# Phasing a Half Square

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by W5DXP, Apr 6, 2019.

1. ### W5DXPHam MemberQRZ Page

The half-square antenna is a broadside array. If the phase of the current in the second vertical element could be changed by 90 degrees, it would become an end-fire array. Has anybody ever turned a half-square into an end-fire array?

I guess not.

3. ### KK9WHam MemberQRZ Page

My question is how would you accomplish it? I have been looking at half squares recently.

4. ### K1LHXML SubscriberQRZ Page

End fire from two verticals spaced 1/2 wave apart requires a phase shift of 180 degrees per the ARRL book.

I don't think its possible in practice with a half square, but in a few places I've seen it suggested you can put a 1/4 wave stub in the center of the horizontal wire to effect a 180 degree phase shift.

Modeling this in EZNEC you do indeed get a 180 degree phase shift between the vertical sections with a 1/4 wave stub in the center of the horizontal wire - confirmed by looking at the currents tab. However the radiation pattern is almost omni-directional, and its no longer a low angle DX antenna, more a cloud warmer. I think what's happening is the radiation in the top horizontal wire is no longer cancelling and its radiating.

Only spent a few minutes looking at this, someone else might be-able to offer more, or correct what I think is happening

I used a half square on 40 meters with the 1/4 wave stub about 35 years ago and it seemed to work OK. I had a switch at the bottom of the stub to open or close it and change the pattern. Seems like I saw this in a 73 magazine article back in the late 70's.

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6. ### KK9WHam MemberQRZ Page

Thank you for the info. That will give me something to search for while in the shack this weekend.

7. ### K1LHXML SubscriberQRZ Page

I did find this:

132 - Double Bobtail Antenna for 20m

Setting #1, three verticals spaced 1/4 wave apart - this is not a Bobtail Curtain, these are Half Square with an extra segment, the spacing between the vertical elements is still 1/2 wavelength except with 3 verticals making the top wire 1 wavelength long. Having three in a row compresses the lobe more, narrowing the beamwidth further which increases the gain. The Bobtail needs to be fed via the center vertical at the top (direct coax connection) or bottom (voltage fed) otherwise the pattern becomes distorted because currents are no longer symmetrical.

Setting #2, that's a Half Square with the 1/4 wave stub in the middle, but EZNEC doesn't agree with that.

Setting #3, I think they're isolating the middle vertical all together, if that's the case EZNEC doesn't agree with the pattern shown, more a pair of kidneys or a 4 lobed pattern.

If this does actually work as described/assumed then I'm missing something, and need to be enlightened

8. ### K1LHXML SubscriberQRZ Page

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9. ### HOUND189QRZ Member

I'm amazed.. but no. You see, this is a perfect question, and (love) like forums. But, for entertainment how do you get past 'the dipoles. Ok... I put a technical thread of similar character and low-gremlin (behold) I got no replies. thread- uW antenna diy ...etc. Anyhow besides being a an nuclear fusion forum alumni and past confidant from anything to lasers.. my humble bow'nsess from your might, forum. thnky

10. ### HOUND189QRZ Member

I love the square ...any btw. And definitely consider the phase and reflector setup.
I have more...