kc5uta
Member
Had a weird (probably over caffeinated) idea pop into my head the other day. What if you took a regular J-pole antenna, and bent it into a halo antenna?
So I did. I made a regular copper pipe J pole, tuned it to 1:1 swr at 144.5mhz. Marked the points, then hit it with the tubing roller, made it into a halo, that has a 1/4 wave tuning stub vs the usual halo gamma match.
things noticed:
1. it was it was no longer "flat " at 144.5, but now flat at 152.300 (ish) with some variation noted when changing the spacing with the loop ends (pretty much like a halo)
2. feed point stayed close to the same spot
3. horizontal orientation was omnidirectional ( no noticible signal strength change on rotation )
4. when oriented vertically and turned it was directional, I assume perpendicular to the loop.
Unlike a halo (a dipole center fed with a gamma) this one turned out to be essentially a 3/4 wave end fed loop (i guess) with a 1/4 wave stub.
That said, I have no idea what the pattern or effectiveness would be horizontal or vertical. tried google to see if there was anybody else that tried this design, see what they thought.....worthless.
all i got was stinking J-pole/slim Jim links, and ads trying to sell me loop or j-pole antennas, the further down i went the more off topic it became....google sucks :-(
next time I build one Ill make it about 15% longer +/- to account for the resonance shift, go from there. Dave Kc5uta
So I did. I made a regular copper pipe J pole, tuned it to 1:1 swr at 144.5mhz. Marked the points, then hit it with the tubing roller, made it into a halo, that has a 1/4 wave tuning stub vs the usual halo gamma match.
things noticed:
1. it was it was no longer "flat " at 144.5, but now flat at 152.300 (ish) with some variation noted when changing the spacing with the loop ends (pretty much like a halo)
2. feed point stayed close to the same spot
3. horizontal orientation was omnidirectional ( no noticible signal strength change on rotation )
4. when oriented vertically and turned it was directional, I assume perpendicular to the loop.
Unlike a halo (a dipole center fed with a gamma) this one turned out to be essentially a 3/4 wave end fed loop (i guess) with a 1/4 wave stub.
That said, I have no idea what the pattern or effectiveness would be horizontal or vertical. tried google to see if there was anybody else that tried this design, see what they thought.....worthless.
all i got was stinking J-pole/slim Jim links, and ads trying to sell me loop or j-pole antennas, the further down i went the more off topic it became....google sucks :-(
next time I build one Ill make it about 15% longer +/- to account for the resonance shift, go from there. Dave Kc5uta