Newb questions about GMRS roof antenna

[Citizen]

Newb questions, but here goes...

 

I am new to GMRS, but have my license (WRHV686), two Midland MXT105s (one base station, one in my truck), and various hand-held units.  In my quest for a better base antenna, I know I need more height than what’s available indoors in my house with the mag-mount sitting on a cookie sheet.  So I started looking at the roof of my house. 

 

It turns out, we have an old (insert major-brand-name-here) parabolic dish satellite TV antenna that is not being used, as we have been through numerous cable/satellite companies, and  when our contract expires and we go with another company, the old companies just leaves the old dishes behind on the our roof.  Lucky for me.

 

Question-1:

When looking for a place to mount a GMRS roof antenna, it occurred to me that I could use the frame-structure of the old dish on my roof as a mount for a GMRS antenna (see photo).  I would easily remove the receiver arm portion (just a few bolts), but leave the parabolic reflector on the structure, but then rotate it so that is sits completely horizontal.  Once done, it seems the actual parabolic dish (about 24” in diameter and made of metal, I tested it with a magnet), could possibly be used as a ground-plane for a mag-mount instead of a cookie sheet.  Is that right? 

 

Question-2:

Assuming the above is true, would there be any ill-effect because the ground-plane would be slightly parabolic rather than completely flat like a cookie sheet?

 

Thanks in advance for any advice on this.  Love myGMRS.com, wish I had found it sooner.

 

...

 

[WRAK968]

In theory it should work. The dish would simply act as one leg of the antenna much like the cookie sheet. However you may need to extend the feedline to get your mag mount up there which could reduce signal quality depending on how you do it.

Personally, I use 5/8 over 5/8 antennas as they do not require much of a ground plane. By purchasing a base 5/8 over 5/8 antenna and a good feedline you could scrap the dish and just use the 1.5" pole to mount the antenna to.

Either way, I believe you will see an increase in range. I liken it to running a portable from inside of a car vs using an external antenna. Either way you'll have improvement.

[axorlov]

Totally, steel parabolic dish could be used as a ground plane, if rotated horizontally.

There is another option too. Discussed is 2m antenna, but 65cm antenna is even easier to build using this technique:

http://w6nbc.com/articles/2016-03QSTdishslot.pdf

[mbrun]

You may wish to check out one of Ed Fong’s outdoor GMRS antennas. You could remove the dish and mount this to the existing dish pipe. Ed is a professor of RF technologies at a california university and holds the patent for this design.

 

https://edsantennas.weebly.com

 

I own two of the roll-up version of this antenna and they work quite well.

 

You could also make you own. A couple of weeks ago I built my first 1/4 wave ground plane antenna and performance was very respectable. Here is a link to a video of one similar to what I made.

 

 

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