2 Meter Antenna for Mobile Scanning

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radiowave15

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I like symmetry. But I also like to get solid signals into transmitters and receivers. But here's my question. I have a 2 meter rig in the car and on the driver's side trunk I have a 1/4 wave lip mount antenna for it. Works great and hits all of the repeaters that I want to hit.

I have a portable scanner for the car now and want an antenna for that as well.

So, since I would really like the look of a matched set of trunk mount antennas, is it a bad idea to just put another 2 meter antenna just like my current one on the other side? How much of a drop off would a 144/440 Mhz antenna give versus a true mobile scanner antenna? Most of the police and fire/EMS that I would like to listen to are in the 800 Mhz area.

Thanks,
Dan
 

KJ6HCB

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Obviously, having an antenna tuned for the 100 and 400 Mhz band will not function will in the 800 mhz band. Since you arent TXing, not as big of an issue, but you wont be drawing in distant signals.

Ill also mention that you say you have a 1/4 wave antenna on a lipmount... no bueno. 1/4 waves require ground planes - like the center of a roof. If you are mounting a lip mount antenna I would recommend some sort of 1/2 wave no ground plane antenna.
 

radiowave15

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KJ6HCB, thanks for the reply. True, this 2 mtr antenna has very little gain but I have been surprised at how well it has performed. The rig will put out 5, 25, or 50 watts and using 5 or 25 I can hit repeaters 30 to 50 miles away. I'm sure a 1/2 wave would do much better but I really like the low profile of this one.

Thanks again.

Dan
 

n5ims

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You could keep the quarter wave for 2 and for the other side get the Larsen tri-band 150-450-800 antenna (Larsen NMO150/450/800 Tri-Band NMO Antenna) for your scanner. While they both won't look identical (the tri-band has a mid-whip coil), they'd both be about 19" tall.

Please note that the provided link was just one of the first that popped up with a Google search on that antenna and not a recommendation on where to get it. The link was only to show you which antenna I'm talking about.
 

prcguy

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The 1/4 wave 2m antenna will work fine for much of the VHF commercial band and will also work OK in the UHF amateur and commercial band but not so good at 800MHz.

The trunk lip mount is also fine and there is plenty of ground plane provided by that style mount.

I also agree you could swap the 2m 1/4 wave for a tri-band Larsen and gain better performance at 800 while giving up just a little on 2m.
prcguy




Obviously, having an antenna tuned for the 100 and 400 Mhz band will not function will in the 800 mhz band. Since you arent TXing, not as big of an issue, but you wont be drawing in distant signals.

Ill also mention that you say you have a 1/4 wave antenna on a lipmount... no bueno. 1/4 waves require ground planes - like the center of a roof. If you are mounting a lip mount antenna I would recommend some sort of 1/2 wave no ground plane antenna.
 
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W2NJS

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My personal experience with "using a single-band antenna on another band" has been with a Comtelco UHF puck For VHF receive it works, but it's usually quote noisy. Also, it gives NO RSS indication on an Icom 208 when receiving VHF, although the signal is, as I said, quite noisy. I haven't tried the antenna on 800. Put another way, there's no free lunch when it comes to this question, and you're probably going to have to "give" on your desire for antenna symmetry. And you might also consider drilling holes in your trunk lid to improve the omnidirectional capability of any antenna on the car.
 
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n5ims

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The 1/4 wave 2m antenna will work fine for much of the VHF commercial band and will also work OK in the UHF amateur and commercial band but not so good at 800MHz.

The trunk lip mount is also fine and there is plenty of ground plane provided by that style mount.

I also agree you could swap the 2m 1/4 wave for a tri-band Larsen and gain better performance at 800 while giving up just a little on 2m.
prcguy
The OP appears to be happy with the performance of their 1/4 wave antenna on their 2 meter ham installation, but is asking about a second antenna to be used for a scanner.

I have a 2 meter rig in the car and on the driver's side trunk I have a 1/4 wave lip mount antenna for it. Works great and hits all of the repeaters that I want to hit. ... So, since I would really like the look of a matched set of trunk mount antennas, is it a bad idea to just put another 2 meter antenna just like my current one on the other side?
One thing that the OP should watch out for is having the two antennas too close together, especially when transmitting with high power since the very strong signal will overload the scanner front end and possibly damage it. Generally the key is distance between the antennas (both vertical and horizontal distance, if possible) and transmitter power (lower power = less damage possibility, more power = higher possibility) and if possible having the scanner off when transmitting (although this may not fully protect all scanners). See the following threads on this issue (search for more since this is only a few of the available threads on this topic):

http://forums.radioreference.com/uniden-scanners/222461-question-about-scanner-rf-damage.html
http://forums.radioreference.com/uniden-scanners/183496-rf-damage-396xt.html
http://forums.radioreference.com/general-scanning-forum/172923-will-transmitting-cb-ham-radio-damage-scanner.html
http://forums.radioreference.com/general-scanning-forum/218178-mobile-scanners-ham-radios-damage.html
http://forums.radioreference.com/uniden-scanners/141883-996-sensitivity-front-end-rf-damage.html
 
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