Small Quad Antennas ?

[curlyjo]

I have been tossing around the idea of putting a 2 or 3 element Quad Antenna up on the roof. Been reading the radio forums about the commercial kits and home brew Quads. I am little confused with matching the driven element with 75 ohm coax and the direct feed method Don Butler-N4UJW uses on his version. It is not so much the math involved because of the online calculators. (The tuning part is not so much clear to me.) I see Homer put a project box on the boom. Don put's his on the bottom of the driven element with RG58. Not sure how CUBEX does it. Seen different pictures of the finished antennas, Not of the matching systems. Like the idea of saving money by building my own. Can buy locally for some of the materials. The rest I can get online. Like the idea of instant gratification of a CUBEX or LIGHTING kit. A 3 element does not seem to leave that much bigger of a foot print than a 2 element Quad? Can anyone shed some more light on small Quad antennas. Seems like everyone that has one likes it!

 

[nosepc]

I have been tossing the idea of putting a 2 or 3 element Quad Antenna up on the roof. Been reading the radio forums about the commercial kits and home brew Quads. I am little confused with matching the driven element with 75 ohm coax and the direct feed method Don Butler-N4UJW uses on his version. It is not so much the math involved because of the online calculators. (The tuning part is not so much clear to me.) I see Homer put a project box on the boom. Don put's his on the bottom of the driven element with RG58. Not sure how CUBEX does it. Seen different pictures of the finished antennas, Not of the matching systems. Like the idea of saving money by building my own. Can buy locally for some of the materials. The rest I can get online. Like the idea of instant gratification of a CUBEX or LIGHTING kit. A 3 element does not seem to leave that much bigger of a foot print than a 2 element Quad? Can anyone shed some more light on small Quad antennas. Seems like everyone that has one likes it!

The best quad antenna is a SWISS QUAD.

It needs no insulation, or reeds, or anything, is all welded to the mast!!!

I and 2 are constructed for years and am about to do a third.
Broke down because they did absolutely iron pipe plate for electrical connections.
The gain and directionality when properly adjusted is impressive, nothing compares to it, not even a 7-element yagi.
The only drawback is that when this set is very narrow band, about 12 channels, but I do not care, I just I operate between 27,400 and 27,500.

 

[Henry HPSD]

...nospec...you are getting a bit silly....
(beeing polite here).

..7el yagi equals 2el swiss quad / best quad ever.....

But of course, thats why we always use the swiss quad

@Curlyjo:

1- Best quad is the oblong in reverence to gain. (you can get more...but the loops would be beyond 1wl.)
The Swiss quad is a "normal" quad with a phased feeding system. Similair to the
hb9cv. Just google cebik and swiss quad, im sure he has written something
somewhere.
2- A quad does not produce a noticable lower take off angle, compared to a yagi at
same heigth.
3- Very small quads examples are: maltese quads or pfeiffer quads.
You could also get into: fractal quads. There is still somethings to explore
in those regions.
4- A traditional 2el quad will have a impedance that needs to be match to 50 ohms.
Normally this is done with a 1/4 wave matching stub (75ohms)
The gain is in the order of just over 7dBI and the boom around 1.5..2 meters (4.5..6
feet)
5- A 3el tradiational quad can have a 50 ohms direct impedance, but has in that case a rather small 2:1 swr bandwidth. (600/700 Khz) the gain will be around 9,2/9,3 dbI and the boom length in the order of 4 meters (12 feet)

I hope it is of use.

H.

 

[nosepc]

Henry HPSD

And you know that the swiss quad?
On the other hand brings the case what someone said about the antenna, reviews spins in the air.
A Swiss quad could not compare with the cubical quad, are very different.
The swiss quad has two loops in the same place at ground potential.

2- A quad does not produce a noticable lower take off angle, compared to a yagi at
same heigth.

The swiss quad is independent of the height.

Two rings are connected in the same place, and when you get resonance makes very sharp and strong way, its noise level is the lowest of all type of existing antenna, just like a magnetic antenna.
I used 3 of them, two of mine and a friend, also had yaguis, but the Swiss Quad is very different, much more directive, more gain is obtained, its noise level is infinitely less' and also its width band is very tight. but this last one I do not care.

With $ 10 you can make a..

 

[Henry HPSD]

I know, cause i made several of them

Im afraid i dont feel much for going in discussion with you...


Kind regards,

Henry

 

[curlyjo]

Thanks you guys for the input. Going to look into your suggestions. Do not want to start a 30 page debate on the subject. Really don't care all that much about why it works. Just that it sufficient with my space limitations. I am a casual operator that likes to shoot skip in my spare time. Would like to put something up over a weekend that will last. For the record I do have a Sigma 4 knock off antenna that preforms very well for me. Do not really understand all that much about how it radiates. Just know it works! Want the same for a small beam. 2 element Quad could fit the bill. Anyone else want to jump in with their experience's with small Quads. Please do so. Thanks again you guys.

 

[HomerBB]

curlyjo,
I think Henry's reply says it all, but just for the sake of simplifying the 75 Ohm 1/4 wavelength matching jumper I'll add a little.
Because of my limited ability to raise really bulky antennas I've not ventured bigger than a 2 element Quad, or a 4 element Yagi at this location. The 2 element quad needs to be matched to 50 Ohms, as has been said.
this works out to about 5.93' for 27.385 Mhz using .66 VF cable.
I have found the easiest way to accomplish it is to purchase a 6' long 75 Ohm jumper and two adapters for the Video type connectors on the jumper to the PL type connectors from Radio Shack.
It is simple. This jumper is between the Driven loop and the feed line. Done.

Some prefer other methods of matching because it is said this type limits bandwidth. I, however, have plenty of 1.5 SWR bandwidth this way to operate in the range of frequencies I use.

Currently my beam in the air is a Moxon. It is a 50 Ohm direct coax feed that works very well, is easy to construct, and is weather hardy.

 

[curlyjo]

Thanks Homer BB! Enjoy reading through your projects. Like your Moxon. I read up on making jigs for bending aluminium to use smaller diameter tubeing for a Moxon. Enjoyed reading that one too! The Moxon / walker is the best! 73's