My 4 Square Summary!

Attention: nobody is perfect, there might be mistakes. Thanks for an email with corrections,This page was created to note important facts concerning 4 squares. I read a lot, but I also forget a lot.
So I started to write down "all about 4 sqaures" to remember me from time to time. Please read ON4UNs book and other sources to learn all about 4 squares.
I try to add links to other great 4 square articles on the web.

I started at 1996 with G0NVD, G4OFY, G3FPQ working DX and working on my 4 square. Jon, G0NVD was a great teacher, sorry I was too lazy :-).

Since 2010 I have found that Franz DF6QV lives very close to me. He was the guy who build the 4 squares for

TS7N, 5A7A, TF7X, VP6DX. read his article about 4 squares!

Also big thanks to Uli DJ2YA and Peter DF3KV now DJ7WW, both are a great help for me building my antennas!!!!
I am really not an antenna expert but I hope this page is helpful for others. I try to explain in simple words, not with difficult formulas.....

I bought the house and garden east of my tower in January 2011, so now I have some more space to play with antennas.
At least the 80m 4 square radials are better to handle.

1. A (classical) 4 square consists of 4 quarterwave long verticals, spaced a quarter wave in a four corner arrangement.
300.000/3750khz = 80m wavelength / 4 = 20m = quarterwave
diagonal/Across = a^2+b^2=c^2 -> sqrt(a^2+b^2) = 28,28m across or 14,14 m radius

2. All elements are fed at the same time, (with different phase angles)

3. it fires a) through the corners ( 1 leading element + 1 lagging element + 2 elements combined as "a fat element" in the middle or b) "broadside ( 2x2 arrangement, 2 pairs of phased verticals)

4."classical" phase angles are -90 degrees (lagging), zero degrees (the two elementin the middle) and +90 degrees (leading). Hybrid - this is was Comtek offers.

5. for better/best performance you may build your own phasing network to adjust phasing angles to a maximum forward gain or front to back or a combination. att: you may need a more complex switching unit
because the beamwidth is now narrower than 90 degrees Remember, that more components can cause more faillures. One who has an excellent setup with great success is Paul. Look at PA0GMWs 4 square, which is in my opinion the best developed one in EU (individual phase angles, plus terriffic QTH (salt march land, good ground, flat terrain)

6. The network/hybrid is located in the center of the square. I use 3*lambda/4 RG59 75 Ohm coax so I can bury the coax and have the Hybrid in the shack, that is easier to maintain, check, .....
I don't feel I have too much additional losses because of the longer Coax. One can choose better coax (fewer losses) than RG59. I had plenty of it and it was cheap, so I used it.
Maybe one day I will change to better cable or use quarter wave long coax and put the Hybrid in the center of the square.

7. The feedlines to the verticals

You can use 50 Ohm or 75 Ohm cables for the feedlines. As far as I understand, it is better to use 75 Ohm cables, but 50 Ohm cables will also work. At another site was said, use 50 Ohm when ground radials, use 75Ohm when elevated radials are used. You need a current balun to prevent the coax from radiating when you are using elevated feed points!!!  Do not try without current balluns! You can order them at www.dxengineering.com  or www.dx-wire.de and some other shops. I got mine here in DL from dx.wire. They also have telescoping fibreglass masts for the 4 square and ropes,......

There are 4 feedlines to the 4 verticals. (all fed array) with a length of 90 degrees / quarterwave.
ATTENTION you need this in ELECTRICAL length, not mechanical! So do not forget the VELOCITY FACTOR of the Coax. 300.000 / 3750khz = 80m / 4 = 20m * VF(velocity factor) = 16,60m with Aircell7 (0,83 VF)
RG213, RG58 and RG59 mostly have 0.66 VF. so the cables are 20m * 0,66 = 13,20m long. oooops, that is TOO short. you will not reach the verticals (see fig. 1 where the radius is 14,50m!)

You need another coax e.g.: Aircell7, compare:

OR

If you have no chance to get Aircell7 or want to use the very cheap RG59 or RG58, you may use
3*quarterwave lambda cables which is 300.000/3750=80/4=20*3= 60m * 0,66velocity factor = 39,60m long cables (you need 4 of them, one for each vertical)

The best choice (quality) would be Aircell7 rather than using a very long coax (3 wavelength RG58/RG59/RG213). If you want the last fraction of a db, go for a cable with 0,8x velocity factor.
For some reasons you might want to use "longer" cable. In my case, I can hide the cable better and my garden ( where I have guests of my hotel) looks a little nicer.

For cutting the right length, please calculate the cable length PLUS about 2m more and then measure properly.
However, when I calculated and then measured the cable I always came very close to the calculated length.
Most important is, that they have the same ( electrical ) length. Normally, if you take all cable from the same spool, they are also the same mechanical length.
Do not use cables from different manufacturers or model/make. Everything you build (vertical, feedlines, loading structures, ) should look the same.

