State Patrol Radio

I have a State Patrol car and I am baffled as to how many antennas this car has and with out going out in the rain there are two on the trunk (holes) and I believe 5 on the roof so my question is why so many radios also with the antennas so close together doesn't this cause a bad SWR?
JimG

Guessing here...
800 transmit
800 receive
VHF (not sure if those have separate rx and tx antennas)
Mobile data transmit (pre lte)
Mobile data receive
GPS
UHF (In some areas)

That's 7-8 accounted for...

I'm sure there is interference, but what are you going to do? Limited real estate and mission needs must meet somewhere


Sent from my iPhone using Tapatalk

Adding a few more possibilities: Scanner, CB radio and dash camera microphone receive antenna.

If it's an older car, one coming from an area that was last to migrate to ARMER, you'll have the old VHF set-up in addition to the ARMER radio. That would be one antenna for the main vehicle radio and then another for the vehicular repeater (portable radio carried by the trooper).

Also, somewhat mentioned above, in rural areas some troopers may have local law enforcement radios installed (Pre-ARMER).

As noted above, there could be antennae used for mobile data before the air cards came around. In such cases they usually used either two or four.

this car is a 2006 I did not know you need a seperate antenna to tx and rx learn something everyday

There's probably a little confusion at work in how a post was phrased. You are right, typically radios only use one antenna that both receives and transmits.

Old statewide radio systems involving state law enforcement entities used a mobile vehicular repeater system. Troopers would carry a portable radio to remain in communication, but the range of portables is very limited. So there would be a device in the police car that received transmissions from the portable and "fed" them into the mobile radio in the car, which would then pass the "boosted" signal to the receiving tower.

Portables would be on one band, such as UHF. The mobile radio in the vehicle would be on VHF. So two antennas were needed. One for the mobile radio in the vehicle and another to communicate with the portable carried by the trooper.

Other terms for these in car repeaters are Pac RT (Moto) or Vehicle Extender.

Depending on where your 2006 was assigned, it is quite likely it used this type of system.

A while back in the Wisconsin forum, there was a picture posted of a WSP vehicle describing all the antennas it had (noting you have MSP but the concepts are similar)

Something of possible interest is the page below on the California Highway Patrol radio system. Down the page is a picture of all the antennas and their use.

CALIFORNIA HIGHWAY PATROL MOBILE RADIO EQUIPMENT 2001

wisconsinjimmy said:

I have a State Patrol car and I am baffled as to how many antennas this car has and with out going out in the rain there are two on the trunk (holes) and I believe 5 on the roof so my question is why so many radios also with the antennas so close together doesn't this cause a bad SWR?
JimG

Click to expand...

Did you buy the car from the Wisconsin Surplus site? I check the surplus vehicles every once in a while. But most of the cars are high mileage and well worn. I always wondered about the "certified speedometer" placarded on the dash of these "police cars" really meant...

For anyone who is interested:
http://www.wisconsinsurplus.com/

Every once in awhile there are VHF/ UHF mobile radios listed there also. Lots of boats, snowplows, lawnmowers, and utility vehicles.

Don't forget a cellular antenna as well.

Chief

mmtstc said:

Guessing here...
800 transmit
800 receive
VHF (not sure if those have separate rx and tx antennas)
Mobile data transmit (pre lte)
Mobile data receive
GPS
UHF (In some areas)

That's 7-8 accounted for...

I'm sure there is interference, but what are you going to do? Limited real estate and mission needs must meet somewhere


Sent from my iPhone using Tapatalk

Click to expand...

Every 800MHz mobile radio I have ever seen does not have separate TX and RX antennas. Same with mobile data terminals.

Probably:

800MHz
UHF
VHF WISCOM
VHF interop
Cellular
GPS
Silent Witness wireless mic antenna
Mobile extender

3 closely spaced antennas in a triangle (generally on the roof) will be for tracking the loot bag from a bank robbery. They are closely spaced and in a specific pattern to allow the Doppler tracking system work. On the officer's car, these are receive only.

4 closely spaced antennas in a square (generally on the roof) will be for the LoJack stolen car tracking system. Similar to the bank tracking system they're closely spaced and in a specific pattern to allow the Doppler tracking system to work. On the officer's car, these are receive only.

Most often a single antenna is used for both transmit and receive so you should only have a single antenna per radio. There will be multiple radios per vehicle though. Often there's one for the main car radio, one for the car's computer, and perhaps one or more additional radios for communicating with other agencies. Often they'll have an additional antenna for the main radio's vehicle repeater that allows the officer to use their handheld radio to talk through their main radio to improve handheld radio communications when out of the car.

There may be additional radios for auxiliary use such as GPS, a wireless microphone to provide audio to the dash cam's video, and a few other specialized tasks.