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GRA-7350TC Portable Vertical Antenna


Counterpoise

2023-10-30 ​I've been watching the growing use of screens and faraday cloth's as ground plains for vertical antennas with curiosity. I've pretty much settled on four ten foot radials for my vertical POTA antennas whether it be a WRC or other 17' vertical or shorter ones such as the 102" GABIL GRA 7350TC type. They always perform for me and I like the relatively small footprint. But the screen's and cloth type seemed interesting. So I bought off Amazon a 44"x36" piece of Faraday cloth for a few bucks to try it out. 

Today I set up my GRA 7350TC in the front yard on the 36x44 sheet of Faraday cloth. Being breezy it was a bit of a chore to keep it from flying away! I simply laid out the cloth on the sidewalk and set the WRC mini tripod on it. I then set the antenna coil as I normally do for 30 meters. My Ziegu x5105 showed a near perfect 1:1 SWR. I then added my 4 radials which had no impact on the SWR.

There were no POTA spots on 30 meters so I switched to 20 meters. After resetting the antenna coil for 20 meters, the cloth again gave me a near 1:1 SWR. I made six POTA contacts with reasonable to good reports. I then switched to 40 meters, again with a near 1:1 SWR and made two more contacts, one POTA, one non-POTA.
​
All contacts were CW @ 5 watts. My conclusion is that the faraday cloth works similarly to my 4 ten foot radials. As to transport and setup, I think there is a place for both. My radials wind into a small package and easily fit into my POTA kit along with my IC705 and a few other goodies. The cloth is a bit bulky for that as is. Perhaps I can get creative with folding it so it will fit into a small plastic bag so it too will fit. One more antenna variation for POTA! K0BXB

Overview

2023-07-06 Antennas, particularly portable antennas have been an interest of mine for quite a while. And since getting involved with POTA Parks On The Air, they have nearly become a passion! Taking off from the work of others I have built a number of wire and a few vertical antennas. When I got interested in pedestrian mobile I built and/or bought several very short verticals suitable for mounting on a backpack logging just under 150 contacts while walking around. For fixed portable operating I've used the widely used Wolf River Coils vertical which, particularly for the price is one of the most versatile and high performing portable verticals around. taking off that I've build a wire 17' vertical with tapped coil for 40, 30. 20. 15 and above using links in the radiator. And seeking for a smaller, more portable option I built a 9' vertical using a folding military style whip and DIY tapped loading coil. All work well as my log shows.
So why this fairly expensive 7' vertical made in Taiwan? The number one thing that caught my attention is its broken down pack size, just under 12 inches. The second thing, its all HF band coverage. Now that I've had it a while that all-band feature is even more attractive because of the way it achieves that. Most other portable antennas accomplish that with a tapped coil. This one, similar to mobile screwdriver type antennas does it with a sleeve that moves up and down on the loading coil. An added user feature is an etched scale in centimeters so you can record and quickly find a precise location. So I've made a little sticker that for mine which records the position for all the bands I use.
I have two ground mounting options. 1) A Wolf River Coils mini tripod. 2) a DIY 12" aluminum ground spike sharpened on one end and with 3/8-25 threads on the other end with a 3/8-24 coupler. I had to make an adaptor between the ground spike and the antenna with a coax connector. I use four ten-ft ground radials with good success.
As of this writing I've done four activations for a total of 51 contacts on 40, 30, 20 and 17 meters. I've had the antenna about two weeks. I feel like it's on-air performance rivals my other verticals, probably a bit but not dramatically less than the 17' WRC vertical.
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