Diamonds or Squares (again)?

[Master Chief]

This has been posted before. I never got a good answer.

I have often wondered if there really IS a difference between DIAMOND or SQUARE loops for a quad antenna when it comes to polarity and performance. Which one works better or are they both so close we would be splitting hairs.

The ham radio antennas seem to use squares while the CB world tends to use diamonds (Avanti, Maco, Signal Engineering, etc).

Aesthetically speaking, I like the "looks" of the diamond loops, but the square loops with the x-braces sure look BIG!

Feeding the diamonds have the advantage of using the spreader as a support for the feedline, where you usually feed a square in the middle of the loops rather than the corners.

I'm curious what YOU think!

 

[W5LZ]

Master Chief,
I think the biggest difference is in the 'mechanics' of it rather than any significant changes in radiation. A 'square' doesn't have to be quite as far off the ground as a 'diamond' does to have the same clearance (figuring clearance from the boom, not the spreaders).
I've modeled them both with an antenna modeling program and there was no significant difference in gain or in the radiation pattern. Some, but not enough to make any difference.
As far as the shape of a loop goes, the more area 'inside' the loop the more efficient it is. Circles are better than squares, squares are better than triagles, and so on. Now, if you could figure some way to put a circular loop up instead of a square or diamond.....
- 'Doc

 

[Master Chief]

Circles are better than squares, squares are better than triagles, and so on.

There is more area inside of a square than inside of a circle.

While installing a 55' tower, it was suggested we drill a 3' round hole instead of digging a 3' square hole. We actually had to go deeper with the round hole in order to keep the same mass of concrete for the base. Drilling the round hole was FAST and easy too! Digging the square hole goes one bucket at a time.

A circle is just a square with the corners chopped off!

Do you have a copy of the two models, I'd like to see what it says. Thanks for the info!

 

[Beetle]

I've used both. One caveat that has been batted around is that the diamond configuration tends to accumulate less ice and snow during severe winter weather because there are no horizontal surfaces. I've never lived where that would be a problem.

Right now I have a 5-band, 2-element, horizontally-polarized quad which has been up almost 12 years on a 52-foot tower. Haven't had any problems with it.

 

[Hamin' X]

When talking about loop antennas (one element of a quad), you are using one wave length of wire. This applies to circles, squares, triangles, or any other shape. The circle, by definition, encloses the maximum area for the minimum amount of circumference. Therefore, 36 ft of wire in a circle has more enclosed area than a square with nine foot sides.

Rich

 

[freecell]

good post Rich.

 

[W5LZ]

Master Chief,
I didn't save the files for the two loops, sorry. When I get a chance I'll do them again (don't hold your breath, my memory ain't what it used to be, but I will do them).
I didn't make myself as plain as I should have about the circle and square thing. It's per the circumference, and that's why round cakes are bigger than square ones.
- 'Doc

 

[RoadWarrior]

Living in a bad climate the diamond shape would be best.
Not to mention that large birds would less likely sit-on
a diamond shape compared to square.
Performance Difference: I don't know the true answer
to that question either.
I owned a Signal Engineering Quad last summer. Sold
it as it was very poor quailty. Performed great though.

 

[Captain Kilowatt]

Square vs. diamond has been debated as long as the quad has been around.The general concensious is that when mounted close to the ground the square has a slight bit more gain but that extra gain can only be measured with a field strength meter.The differance is so small that it woukld not be seen on the signal meter,typically 1 dB or less.The diamond will prevent ice build up better if that is a concern and makes it easier to attach the feedpoint however the spreaders will be subjected to high RF voltages especially if running high power.The square configuration has the spreaders supporting the wire at low RF voltage points.

 

[Master Chief]

I see my error; thanks Rich. Doc, I'll go bake a cake! :shock:

QRN's post about the high voltage points is also very interesting.

As far as the comment about no horizontal surfaces, this is not entirely true. One of the spreaders would be horizontal for the diamond shape and at a larger diameter than the wire. Of course the wire would probably fail before a spreader would.

I just find it strange that hams always go with Squares and CBers go with Diamonds.

Good input (from almost everyone)!

 

[Captain Kilowatt]

I just find it strange that hams always go with Squares and CBers go with Diamonds.
quote]

Maybe that is because the square actually has a slightly higher effective height (practical) whereas the diamond just plain looks cooler (eye candy).

 

[Marconi]

I agree with QRN, it probably has to do with the high voltage nodes and where they fall when fed at the current node on the bottom of the square. They do not have to deal with high voltages at the spreaders.

 

[EDUK8TR]

Circles. Hmmm, has anybody actually ever tried to make a quad type beam with round directors and reflectors? With the varied composite type materials available today I wonder what the feasability of such a project would be? Would there be any increases in gain in round v. square/diamond? Is it worth the pondering

 

[2M Guy]

There are circular quads. Can't remember who makes 'em, Google might tell you.

 

[jonbah]

A Hula Hoop Quad Antenna. Has possibilitys