Car AM/FM Antenna as Scanner Antenna

[TZB3]

I'll start by saying I'm relatively new to antennas.

While trying to decide what kind of antenna set up would be reasonable for my vehicle, I had the idea to patch into my AM/FM radio antenna (the one that came with the vehicle) to use it as a scanner antenna as well. Would a vertically mounted car radio antenna (approximately 33" long) work as a basic scanner antenna for the 150-160mhz and 400-500mhz bands? I would be putting an in-line splitter on the car antenna cable and adapting it down to BNC.

Thanks.

 

[jwt873]

The car antenna will pick up signals. It won't be as good as a dedicated antenna resonant at the frequencies that you want to hear.

They make multicouplers that allow you to use car antennas for scanners. Here's a cheap one. https://www.amazon.com/Dynamics-PDC634MB-SCANNER-ANTENNA-MULTICOUPLER/dp/B00DSB488I (I don't know how well they work. I've never tried one and have never heard any reviews).

 

[bob550]

An antenna of 33 inches in length would be resonant at around 85 MHz, which would not be terribly effective at your frequencies of interest. Then too, the use of a splitter would further degrade the incoming signal. That said, almost any antenna outside your vehicle is better than one mounted inside. If it was easy enough to access the car antenna connector to install a splitter, you could experiment to determine if this setup worked. Keep in mind that the factory antenna connector may be of a type that is specific to your vehicle brand at worst, or perhaps Motorola at best. But, I would not cut the factory antenna connector in any way to make this work. I also would not keep both the car radio and scanner in use at the same time as one may cause interference to the other.

 

[popnokick]

The AM/FM antenna couplers for scanners work better than anything you have inside the vehicle. But as noted in this thread not as well as a purpose-built mobile scanner antenna. Using the existing AM/FM broadcast antenna also offers stealth in appearance and simple installation. Don’t worry about resonance on the receive frequencies.... scanning receivers do pretty well with untuned antennas... that is how manufacturers get away with including short back-of-set antennas with every scanner. Yes, you can do better... but they work for strong signals. And what is the reason you want maximum receiving range in a mobile installation? When I’m mobile I’m interested in road hazards, emergency vehicles, and other radio comms likely to be in my vicinity.... not two counties away.
One drawback is that the AM/FM couplers do reduce the sensitivity of your AM/FM broadcast receiver in the vehicle. But not so much as to make it unusable.

 

[DJ11DLN]

I suggest you try it and see how it works. I did this back in the '80s and '90s with a few different vehicles. All had similar antennas and it varied from working very well to acceptable to horrible. And the ones that worked well seemed to affect broadcast band reception the least. I was using a simple "Y" adapter from RS of the type intended to combine signals from a pair of antennas. Only way to know how yours works is to give it a try.

 

[Ravenkeeper]

I suggest you try it and see how it works. I did this back in the '80s and '90s with a few different vehicles. All had similar antennas and it varied from working very well to acceptable to horrible. And the ones that worked well seemed to affect broadcast band reception the least. I was using a simple "Y" adapter from RS of the type intended to combine signals from a pair of antennas. Only way to know how yours works is to give it a try.

That's the way I have ran mine since 1991. Got in behind the radio, and used a splitter to connect to my scanner. Didn't bother me one bit, never noticed any reception degradation on my stereos, nor my scanner. Ran my scanner this way in my '91 Nissan King Cab, '93 Grand Am, '99 Grand Am, '03 Grand Cherokee, '06 & '10 Ridgeline, '15 Silverado, and (SOON) my '18 Silverado.

 

[jmp883]

Back in the 80's and 90's I also used a splitter between the scanner and the car stereo and also noticed no noticeable loss of radio performance in any of my vehicles. An external scanner antenna is preferred, but this option could work for you.

 

[DJ11DLN]

That's the way I have ran mine since 1991. Got in behind the radio, and used a splitter to connect to my scanner. Didn't bother me one bit, never noticed any reception degradation on my stereos, nor my scanner. Ran my scanner this way in my '91 Nissan King Cab, '93 Grand Am, '99 Grand Am, '03 Grand Cherokee, '06 & '10 Ridgeline, '15 Silverado, and (SOON) my '18 Silverado.

Back when I did it, I was using a BC560xlt. And I would notice a slight degradation of broadcast signals but only when the scanner was on. When I turned it off I couldn't tell the difference between that and the coax going straight into the broadcast radio. Since I almost never tried to listen to both at once it wasn't a problem for me.

I'm tempted to try this with my Terrain but getting to the antenna connection is almost as intimidating to me as dropping the headliner with all the airbags and other stuff up there for a NMO install. I really miss those older vehicles where you could access stuff without too much trouble.

