OEM Antenna cluster

[TongSlinger]

I have 3 uniden scanners sitting on top of each other. since they are stacked, the factory collapsible antennas are in very close proximity. Does this degrade reception? I don't need an external antenna to receive the channels I'm listening to. What is the receive patterns when the 3 antennas a aligned very close in a row. I'm trying to keep them as vertical as I can. What would be the best placement of the three antennas in this case

Thanks

 

[krokus]

A lot of complex modeling for that answer.

Hooking up one antenna to an antenna distribution, which feeds the scanners, would be more predictable.

 

[Ubbe]

I don't need an external antenna to receive the channels I'm listening to.

When using antennas inside a room the RF signals will bounce around and just moving an antenna a couple of inches could change reception a lot. Any metal close to an antenna will interfere. If one scanner receives the systems with the weakest signals then have that vertical and the others pointing away from it. The length of a telescope antenna are also important, if you any of those, so try different lengths to receive the weakest system a bit better.

/Ubbe

 

[TongSlinger]

I didn't realize that indoor confined placement would have such an impact with relative close stations. I did a simple re-alignment of the antenna and it changed reception dramatically. P25 p1 stations that were only receivable on one scanner are now receiving on all 3 scanners at a high signal strength. 0 bars and static to crystal clear with 5 bars. The scanners are SDS200, BCD996XT and BCD996P2.

Thanks for the assist!

 

[merlin]

For receiving, the proximity of antennas is really insignificant especially being less than 1/4 wave apart.
The overall location can affect performance like moving a couple feet. You have dead spots because of reflections and when they are out of phase, you get nothing. On the other hand, reflections in phase improve the field.

 

[a417]

Does this degrade reception?

I don't need an external antenna to receive the channels I'm listening to.

If it ain't broke...

 

[E_Tek]

I have also wondered about this too, whether it is bad for the receivers or affects reception in any way to have multiple RX only antennas in such close proximity to each other. Sometimes on my bench, i'll have my main base scanner, a handheld scanner and 3 shortwave radios all going at the same time with their stock antennas fully extended and within 5-6 inches apart from each other.

 

[TongSlinger]

I have been experimenting with the placement of the three antennas setup. It has made a big difference in station reception. Ii didn't realize I could create dead spots by accident. I was always curious why the 3 scanners couldn't receive the same stations at the same time. Obviously, its in the antenna placement within the cluster. I thought the signal washed across the antennas like a wave washes across a spot on a beach. Absorbtion and deflection must pay a part in each antennas ability to receive the same signal.