Best Vertical Antenna For Portable Operation...DIY POTA ANTENNA

The efficiency of a 1/4 wave vertical antenna can be greatly improved by getting it up off of the ground. This "do it yourself" antenna covers 20M thru 6M. The lower frequency bands can be covered by adding a loading coil at the base. This antenna is easy to set up and does not require wires or tripods on the ground. A parts list is included in the video.

[@izzzzzz6]

Very good info. Some may want to add some thin plastic between the foil and the paintwork to increase slightly the thickness of the dielectric.
One question. If I have a dipole around 73ohms in impedance and I wish to match it down to 35 ohms into coax. What ratio balun should I make? A 2:1 should be good?

[@Jimscoolstuff]

You will have a fairly good match using 50 ohm or 75 ohm coax. Many hams use a current balun (1:1) to prevent radiation from the coax. Thanks for your comment.

[@dandypoint]

Excellent. Everyone seems to think they want minimum SWR with a quarter wave vertical! My trick on 160 meters is to make my inverted L (top loaded vertical) longer than 1/4 wave to get the R up higher then cancel the resulting inductive reactance with a Capacitor. That also gets the current peak higher on the vertical. Have you thought about how you could top or center load your system? I am using Hustler resonators. I also use the Hustler quick disconnect so I don’t have to screw the mast on each time.
73, de N4DJ

[@DentonBramwellM]

Just figuring out my own POTA setup... found some good ideas in your video. Thanks for posting.

[@Jimscoolstuff]

Thanks for your comment. 73

[@DK5ONV]

💯Nice Video. 👍 Southwest Germany is waving a Hand. 🙋‍♂ 73 de Uncle Günter 👌

[@Jimscoolstuff]

Thank you for your nice comment.

[@dandypoint]

Did you calculate or measure what the capacitance value was on your foil/ rooftop capacitor? The reactance in ohms that you ended up with is really what I am wondering about. I am thinking if it was 15 ohms you would get the 1:1 SWR and as it goes down the SWR rises to the theoretical 1.42 at Xc =zero.
If I did my math right Xc of 15 ohms is about 750 pf. So you would need about 1100 pf to get Xc down to 1 ohm. My numbers indicate if you had 12 inch square plate with dielectric K=2 and a spacing of 0.05 inches you would have about 1290 pf. I have no idea of the K value of car paint, but a K value of 2 seems to be conservative. I also think my 0.05 inch thickness is ultra conservative for car paint, but there may be a slight air gap below your plate so it could go either way. Your plate looks to be larger than 12 inches by 12 inches. So I am guessing your C is larger than 1200 pf.

[@Jimscoolstuff]

I used a 2 foot long by 18 inch wide piece of aluminum foil. That is an area of 432 square inches. I did not calculate or measure the capacitance.

[@dandypoint]

@@Jimscoolstuff thanks. That would give a very low reactance at 14 MHz for sure. I may try making some measurements on some of my mag mounts..

[@craigmaxey4334]

Jim, your wisdom is very valuable…I now will strive for a 35 ohm match with similar vehicle setup.

[@Jimscoolstuff]

Thanks for your nice comment.
73,de KQ8E

[@johndavidson1010]

Thanks Jim. I was thinking of using your idea in this way…. Make the foil patch and magnet to roof of my car but attach the wire to the SO259 to my antenna base mounted on a tripod. This will stop the need for wire counter poises and utilize the car body. ( no roof rack available) What do you think?

[@traveller-nl]

Finally!! Jim, thanks for talking some sense into... oops, I mean about vertical POTA antennas. I love your coupling solution. Myself, I just braid-bonded it to the truck.
Thanks for pointing out the 3/4 wave option and its higher radiation angles. Forgot all about it when operating the long skip on 20m. KX4UI

[@Jimscoolstuff]

Thank you for your comment.

[@KC3UVF]

I love the idea of this mount! I've got a 10m rig in the vehicle and I've been thinking of swapping it out for one of my DX70's. I've been trying to figure out a mounting system for stationary operation that doesn't require me carrying around my pota antenna all the time. I've got a spare 17ft whip and a sunroof. Jackpot!

[@Jimscoolstuff]

Thanks for your comment.

[@mikeramsey9747]

Very informative

[@Jimscoolstuff]

Thanks for your comment.

[@randallstone2444]

…and key ‘til you feel better! Love it, thanks Jim. -Randall, K6RCS

[@Jimscoolstuff]

Thanks for your comment.

[@johnpeterson7264]

Great video !

[@off-trailseeking3965]

Thanks for a great explanation on an elevated 1/4 wave for POTA!

[@Jimscoolstuff]

Thanks for your comments.

[@evertwenderpirt6328]

10 out of 10, Jim. 73 de ZS6AQW

[@Jimscoolstuff]

Thanks for the nice comment.

[@JohnHill-qo3hb]

Very clever Jim, thanks for sharing de ve7kkq

[@Jimscoolstuff]

Thanks for your comment. 73