Swiss Army Knife Antenna

[bwhite]

I listen to a variety of bands VHF Lo & Hi along with 800's in the car.
I have found an old CB mag mount with the coil in the base to reel in an "acceptable" signal across the board. Unfortunately after many years the magnet and the outer-shell of the base have rusted and separated necessitating replacement of my "ol' friend".
Purely by luck I just came into possession of an Antenna Specialists mag mount with base coil marked, I believe 30-36 Mhz. The whip portion appears to be 4 to 4.5' long and fairly crooked. I'd like to hack some of the whip off but not to the point where the change will create undue reception difficulties. Any thoughts on how long the whip needs to remain so that I can still retain "all around" acceptable coverage of the various bands?
I know this sounds a bit vague, my apologies, and for the purists that want "the perfect antenna" that would be great but I'm not able to pursue that at this point.
Thanx all.

 

[ka3jjz]

The base coil almost guarantees that the performance of the antenna - with or without changing the length of the antenna - will diminish as the frequency increases. You could, I suppose, get a couple of mhz wider response out of it, but I seriously doubt anything more.

You would likely be much better off with a good multi band mobile, rather than trying to hack more response out of this Antenna Specialists job, especially if that coil is indeed tuned for the low end of VHF low. Keep in mind that even the best multi band antennas can't 'cover it all' - there are going to be weak spots in the coverage, and it's up to the user to decide what is acceptable. One such weak spot is almost always the VHF lo band, where many mobile antennas are just too physically short to be very resonant without tricks like loading coils. However with more MSP barracks getting tied to a county's trunk system, to me that's not much of a knock. And SHA mobiles become easy to hear when you are nearby - that's a plus when wondering about traffic tieups.

In short, you do your research, it will pay off in the long run 73 Mike

 

[bwhite]

I miss the good ol days when everything was on one band and you could tune you stick.
Yeah, I realize that there is no real good solution to multiband monitoring, that's why on a whim I tried the CB antenna. I'll probably start with this thing full length and nibble it down a little at a time. In the meantime I will keep an eye out for a "real" antenna.

 

[ka3jjz]

Here are a few places - just a few - to read up on reviews of mobile antennas, from our wiki...

‎eHam.net Reviews - Antennas: VHF/UHF+ Omnidirectional (verticals, etc)

Mobile Antenna Comparison - Intercept

Strong Signals - Niljon SUPER-M Mobile Review

MT What's New

I've heard as many bad reviews as good on the NilJon, but it's worth at least a look. Don't ignore the EHam link - even though most of the listed antennas are ham-related, it's worth noting that at least some may be rather broadbanded...73 Mike

 

[bwhite]

That's what I get for reading quickly, I thought it was Nikon instead of NilJon; talk about diversification.....