Antennas: A Different Twist on a Dual-Band VHF/UHF J-Pole
https://batteryeliminatorstore.com/blogs/ocf-masters-blog/antennas-a-different-twist-on-a-dual-band-vhf-uhf-j-pole
J-poles suck.
You NEVER see one in commercial use either. MUCH easier to make a sloping-radial ground plane antenna with wire soldered to a BNC or SO-239 socket AND it has a much cleaner pattern too.
Components and transmission line have changed a lot since 1900.
A lot of the early day antenna design is still very functional. As far as my logic, simple works. Simple is a technique the is avoided at all cost today.
Complexity is destroying us and making us slaves to systems we did not want or design.
Freedom is being killed by unnecessary complexity and along with it good design.
I used a Jpole this evening.
I guess I will have to go back to the net and tell them it doesn’t work.
No idea what a j pole is but I listen to am radio and the reception is worse now than it ever was. How to I get better reception? Once I’m within a mile of this fire station it is all static and high pitch noises.
I’m moving into a new house soon...it’s a great Ham location, on a hilltop, horizon in view in all directions.
I’m going to put up a J-Pole made from 450 ohm ladder-line.
The J-Pole is an old design that works.
It was first used slung beneath German Zeppelins in WW1.
Another, more recent half-wave end-fed design uses an rf transformer to match a high-impedance end-fed walf-wave wire to the 50 ohm input that most rigs have.
They are simple to make using a toroid such as the ft240-43.
The bottom 1/4 wave section of a J-Pole is the matching transformer... at the very bottom you have 0 ohms and at the top you have 2000+ ohms... you just find the 50ohm spot near the bottom and connect the 50ohm coax at that point...this is about as simple an antenna design as you will ever find.
It’s a bit disconcerting to some though as it sure looks like a dead short across the coax...and it IS a dead short if you consider only DC but at rf frequency AC it is NOT a short it’s just a transformer.
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