Basically, it's a slim jim j-pole. They won't light the world on fire, but work well for what they are.
You can't beat a flexible roll-up stuff it in a bag antenna for VHF/UHF when you have absolutely nothing else. And yes, I was stuck in a storm with no power and no access to an outside antenna when I strung up a similar antenna for 2M and was able to communicate to the outside world on simplex. It shouldn't be your primary antenna, but it is magic when you have nothing else.
Great slim Jim antenna . One thing , Your SWR will change some in the PVC pipe , most people miss this point . It must be in the clear for proper SWR . Joe @ N9TAX.com Has much info on his home web page . Check it out . He sells them on his web 2wayelectronix.com .
I have used these for years, both in and out of pvc. I used to hang them with a paper clip and a bit of string from the suspended ceiling in my windowless, reinforced concrete and steel first floor office. They were wonderful.
Not sure where the Slim Jim comments come from. I think if you look closely at the top end you will discover that it's not bridged across and therefore not a Slim Jim. The isolated segment on the side above the notch has no functional electrical purpose. I built this one a couple of years ago and added a couple of ferrite beads on the coax at the feed point. I hung it in the clear between trusses in the attic and it's been working a charm ever since. Even with a few feet of snow on the roof (plywood and asphalt shingles) , hitting the local repeater or working simplex line of site around town has never been an issue, even low power on the old IC-O2AT. This antenna is well worth the small effort and nil cost it takes to build.... it's a keeper.
I have a Professor Ed Fong model in the schedule 40 PVC pipe he specifies. Very surprisingly good SWR metrics when placed by a PVC T-Connector to my painters pole.
On his website he states Class 200 pvc pipe not schedule 40 pvc pipe.the schedule 40 pvc pipe wall are to thick and will cause high swr .......
Thank you! I was writing from memory and had been cutting some 40 PVC. I just checked mine as per Ed’s instructions. It’s 200 PVC. Thanks for helping me not inadvertently spread bad info! 73
The Ed Fong I just bought (DBJ-1) specified 200 PSI 3/4" pvc. He specifically warns against using sched. 40 as the 200 psi gives much better RF performance.
I use an Ed Fong J-Pole; not a copy. He and his grad students use a $40k network analyzer to tune each antenna individually, which no other antenna manufacturer does. I've been to his home. I've seen the network analyzer. He's the real deal, and a really nice fellow. The 200 PVC Ed specifies is only for the J-Poles he sells with the PVC end cap. He also sells a roll-up version, which he tunes for not being stuffed into a PVC pipe. If you have the version with the PVC end cap, you must put it in the 200 PVC pipe for it to be tuned optimally. The PVC affects the tune. Make no mistake, the Ed Fong J-Pole has a very low SWR. Mine measured 1:1 across the 2m band the day I bought it. I forget what it was across the 70cm band (very low, I recall), but I've never tried any commercially manufactured antenna that came close. When I connect my Ed Fong J-Pole on top of a 24' painter's pole to my Elecraft KX3, putting out about 2-1/2 W, I'm heard quite clearly by hams in my community who can't hear me at all when putting out 50W from my car mounted antenna driven by my Yaesu FT-7900. This is on the same frequency at the same location. The bottom line is, if you actually do have a well-tuned antenna, and you're not getting acceptable results, move it. In the case of a 2m/70cm antenna, moving it just a few feet can make a noticeable difference.
