward gain.
73, Joe
K2XX

> Máximo EA1DDO_HK1H <mailto:ea1ddo@hotmail.com>
> Thursday, September 01, 2016 10:18 AM
> Hi,
>
>
> Any quad or Yagi is designed with a target on mind. You can't get 
> everything, so you need to focus on one of the three main parameters; 
> forward gain, rear gain (F/B), and bandwidth.
> You can only maximize two of them. Or you can leave all three 
> balanced, no one parameter reaching his top limit.
> Most commercial designs are "balanced", for average users.
>
>
> But if anyone wants to maximize his design, he is able to get much 
> better figures, just from two parameters.
> A good example is in the high bands, where bandwidth is not an issue, 
> due narrow band use (VHF). Then, you can design to get highest figures 
> on front gain and rear lobes, in a narrow bandwidth. Over only two 
> parameters.
>
> On HF bands things are a bit different.
>
> Newer quad designs for HF include what was called "OWA" style.
>
> Using a specific design technique you can get a balanced response with 
> higher gain and F/B than traditional designs.
>
> There are some designs (including 6m OWA) and documentation at; 
> http://www.ea1ddo.es/cubicas.html
>
> And hundred of quad pictures at; http://www.ea1ddo.es/galeria/index.php
>
>
> 73, Maximo
>
>
> ________________________________
> De: TowerTalk <towertalk-bounces@contesting.com> en nombre de Roger D 
> Johnson <n1rj@roadrunner.com>
> Enviado: jueves, 1 de septiembre de 2016 13:09
> Para: towertalk@contesting.com
> Asunto: Re: [TowerTalk] 6 mtr quad
>
> The big question is, over what frequency range and angles does this 
> F?B ratio
> hold up?
>
> 73, Roger
>
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> Rudy Bakalov via TowerTalk <mailto:towertalk@contesting.com>
> Thursday, September 01, 2016 8:09 AM
> It is worth taking a look at the Swiss quad described in the Rothammel 
> Antenna Book, which as far as I can tell was never for sale in 
> English. The Swiss quad takes the idea of the HB9CV yagi and applies 
> it to a quad to achieve over 30 db F/B with a lambda/8 boom. I have 
> personally used a few of the HB9CV yagis and was amazed by their F/B.
> The German version of the Rothammel book is available for free online.
>
> Rudy N2WQ
>
> Sent using a tiny keyboard. Please excuse brevity, typos, or 
> inappropriate autocorrect.
>
>
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> Martin Sole <mailto:hs0zed@gmail.com>
> Thursday, September 01, 2016 3:23 AM
> I've long been a quad aficionado and have generally devoured any 
> information I can find on them. The double driven W6PU quad is an 
> example of something a little different that suggests it can still be 
> a useful antenna. I still have a lightning bolt quad along with lots 
> of extra parts and hope to shortly rework it as a 3 element with 30 
> and 40 added to the other 5 bands together with moving the10 and 12m 
> elements to improve on their compromise positions. We'll see.
> But in all of this the information by Cebik probably stands out as the 
> most thorough examination of the quad and it's comparison with the 
> yagi array. My take away from his work is whilst the quad might well 
> demonstrate some gain advantages in some situations it suffers from 2 
> seemingly intractable issues. Firstly the gain, F:B and SWR responses 
> are somewhat more "peaky" than the equivalent yagi curves. Secondly 
> that these responses are less well aligned. That great 30dB F:B at the 
> CW end of the band matches to an unfortunate 6 dB drop in peak gain 
> whilst up in the SSB end of the band the extra bit of gain is matched 
> to a meagre F:B.
> I do think that the closed loop antenna tends to be lower noise, there 
> seems to be a lot of anecdotal information that makes this hard to 
> ignore and my own experience points to much the same. In SE Asia we do 
> get lots of heavy monsoon rain and there seems little doubt the quad 
> works better at those times.
> I definitely would agree that like the newer dynamic antennas the quad 
> really needs either a telescopic tower or one with a fast and 
> convenient raising fixture. The frailty of both these antenna types on 
> a fixed 80 foot plus tower is never going to be ideal.
> Martin, HS0ZED
>
>
>
>
>
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