 

[iMONITOR]

I'll start by saying I'm relatively new to antennas.

While trying to decide what kind of antenna set up would be reasonable for my vehicle, I had the idea to patch into my AM/FM radio antenna (the one that came with the vehicle) to use it as a scanner antenna as well. Would a vertically mounted car radio antenna (approximately 33" long) work as a basic scanner antenna for the 150-160mhz and 400-500mhz bands? I would be putting an in-line splitter on the car antenna cable and adapting it down to BNC.

Thanks.

Won't hurt anything to try it. If you're in a reasonably good signal area it will probably work fine.

 

[Ravenkeeper]

Back when I did it, I was using a BC560xlt. And I would notice a slight degradation of broadcast signals but only when the scanner was on. When I turned it off I couldn't tell the difference between that and the coax going straight into the broadcast radio. Since I almost never tried to listen to both at once it wasn't a problem for me.

I'm tempted to try this with my Terrain but getting to the antenna connection is almost as intimidating to me as dropping the headliner with all the airbags and other stuff up there for a NMO install. I really miss those older vehicles where you could access stuff without too much trouble.

For me, I just have to open up the forward portion of the top of my dash. BUT, I have to find a 12'+/- coax to go from the junction, across the dash to the left post, down to the bottom side of the dash, back across to the center console, and to my scanner.

 

[Mike445]

I've been running my BCD996T like this in my 95 Z28 for many many years. No issues at all. It works great on VHF and decent on UHF. It's decent on 800mhz as well. It picks up everything in my county and surrounding areas. I'm using an old antenna splitter that turns my car antenna cable into both a car antenna and scanner antenna with BNC. It's not nearly as good as my NMO mounted Larsen tribute band on my Charger but it works well enough. Good luck!
Mike

 

[majoco]

Some more modern vehicles have the antenna buried in the rear screen or a very small stubby - with an amplifier close to the antenna base. The amplifier is fed power from the radio so breaking into the coax may not be such a good idea without some special isolator to let the power through but to stop it from getting in to your scanner. I would imagine the amplifier has frequency responses to suit the AM and FM BC bands only too so you may be completely out of luck.

 

[KF4JYE]

Many years ago, I used a similar antenna splitter on my 1985 Nissan truck. It worked okay on VHF, but poor on UHF, with the stock 30" AM/FM antenna. So, I replaced the stock antenna with a Radio Shack scanner antenna (item #20-032) which fit perfectly into the stock antenna mount. This worked great for VHF and UHF on my scanner, and just as good for the AM/FM radio as the stock antenna. The Radio Shack antenna came with a magnetic mount which was attached with a set-screw. Fortunately, the lower rod of this antenna was the same size as the stock antenna rod which was also fastened with a similar set-screw arrangement. If you can still find one of these Radio Shack antennas, it may work for you also.

 

[Kfred]

got a new chevy pickup man years ago , ordered stock antenna kit from dealer. installed it on opposite side in same location as original am/fm antenna, used adapter to match scanner. pickup had 2 radio antennas. worked pretty good on vhf high. most people never noticed it.

 

[iMONITOR]

got a new chevy pickup man years ago , ordered stock antenna kit from dealer. installed it on opposite side in same location as original am/fm antenna, used adapter to match scanner. pickup had 2 radio antennas. worked pretty good on vhf high. most people never noticed it.

Yes make it as invisible as possible! I live in a nice area but anything that stands out is a magnet for smash & grab! I remember when it was cool to put all kinds of antennas on your vehicle, special fog/running lights, special effects, and yes even some stickers bragging about your hobbies, special interest, politics, etc. Now any of that is just drawing unwanted attention and trouble. NRA stickers are one of the worst!

If you have a dark vehicle and use a black antenna, I think that's the best!

 

[DJ11DLN]

Yes make it as invisible as possible! I live in a nice area but anything that stands out is a magnet for smash & grab! I remember when it was cool to put all kinds of antennas on your vehicle, special fog/running lights, special effects, and yes even some stickers bragging about your hobbies, special interest, politics, etc. Now any of that is just drawing unwanted attention and trouble. NRA stickers are one of the worst!

If you have a dark vehicle and use a black antenna, I think that's the best!

I'm "blessed" with two black vehicles; buying used or even new in late fall to get discounts for old/new models, you take what you can get. The pickup has an NMO which is black as well as the whip, even sticking up out of the middle of the roof it all but disappears. The Spectrum Force stuck to the Terrain also is barely noticeable, the luggage rails help with that a great deal. I try very hard to stay off of everyone's radar with my vehicles.