YOU NEED FERRITE CORES on the feedlines at the 4 verticals to let the radial and vertical resonate and NOT the feedline! (current balun)

8. The Verticals

there are many different types of antennas forms you can use. Classical and best is a fullsize vertical which is 20m tall (for 80m / 3750 khz). It can be a freestanding or guyed aluminium pole or a wire attached to a tree. you may use sloping verticals hung from a tower (the more vertical the wires are, the better the performance). you can use loaded verticals, the must not be fullsize! It depends on the loading form how effective the system will work. Try to avoid base coil loading! That has the highest losses. Try to use top loading, like an inverted L. Use centerloading with coils with a Q of 200,300 or even better. I use center coil loading at my 80m 4 square. If the Q is good enough, there is not too much disadvantage towards Inverted L loading. If you want the last fraction of a db and can not use fullsize elements, use Inverted L elements or even better T elements because then the high angle radiation of the horizontal wire will be cancelled out.
"Fat" aluminium poles are better (broadbander) than thinner copper wire verticals. But they are more expensive and takes longer to construct.
You can NOT use grounded towers with omega or gamma match. This will not work! (or at least you will get mad before you get the phase angles right,)
When you build your vertical, try to build them all the same dimensions! Same length, same loading, same coils etc! Later you can fine tune the resonance frequency with the length of the radials. Also CW/SSB band part switching is done by inserting a biece of wire (stub) or coil in the RADIAL. (much easier to construct and maintain)

Whenever I could use ground radials, I would use ground radials. Plenty of them. The problem with elevated radials is, that they can interfer/interact with other antennas / radials around, which is not the case with ground radials. If you go on dxpedition, have a QTH on the beach: 1 radial is enough, 2 are better because of NO horizontal radiation.

9. The Radials
Maximum performance: use 120 quarterwave long radials, under EACH vertical. This is what is tested and calculated the "best" ground. Use broad bus wires to connect radials, where they cross each other.
A 4 square will work also with less (ground) radials. Remember: the better the ground the fewer radials are neccessary to get maximum performance.
for temporary use or where ground radials are not possible, one may try with elevated radials. The simplest way is 1 radial per vertical installed "outwards" from the array. Raised 2-6m (80m array). ON4UN has installed his 4 square ABOVE the radial field of his 160m vertical. When you live near the sea or can install your 4 sqaure right at the beach you will not need more than just a single elevated radial.

Elevated radials must be resonant. Ground radials must NOT be resonant.
You may even use loaded/shortened elevated radials! Use let's say 4 short radials ( some say, up to two-thirds is no big difference to fullsize) per vertical and use ONE coil (with high Q) per vertical to get them to resonate at 3650MHz.

How shall I build my elevated radials ?

They shall not interact with other radials --- symmetrically, so they cancel the high radiation out
They must be loaded the most effective way if not fullsize --- good coil, or endloading (like a laying L or T). DF6SJ states in his excellent book "monopol und vertikalantennen" that if using a common loading coil with Q>300 you will not notice a diffrence compared to fullsize element/radials. But use a common coil for all radials per each vertical (= 4 coils) not a single coil per each radial (16 coils)

haveing enough space, it is not a big deal to build a 4 square nowadays.....you may order everything plug&play from www.dxengineering.com (Comtekboxes) if you are satisfied with -90-0+90 angles and "standard" gain...
.if you want a killer 4 square like PA0GMW and others, you will have to build your own phase network with 8 directions and: you need excellent ground and terrain and no neighbours.

My personal problem is, how must I build the radials so they do not interfer and have the best shape for the best pattern......
Also, haveing the building right at the edge of the 4 square (2 antennas mounted at the side of the building) I must use elevated feedpoints or most of the power will be radiated INTO the house...... remember, we are current feeding the verticals.
Current means "radiation" so most of the energy is radiated at the lower part of the vertical. the higher you are at the vertical, the less the radiation ( at quarterwaves). so the lower parts should be above any object near to to.
A vertical in your backyard surrounded by walls will not radiate very well

Finally I decided to build my radials as mentioned in the article of OE3REB (see link below). He recommends 1 elevated radial which is folded back so the radiation cancels out and there is no radiation from the Radials so only vertical radiation (low take off angle) from the vertical part and NO (horizontal, high angle) radiation from the radial. It is easy to tune and is roughly 8m into two directions = 16m wingspan. Because of the smaller footprint it might not interact so much with other radials and antennas around. I found this to be the best solution for me. I would use the same solution being on a beach front.
I use a relay and a 1000pf doorknob capacitor to switch from CW to SSB. So I tuned the radials to 3420khz. Each vertical must be tuned while the other three verticals are "left floating". (pull the coax off). Otherwise the will couple into each other while tunig......they will couple into each other later and they have to do so! Otherwise the 4 square will not work.

so tune each single antenna to 3420. When connected to the hybrid they will interact and the resonance frequency will shift up about 100khz, so then you have your array working in the CW DX window.
to shorten the antenna for SSB part, try a 1000pf doorknob capacitor. It is current maximum, you do not need vacuum capacitors but take good care of the conections and wires (high currents!)

Again: elevated radials will work, but you can run into trouble when they interact with other antennas or other radials of the array. If you can better try ground radials. You might save time when you have to put up 4radials only but then the trouble starts and you can be sure that 60+ ground radials will work good to excellent.

important Links with 4 square topics