I have built a few j-pole antennas for 2 meters and 70 cm over the years and they have worked very well. Being made of copper pipe they are heavier than commercial aluminum antennas but they work. ............................ The J-pole antenna, also called the Zepp' antenna (short for Zeppelin), was first invented by the Germans for use in their lighter-than-air balloons.[1] Trailed behind the airship, it consisted of a single element, one half wavelength long radiator with a quarter wave parallel feedline tuning stub. This was modified into the J-pole configuration by at least 1936[2] with continuing refinements by 1943[3] and became popular with amateur radio operators because it is effective and relatively simple to build. General information and calculator. J Pole Antenna Handbook Home Page On line calculator J POLE ANTENNA DESIGN CALCULATOR by K4ABT
I was planning to make one for the house after I get my license. Any reason to use 3/4" pipe over 1/2"? Seemed like a marketing ploy to me. Whynot
Stability, I would think. I'd like to see a thread on how to build antennas. (A build along type). Personally, I'm not that interested in the theory, nor do I want to waste time and material feeling my way through the process. I'd like clear, simple, assembly instructions.
A larger diameter element will have a broader bandwidth...but may not be enough to notice at those freqs.
In the Comms Forum, I posted a J Pole made from electrical Conduit parts, for 10 Meters... If you take those dimensions and scale them up or down, you can design an Antenna, for any Band. A few years back, I saw a really cute VHF/UHF Dual Band J Pole, that worked well....
You can build a J pole out of any conductive material. There are cook book solutions available on the web. I know of no multi band J.
I think it's a two-meter J-pole operated on it's third harmonic, in the same way that a 40-meter dipole can be used on 15 meters. William Warren
a J-pole built for 2 meters is close enough to work well on 70cm. I built a copy of the Arrow OSJ and it was great on both. They also have plans for a dual band version but I wouldn't bother. I also built a 2m "slim jim" from 450Ω window line, also worked great. My mom had a "plumber's special" on her roof for years before weather bent it over, worked great too. Take the time to get the match right at the start and they work great. If you choose to know nothing about adjusting matches, then the aluminum rod Open Stub J (OSJ) doesn't require any adjustment, only measuring inches.
I had a Novice ticket back in the 60's, and we could use voice on two meters. I had a Heathkit Two'er that I loved, regenerative receiver and crystal control too. I used a two-element beam and I loved mountaintopping - so long as the mountaintop had a spare AC outlet (or a way to strap one on). When I got the tech, I bought a used Radio Shack six meter rig, and made a "Plumber's Delight" five-element beam that I had up on my roof - excuse me, my dad's roof - for seven months before a snowstorm proved stronger than the nails. I learned a lot, mostly about tuned stub filters to cure the incredible TVI the RS rig put out. Ah, the good old days.
