Mag Mount vs. wire

[Moose]

Living in an apartment I cannot mount an antenna on the roof. What I have been using is a wire that I bought from Radio Shack which mounts on the outside of the window using suction cups. Since I live in a metro area, this has been adequate for me to hear all the locals.
I just bought an MM26ANT from Scanner World, which is an all-band mobile magnetic mount antenna. I attached a wide metal bracket to the outside window frame(wood), on which I placed the mag mount.
As it turns out, the older wire antenna works better than the mag mount. I'm not sure
at this point if the antenna is badly designed or maybe because the antenna is not mounted on a car body. Any insights would be helpful.


Moose

 

[rbhtxk]

Ground Plane

Moose,
I ain't no radio frequency engineer (well I almost am- just never took the test). I looked up the antenna MM26ANT. It needs a ground plane to function properly, or a reflective car body to work against. I have lived in apartments a good part of my life and used mag mounts when I had them. A large pizza pan from Wal Mart works wonderfully for an ad hoc ground plane (up to a point) and even a sheet of aluminum foil in a pinch- sit the mag mount in the middle of the pan. If you’re looking for low band signals (VHF 30-50 MHz), you would do better indoors with about a 6 foot piece of wire hooked into the center pin of the radio antenna connector. Anything higher in frequency should be handled fairly well with the MM26ANT. One other issue, make darn sure that your connections to the scanner are solid. If you are using a bunch of adapters between the antenna and the radio then you are introducing lots of loss and this will cause you problems up around 800 MHz and above.

There's no magic to antennas, any hunk of metal will grab some signals. You have to make sure that those signals get into the radio. And if you get too much signal, you will cause desense or overloading and it'll seem like the antenna is not working good, when it is really grabbing too much for the radio to handle.

You gotta find that happy medium and that is different for every scanner model and physical location (your relative position to the radio transmitting antennas you’re looking to hear). Use what works for you, there's nothing wrong with that wire you mentioned. Good luck!

 

[Pain]

What about creating an artificial ground plane around the base of the antenna with radials? You could make radials by drilling holes in the base and inserting a stiff wire or coat hanger into it. Since the antenna is 26" then you ideally want at least 4 radials of 26"

http://www.bencher.com/pdfs/00361ZZV.pdf

 

[N1BHH]

You really need a solid ground plane under that antenna. You will find the two antennas may have good qualities on different frequencies. One will be better on VHF and the other better on UHF. There are way too many variables to explain, but that's the way it goes. I have had good results from a simple wire hanging out the window.

 

[Moose]

Thanks everyone

I've ordered another companies magnetic mount antenna just to see if there is any difference in the reception as things are set up now. What I plan to do after the simple test is to install my window mount air conditioner and mount the antenna on top of that to see if it will act as a ground plane. I like the radial idea but that would make the antenna more visible. As it is now, it hugs the window frame and is not too conspicuous.

Do any of you guys know if running a ground wire to the bracket would suffice for a
"ground plane"? Just wondering. Thanks again.


Moose

 

[Don_Burke]

Do any of you guys know if running a ground wire to the bracket would suffice for a "ground plane"? Just wondering. Thanks again.

Probably not. Several wires would do better and they can be pretty fine and still work.

 

[lowboy654]

For a mag mount I use this and it works great for 800mhz and good on VHF sometimes I put it on a lamp in my house and can get 800MHZ from 35 miles out.
http://www.rffun.com/catalog/scanants/1190.html