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Author Topic: Cubicle Quad antenna or believe to be  (Read 2204 times)
2E0BSS
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Posts: 85




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« on: August 23, 2007, 04:40:38 PM »

I'm thinking of building an antenna for when i go out in the car. Ive been told it's a cubicle quad as it's a 4 element square antenna if that makes sense.

I've been told that the antenna is built to half a wave over the 4 elements so 20m would work out to 1.25m each side. Although the antenna is a bit more than 4 diamonds on a bar it's 4 diamonds but in each diamond there are smaller elements to make a spider web config on each element.

Have I been told the correct info or not? If someone can let me know I'd be happy so I can start to build

Charlotte 2E0BSS
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KE3WD
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Posts: 5689




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« Reply #1 on: August 23, 2007, 06:46:34 PM »

Here's a patent on a description likethe one you gave:

http://www.freepatentsonline.com/4229742.html

United States Patent 4229742

"A Cubicle Quad antenna having radial spider arms on a boom, a plurality of wire elements on each spider arm, with each element encased in a non-conductive material rod, and a ball-and-socket joint at each corner of each element-rod where it is secured onto a spider arm, so as to permit a wind or weather caused movement of the antenna and its element-rods without causing a breaking of a wire element at each corner thereof."

Here's another online reference I found:

http://www.wikipatents.com/4249185.html

Inventor(s)

De Cesari; Robert J. (3941 Mt. Brundage Ave., San Diego, CA 92111)

Abstract


"A portable and collapsible supporting structure for a multi-element quad antenna comprising a horizontal telescopic boom upon which are mounted several sets of folding spreader arms radiating from the boom, each arm being pivotally connected to it. Each set of spreader arms can be immobilized in a common angular position with the boom, whereby several quadrangular loops may be hung between said spreader arms. The boom is supported by a multi-element mast. The mast itself rests on the hollow cylindrical base which doubles as a sheath for the storage and transporation of the various dismantled elements of the structure."  


In my book that would make the description a Loop Antenna, and I would call it a "Quad" but not a "Cubicle Quad".  Semantics?  Don't know.  

Don't know the "proper" terminology actually, but I've always called loop antenna that uses radiator plus director and reflector of the appropriate dimensions and spacing a "Cubicle Quad".

Of course, if your "spider" reference is to something else, then I'm way out in left field.  


KE3WD
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WB2WIK
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Posts: 20611




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« Reply #2 on: August 24, 2007, 09:41:27 AM »

A cubical quad (not "cubicle") looks like a cube, i.e., it has six "sides" all the same geometry.  Only a two-element quad can look like that.  Once you get to three, four or more elements, it's no longer cubical, but it's still a "quad."

A 20m quad isn't 1.25m per side: Where'd you get that?

A quad loop is approximately one wavelength in perimeter.  Usually the driven element is just slightly more than one wavelength, the reflector is slightly larger still, and any directors are slightly smaller: But they're all "about" one wavelength in perimeter, which on 20m is about 67 feet (at 14.150 MHz), so each "side" is 67/4 = 16.8 feet, or about 5m.  That's "per quad loop."  A four element 20m quad would have four quad loops about that size, separated by .1 to .15 wavelengths between any two, so it's typically about 25 feet "long" (boom length, from reflector element to the second director element).  This is a pretty big antenna.

Were you talking about a *TWO* meter (2m) quad?  That's a more reasonable antenna to take portable/mobile...

WB2WIK/6
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KG4RUL
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Posts: 2734


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« Reply #3 on: August 24, 2007, 09:21:59 PM »

If Dilbert were a Ham, would he use a "cubicle" quad at work?
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WB6BYU
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Posts: 13334




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« Reply #4 on: August 25, 2007, 10:13:33 AM »

Indeed, I was sitting in my cubicle at work thinking about cubical quads...

I suspect the description you remember is not quite correct.

I often use a cubical quad for 2m on my car, but that is about the lowest
band for which it is practical.  This antenna is about 20 inches on a
side and about 14 inches long - close to a cube, but not exact.  That
is for 2 elements.  I've used versions up to 5 elements long, but they
need a much stronger support if you are going to use them at highway
speeds.  Many of the transmitter hunters in southern California use a
4-element design developed by the late K6OPS and published in K0OV's
book on transmitter hunting.

An excellent description of quad antennas by W4RNL is found here:

http://www.cebik.com/quad/2mq.html

I've found that his 3-element design works as well as the K6OPS design
(who didn't have the advantage of computer modelling in the 1950's)
and gives me direct coax feed on a shorter boom.  In fact, W4RNL even
has a spreadsheet you can use to calculate optimized quad dimensions
by enterying the desired frequency and element diameter - look here:

http://www.cebik.com/trans/ant-design.html

(There are a number of "quad calculators" available online.  Don't trust
any of them that doesn't correct for the diameter of the element wire.)


There are other antenna variants as well.  While you can shrink a quad
loop to about half the original dimension (but with the same boom
length) and still have a usable antenna, you can't make a 20m beam
quite as small as you were describing.
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