Your opinion and comments on the Half Square antenna

Discussion in 'General Technical Questions and Answers' started by G0GQK, Feb 26, 2009.

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  1. G0GQK

    G0GQK Ham Member QRZ Page

    I've read a number of articles which have suggested that a Half Square antenna is a good wire antenna for producing the low angle radiation needed for DX. Perhaps there are antenna experts, makers and experimenters who have made and used one and could give me their opinion of its performance when compared to a vertical antenna.

    Kind regards, Mel G0GQK
     
  2. WB2UAQ

    WB2UAQ Ham Member QRZ Page

    Hello Mel,
    I experimented with the inverted U or half square. I constructed one for operation at 200 MHz - using 200 MHz to reduce its size so I could handle it inside and down in the basement and I taped it to a piece of cardboard. I was curious about its vertical radiation pattern and using the horizontal wire as a transmission line to excite the second vertical. I found the radiation to be in fact be well vertically polarized and also not impacted by proximity to earth. I also noiticed that if I brought the tranmission line off one corner in line with horizontal wire, it was not that critical as to how the wire sloped off plus there was very little radiation from the transmission line (no balun needed). By far most of the energy radiated perpendicular to the horizontal wire and centered on it. This explains why it there is little interaction with ground and the transmission line because there simply is not much energy heading downward or off the ends (good lesson to learn! If no energy goes off in a certain direction how can objects in the direction interact or disturb the antenna).
    I ran all of the field strength tests with signal generator level power (< 5 mW) and used an HP415 SWR indicator with diode detector attached to a handheld dipole also cut for 200 MHz with a balun at the center to isolate it from the tranmission line. I also used a directional coupler to measure the return loss (SWR) with the antenna at various heights above the floor (earth) and in proximity to other objects in the room.
    I had a lot of fun experimenting and testing. This was > 10 years ago now and I planned on building a full scale version for HF but I was layed-off from my job (HP consolidated their service centers to Roseville CA and I would never want to live in CA away from the rest of the family) and other better things came along.
    Cebik did some very interesting papers on the halfsquare and I think much of it is in the ARRL ant Compendiums.
    73, Pete
     
    KC9UR likes this.
  3. K7MH

    K7MH Ham Member QRZ Page

    Here is an article about a 40 meter half square built by my best friend Rick W7AV.
    He swears by the antenna. He is always trying to talk me into putting one up. I am just not that interested in 40 really. He also had a 40 meter 5 element bobtail curtain for a while but had a hard time keeping it up in the air!!

    W7AV 40 meter half square
     
  4. K4UUG

    K4UUG Ham Member QRZ Page

    half square antenna


    Mel The half square antenna has a beamwidth of about 60° and a gain of about 4dB so play with it and keep a log of sig reports and see if you get better reports.good luck have fun :)
     
  5. G0GQK

    G0GQK Ham Member QRZ Page

    OK fella's, thanks for the replies and especially Pete,

    The reason I asked for comments is because I made one for 30 metres last September, to the exact dimensions, fed in the top corner, if I remember, braid to the vertical, and centre conductor to the horizontal and far end vertical section. The SWR is as predicted, fed with RG58, but when I compare this to my vertical I don't observe any difference in signal strengths between stations 700 miles away or 3,000 miles in the US.

    Doing some reading I understand the antenna fires off 90 degrees from the wire, it doesn't fire off the ends of the wire, which is OK because the wire is approx. east -west heading towards maybe Iceland, Greenland, Alaska

    I also read that its essential to put about 6-8 coils in the coax to make certain that RF is not finding its way down the braid to affect its vertical radiation pattern, I don't believe it is but I intend to do this, and I dont have any radials laid on the grass under the vertical section

    The bottom of the vertical sections are just about touching the ground andI read that I can turn these 90 degrees and lift them above the ground a little more.

    Presumably they transmit as well as they "hear", every account I've read states how good they are, and your comments confirm this, so why is it I wonder why the one I made is not as impressive. Any ideas anyone ?

    Kind regards, Mel G0GQK
     
  6. G0GQK

    G0GQK Ham Member QRZ Page

    Oh dear ! It seems that there aren't any users of a half square antenna that I can compare notes with and try and improve it a little. Surely there's somebody in that huge country who is actually using one !

    Mel G0GQK
     
  7. WA9UAA

    WA9UAA Ham Member QRZ Page

    Hi Mel,
    Actually I'm not a user, but I would suggest getting the vertical ends up off the ground if at all possible. I'd worry about ground losses off the ends due to the high voltage points.
    73,
    Rob WA9UAA
     
  8. K4UUG

    K4UUG Ham Member QRZ Page


    A very good point many never consider ground loss or the high voltage points!!!:)
     
  9. K3STX

    K3STX Ham Member QRZ Page

    I have a friend who used one on 40 and on 20. They were great for DX, low angle radiation. Basically phased verticals. Also you don't need a ground system, they are a great antenna. I would have done it, but my trees are in the wrong orientation.

    You don't want it touching the ground, at least 6 feet would be best. The ends are very high voltage. And a coax choke would be good to prevent common mode currents. It is the nice low angle radiation of the vertical without the radials. A great antenna. Read the ARRL Antenna Book or Low Band DXing for info about phased verticals.

    paul
     
    Last edited: Feb 28, 2009
  10. G0GQK

    G0GQK Ham Member QRZ Page

    Hello again,

    Thanks for the replies. I'm not able to see a copy of the ARRL antenna Handbook in the UK, but I've read lots of comments after Googling. The ends of the verticals are above the ground and I've put five turns in the coax after the feedpoint. The antenna works OK but it still doesn't seem to be to be any more effective than my quarter wave vertical with quarter wave raised radials that I have on 30 metres and I'm just wondering why.

    Maybe there isn't a reason why, its just one of those things.

    Kind regards, Mel G0GQK
     
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