Diamonds or Squares?

[Guest]

I have often wondered if there really IS a difference between DIAMOND or SQUARE loops for a quad antenna when it comes to polarity. 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.

 

[jonbah]

The ham beams use the X spreaders mainly for added strength, most are mounted below the booms. I've read that the X pattern will not allow as much ice to build up on the spreaders but I think this is a myth because ice will build no matter how those spreaders are laid out.

The Diamond is the recomended layout for the quads, not sure if its because of the pattern and the feeds.


This website has some good information on quads and yagis.

http://www.signalengineering.com/ultimate/index.html

Thanks good post
Jonbah
Radio User, Not Engineer

 

[Master Chief]

I have often wondered if there really IS a difference between DIAMOND or SQUARE loops for a quad antenna when it comes to polarity. 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.

This question came up again this weekend. I too am interested in hearing what everyone thinks out here. Opinions are good, but facts would be better.

 

[C2]

I thought that the largets area would yeild the highest gain.

A circle beats a square beats a triangle, but I guess the beam part of it makes it more complicated.

How about a pentigon?

 

[Master Chief]

Too much effort to build circles and pentagons. I don't dispute your claims, but for now, we are talking about diamonds and squares.

 

[W5LZ]

The particular 'shape' of a quad makes little difference as long as the largest area possible is 'inside' that loop. Short and squatty, or tall and skinny can change the resulting radiation pattern, and in some cases that may be what you want. But, in general, like 'C2' said, a circle is 'best', next a square, then a triangle, etc.
Polarization depends on where you feed the thing. Top/bottom means horizontal polarization, either side means vertical polarization. Feeding it somewhere other than those places means it's polarized some other way (no circular polarization though).
Quads are large enough at HF that practicality in construction plays a bigger part of it's shape than you might believe. A nice perfect circle would be great, but how the @#$$ do you do that and not have a 'mon$ter' hanging over your head?
Which 'shape' is best? Which ever suites your needs, and you like the looks of 'best'.
Multiband quads are as nice to have as any other multiband antenna! They also have the same 'draw-backs' as any of the rest of those multiband antennas, plus, mechanically, they get a little intimidating (as in heavy, wind catchers, sort of). Single band antennas tend to 'out do' multiband antennas in general. But when you start looking at the requirements of single band antennas (how many acres did you say you owned?) that 'advantage' may not be as much as you thought. Quads can be 'stacked' just like yagi's, IF you have the support structure that can carry them (PLEASE take pictures of that!). Otherwise, do like is usually done and stick those other elements inside the larger ones.
Most of it boils down to practicality. Not what's 'possible' to do, but what it's possible for ~you~ to do.
Wish it were practical for me to have one...
- 'Doc

 

[Master Chief]

We are still not talking about circles or triangles. We are talking about SQUARES or DIAMONDS!

Out of these TWO, and ONLY these TWO, what is more desired and why?

The square or diamond will both have the same size "area" so that is a mute point. We know that polarization is determined by where you feed the antenna, so that point is mute.

The main focus (focus now) is the way the antenna RADIATES that signal. Will a diamond send the waves off in a "half vertical, half horizontal (45 degree) angle or will it be flat (HORIZONTAL). Will a square be flat and vertical (depending on the feed point positioning)?

SQUARE or DIAMOND and WHY! Its OK if you don't know, but PLEASE keep to the question at hand!

I am assuming that the square gives you either true horizontal and vertical polarization. I am also assuming that the diamond gives you something in between. Its safe to assume that it HAS TO! I also assume that this is why the hams use squares. But I can be wrong.

Furthermore, its easier to suspend a diamond than a square. A square needs an "X" frame to support the wires and requires better strength to reduce sag. The "+" for the diamond doesn't. The hams will usually spend more $$ to pay for the more expensive antenna. CBers won't so they make their quads as light and cheap as possible. Again, this is my assumption.

I can get into more specifics if you like, although I AM NOT A STRUCTURAL ENGINEER.

So......again......ad nausium......what do YOU think?

 

[C2]

The square or diamond will both have the same size "area" so that is a mute point.

Negative, Private!

The diamond will have less area, always, and have less gain, always.

Now, the square can be oriented with its wires going vertical and horizontal, or set on a corner, is that what your question is, or your interpretation of a diamond? Or does the diamond have 120 degree and 60 degree angles?

"We know that polarization is determined by where you feed the antenna, so that point is mute.

Will a diamond send the waves off in a "half vertical, half horizontal (45 degree) angle or will it be flat (HORIZONTAL). Will a square be flat and vertical (depending on the feed point positioning)?"

There is no point or answer. It depends on conditions and where you need the signal to go. Besides, the polarization changes anyway, so the end result is random.

 

[Dave_W6DPS]

As W5LZ said, electrically there is no real difference between a square and a diamond--since in reality they are the same shape with the feedpoint rotated 45°, and the element rotated to give vertical or horizontal polarization.

The advantage I have seen to the "diamond" is that the feedpoint is at the corner, and the feedpoint and feedline can be supported directly by the brace.

A "square" is supported at the corners and fed a the center of a side or the bottom (usually). This means the feedpoint is supported only by the wire that forms the loop, and the feedline is run from there to the boom without support.

