How close to each other can I mount thru the glass antennas

[fulfordr]

I have a Parrot hands free cellular telephone setup that uses a thru the glass antenna. I recently purchased a Radio Shack multi frequency thru the glass antenna that I plan to use with my BCD996XT scanner. How close to the cellular antenna can I mount the Radio Shack thru the glass antenna. The instructions in the Radio Shack antenna just say to mount it 1 1/2 inch from the edge of the glass. Would there be any intereference from the cellular antenna if I mounted it beside it, 1 1/2 inch away for it and the edge of the glass?

My other option is to go to the other side of the vehicle where a Larsen thru the glass tranciever antenna is mounted that is no longer in use. I had thought of moving the Radio Shack antenna to the outside portion of the Larsen antenna as it will screw onto the mount. Then taking off the inside portion of the Larsen and replacing it with the Radio Shack box with antenna lead that comes with the Radio Shack multi frequency antenna. The Larsen antenna was used on a 450.000 type business radio and I dont know if the inside window portion is loaded for that or not. I dont know if the Radio Shack inside portion is loaded somehow for multi band either. Any info on this would be appreicated. Sorry for the long post...

[ermin]

Originally Posted by fulfordr

I have a Parrot hands free cellular telephone setup that uses a thru the glass antenna. I recently purchased a Radio Shack multi frequency thru the glass antenna that I plan to use with my BCD996XT scanner. How close to the cellular antenna can I mount the Radio Shack thru the glass antenna. The instructions in the Radio Shack antenna just say to mount it 1 1/2 inch from the edge of the glass. Would there be any intereference from the cellular antenna if I mounted it beside it, 1 1/2 inch away for it and the edge of the glass?

My other option is to go to the other side of the vehicle where a Larsen thru the glass tranciever antenna is mounted that is no longer in use. I had thought of moving the Radio Shack antenna to the outside portion of the Larsen antenna as it will screw onto the mount. Then taking off the inside portion of the Larsen and replacing it with the Radio Shack box with antenna lead that comes with the Radio Shack multi frequency antenna. The Larsen antenna was used on a 450.000 type business radio and I dont know if the inside window portion is loaded for that or not. I dont know if the Radio Shack inside portion is loaded somehow for multi band either. Any info on this would be appreicated. Sorry for the long post...

I would never put a scanner antenna near a transmitting antenna. Even tho it is for a cell phone it could still cause problems.

73

Ermin

[LtDoc]

There's no 'always correct' answer for that. It's a fairly good idea to place antennas as far apart as possible/practical. There can always be some interaction between antenna so the idea is to minimize that interaction as much as possible. Distance is a good way of doing that. If that scanner is going to be monitoring frequencies in the same band as the transmitting antenna, then there will be MUCH more interaction, possibly destructive interaction. Distance between antennas in that situation needs to be -much- larger, and will not assure something doesn't get too 'upset' to work anymore.
As far as mixing/matching antenna parts, it's better not to if possible. As you suggested, there can be differences that are not readily apparent, who knows what would result. One aspect of that is that receiving antennas tend not to be 'exact' as those used for transmitting. Receivers are just not as 'picky', sort of.
No matter what bands of use, I honestly don't think antennas within inches of each other is a good idea at all.
- 'Doc

[W2NJS]

You probably should not "mix" parts from two different thru-glass antennas. Use all the parts, inside and outside the glass, from one complete installation kit. The inside tuner box is made for one outside antenna only so you should work with the matched setup.

In your case a probably "safe" separation distance would be 19 inches or so, which is the quarter wavelength for 150 mHz. As always with these kinds of antennas, watch out for defroster wires in the glass.

[fulfordr]

Well, I went by the local radio shop today and had them take off the Larsen antenna and replace it with the Radio Shack model 20-011 multi band thru the glass antenna. Took them about 30 minutes total time and was worth the money spent to have them do the removal and installation. I'm in hopes that the outside Radio Shack mount will stick on as well as the Larsen mount did.

While there, I questioned the tech about mounting the antenna next to the Parot system...Like LtDoc said, it would be a bad idea if I planned on listening to anything in the same band range as the Parot system as it being a transciever, it would cause interference when the phone system was in use. He also looked at the Larsen and the Radio Shack antenna, and said not to mix the parts ,as they were both loaded for different bands and usage.

So far the Radio Shack antenna seems to be picking up alot better than the Larsen which was tuned for 450.000 band.