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The Quad Debate

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Martin, DK7ZB
Sun Feb 15 2009, 09:53PM
Martin, DK7ZB
Registered Member #788
Joined: Thu Dec 11 2008, 05:01PM

Posts: 7
If you are interested in a new type of a high-gain Quad-antenna, pse look on my homepage:



The "DK7ZB-Quadlong" is simple to build, has 6,4 dBd (8,55 dBi), 20 dB F/B and the DK7ZB-28-Ohm-match.

73 de Martin, DK7ZB
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Justin, G0KSC
Tue Feb 24 2009, 10:07PM
Justin, G0KSC
Registered Member #64
Joined: Thu Mar 20 2008, 04:10PM

Posts: 49
After Martin suggested that no good gains could be achieved (over and above Yagi's) with more than 2/3 elements, I decided to give them a go modeling with OWA Wideband 50 Ohm concept. Therefore, no complected matching is required, a coax balun at the feed point is as much as you need.

The results have been good with greater gains and smaller boom lengths than those required with OWA Yagis' I have posted on my site



[ Edited Tue Feb 24 2009, 10:07PM ]
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Martin, DK7ZB
Thu Feb 26 2009, 04:12PM
Martin, DK7ZB
Registered Member #788
Joined: Thu Dec 11 2008, 05:01PM

Posts: 7
Hi Justin,

your 3-Element-Quad is the best design for that type I ever have seen, congrats! I have proved several Quads I found in magazines and the web with 3-6 elements, all not real good...
A well constructed Quad with n elements ( n >3 and <7) is comparable with a n+1 element Yagi with a 20-30% longer boom. But we must see that each Quad-element has a dimension of 2x lambda/2, which makes 2 Yagi elements.

Built with "low coast" parts (wood, bamboo, wire) it is a real good choice indeed.

73 de Martin, DK7ZB
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Jan, OY3JE
Thu Feb 26 2009, 08:21PM
Jan, OY3JE
Registered Member #46
Joined: Wed Mar 19 2008, 09:11AM

Posts: 3
Hi Justin,

I find your desing of the Quads very interesting, and is this allso close to what I get with my very little knowledge to antenna design and software. I did use MMANA to make some examples based on my Quad antenna that is built by GB Antennas.
My current Quad is a 4el 4/6m and before that I did have a 2el 4/6m.
I thinks this type of antennas is the best awaileble for limited space as you will get a good perfomance antenna, short boom, NO static noise from rain/snow and you dont to go as high up in air as with a yagi.


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As you se on the design of this antenna, it's built of aluminium and fiberglas, and has this design proven to been very stong the first winther here, as we have very high winds here.


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Justin, G0KSC
Tue Mar 24 2009, 07:36PM
Justin, G0KSC
Registered Member #64
Joined: Thu Mar 20 2008, 04:10PM

Posts: 49
Thanks Martin and to you Jan too. The GB antenna looks well made, I was not able to model a multi-element dual band antenna with good gain and F/B on both bands. I had to insert additional directors between the 6mtr one for 4. I like the idea of the short stubs in the boom with the fibre glass end pieces, I might try this myself.

J
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Zaba, OH1ZAA
Tue Jun 02 2009, 01:22PM
Zaba, OH1ZAA
Registered Member #123
Joined: Thu Apr 03 2008, 02:54PM

Posts: 25
A funny variant of the "quad" is the one with two delta-loops back to back on a common boom as the driven element(s) and two linear reflectors (one behind each delta). It had very good pattern and gain. I published it as an URSI-paper about 12 years ago for 230 MHz DAB radio. However, DAB (Digital Audio Broadcast) was economically a fiasco in Finland and broadcasts were stopped at the turn of the century. I will try to find the original article and scale it for 50 or 70 MHz. As Justin/GoKSC states: just to play with it ---- 73, "Zaba" OH1ZAA/OHoMZA ---
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Zaba, OH1ZAA
Tue Jun 02 2009, 01:30PM
Zaba, OH1ZAA
Registered Member #123
Joined: Thu Apr 03 2008, 02:54PM

Posts: 25
Actually DAB transmissions ended here at the end of 2005. One reason I designed the loop feeders, is the immunity for rain static, also mentioned by Jan/OY3JE --- 73, "Zaba" OH1ZAA/OHoMZA ---
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