If fed with coax, a 1:1 balun can help. The balun can also be easily supported by the brace in a "diamond" shaped quad.

For smaller antennas it doesn't matter much for strength. I have a cubical quad that is made from 1/4" tubing supported by a single crossbar that is fed as at the center of a side.

Dave_W6DPS

 

[Captain Kilowatt]

Check HERE starting at fig.18 The debate over squares versus diamonds has been and will always be a long and heated one.Cebic says the differance is 0.09 dB. WOW! :roll: As for strength both sides have merit. The diamond has one support that has no bending forces as it stands straight up but it alone must support the weight.The wires will not sag and have a low spot for ice to buildup. The square has two arms supporting the wires but they must also act against the forces of gravity as they want to bend over.The wire at top and bottom will sag in the middle and may cause water to run to the low spot and freeze causing ice to build up. Note the word "MAY". In any event the differances if they exist are so slight it is not worth even considering.They will NEVER be noticed unless you are one of those that think an extra 0.5 dB is a huge differance and will allow you to talk an extra hundred miles.

 

[W5LZ]

'M.C.',
Forget the 'half horizontal half vertical' thing with a diamond shaped quad, just doesn't happen. The same two feed points, top/bottom or one side, determines polarization, not the shape of the loop. Is a circular quad circularly polarized? No. Same way with the feed point on a circular quad, top/bottom or one of the sides, horizontal or vertical polarization.
Why would you want 45 degree polarization?
- 'Doc

 

[Master Chief]

Now, the square can be oriented with its wires going vertical and horizontal, or set on a corner, is that what your question is, or your interpretation of a diamond?

Yes, so my original statement is correct, that they both have the same area. All the antennas listed have all 4 sides equal in length.

As W5LZ said, electrically there is no real difference between a square and a diamond--since in reality they are the same shape with the feedpoint rotated 45°, and the element rotated to give vertical or horizontal polarization.

If rotating the antenna 45 degrees doesn't change anything, then rotating it another 45 degrees shouldn't either. Right? Rotating the feedpoint 90 degrees changes the polarization from horizontal to vertical. See where I'm going with this?

Why would you want 45 degree polarization?

I don't. I'd like to understand the difference between the square and the diamond and why one service uses one instead of the other.

Check HERE starting at fig.18 The debate over squares versus diamonds has been and will always be a long and heated one.Cebik says the difference is 0.09 dB. WOW! :roll:

Thank You! I can't believe I missed this!

 

[W5LZ]

'M.C.',
Sorry, stated that wrong. Why would anyone want 45 degree polarizations? If, as is usually suggested, you 'gain' maybe 'half' of the losses of the opposite polarity, it also follows that you would loose maybe 'half' the 'gain' of a signal of the same polarity. I honestly don't see where anything is really improved. You gain some and you loose some. Guess it just depends on what's gained and lost? (Assuming, of course, that the 'tilt' really does gain you anything.)
I can see where changing polarization would certainly come in handy. And I can think of three ways to do that. A 'dual' type feed, a physical tilting mechanism (elevation rotor, couple of long ropes ('armstrong' method)?), or a second antenna. Each has it's own 'pros/cons'. Or a fourth option, let the 'other' guy worry about it. Which is probably what happens most of the time - lol.
- 'Doc

(This has already been one of 'those days' and it hasn't even gotten a good start yet. My 'tax lady' was two days late sending it in. Pray for mercy!)

 

[Seminoles]

(This has already been one of 'those days' and it hasn't even gotten a good start yet. My 'tax lady' was two days late sending it in. Pray for mercy!)

As long as the Tax Lady isn't your XYL they will have to deal with the IRS and pay any fines. ;o)

I read some where that a square Quad radiates from the upper and lower parts if horizontally polarized would be the top 1/4 length and the where it is feed at the bottom 1/4 length like having two driven elements in a Yagi 1/4 wave stacked above each other doing the same if it is vertical polarized cant find it now. Now for the Diamond it is like an inverted dipole V shaped I believe it said the whole wire length radiated being a 1/2 wave over a 1/2 wave which gives more gain then the 1/4 over 1/4 then there is the big but (not mine that is) but the diamond is like TV rabbit ears and you lose the gain because of it being at a 45deg. angle not good for the two popular polarization's but better at picking up circular polarization and this is where the little lose over the square comes in. No if every one would get on the same plane we would only need 3 antenna hand held, mobile, base. Of course there still always be the mine is better then yours :watusay

 

[C2]

In this case I still say it depends. I don't know why Cebik comes up with a difference in his modeling of the two, there must be some reason though, but like he said, it is insignificant.

It is like asking which is better, fedex or brown, or usps? It depends on a lot of factors.

I like the idea of being able to rotate a cubical quad is all dimensions. who knows, there might be circumstances with pointing it straight up would be better.

That is all were talking about, right? which way do I orient the same antenna?

BTW, if we are talking about a square, the diagonals make a +, just rotated 45 degrees. So the diagonals are the same for both a square and "diamond." Same antenna, just oriented different.

OK, so my geometry book specifies that a diamond should have different lengths for the diagonals-- <>