The half square is a simple antenna design thats been around for a longtime:
- Offers good low angle gain with out the need for radials.
- Little more than 1/4 wave high (40ft at 40m).
- Current nodes/maximums are up high, compared to verticals this should have less interaction with near by structures on the ground and reduce noise pickup.
- 80 degree beam-width, can be fed directly with coax at a corner, or voltage fed at the bottom of one leg. I coax fed mine and put a 1M (million) ohm 5W metal film resister across the feed-point to bleed off any static buildup.
- Only down side is the bandwidth is a bit narrow in the model, but in practice it was more forgiving.
More reading by people smarter than me:
- Part 4: The Open-Ended Cousins - Cebik
- Using the Half-Square Antenna For Low-Band DXing - N6LF
- Bob Tails and Half Squares - K3KY
I've had the antenna up for a few days, on JS8Call where I'm most familiar with what I can hear, this antenna has shown it's DX potential on 40m overnight, with more stations spotted across the Pacific than with the OCFD. Down side is performance (as expected) with closer in stations (~1000 miles) are weaker.
The SWR bandwidth is broader than the model, it's quite usable across 40m with it centered around 7.160 MHz.
Noise pickup is negligibly different compared to the OCFD, a stark contrast to the ground mounted 43ft vertical I had up a while back which was very noisy on receive in my city location.
If I had the room for more than one wire antenna I'd keep this one up, however it's a single bander. The OCFD is back up for now..
Models are good starting point, and a way to investigate and better understand antenna systems. These tools can also help guide us to and validate the final result, if a good correlation is observed in the real world then we can have confidence the patterns and other information are accurate.
The models I have created and made available may contain errors, or overlook something someone more experienced can see. I don't claim to be an expert or authority on the subject of antenna modeling or phased arrays. I simply want to further my own knowledge and understanding of antennas which I find fascinating. Comments, suggestions, discussion are welcome - lonney@gmail.com.
This post is one of several on Phased Arrays.