Mobile Antenna Placement Question

[EMSheriff]

I drive a 2008 Honda Civic Coupe and I will finally be installing a permanent mount antenna for my scanner. I will be installing a laird VHF quarter wave whip with a through hole NMO mount. I have an analog scanner and the majority of what I listen to is VHF.

I will be mounting it on the trunk but there are two potential mounting positions - I have attached a diagram of the two positions for visual reference. Scanner Antenna Position 1 is right in the center of the trunk but installation will be a little more difficult due to there being a structural member for the trunk right below it; leaving a small space for drilling and the coax. Scanner Antenna Position 2 is on the vehicle's centerline, but is placed further forward since would be an easier place to install because there is a hole in the under structure of the trunk. Would one position yield better reception over the other or would the difference between the two positions be negligible for my application?

 

[ra7850]

Keep in mind that depending on the placement the antenna may hit the window when you open the trunk. If it does that repeatedly, it will scratch the glass. I'm not an expert but if it's going to be receive only, not sure it's going to make that much of a difference.

 

[ladn]

Position #1 is probably more ideal. A concern with Position #2 would be that the antenna would hit the window when the trunk opens.

If the "structural member" is hollow (and it probably is), you could drill a hole in it and bring your coax out directly, then use the appropriate cable clamps to secure it to the trunk lid and route it to where it will go under the carpet. I've done this with a few installs and never had an issue. It would be a good idea to protect the cable going through the hole with a grommet,

In theory, Position #1 will yield marginally better performance and less directionality because there will be more ground plane under the antenna, but I doubt you'd notice the difference.

 

[FIRE321FIGHTER1985]

The best place to attach a mobile scanner antenna is the center of the roof.

 

[900mhz]

Position #1 is probably more ideal. A concern with Position #2 would be that the antenna would hit the window when the trunk opens.

If the "structural member" is hollow (and it probably is), you could drill a hole in it and bring your coax out directly, then use the appropriate cable clamps to secure it to the trunk lid and route it to where it will go under the carpet. I've done this with a few installs and never had an issue. It would be a good idea to protect the cable going through the hole with a grommet,

In theory, Position #1 will yield marginally better performance and less directionality because there will be more ground plane under the antenna, but I doubt you'd notice the difference.

position # 1 will also give you a more uniform ground plane as well.

 

[EMSheriff]

Thank you for all of the replies. It sounds like putting the antenna in the center at #1 in the center of the trunk is the way to go.

ladn, the structural part of the trunk under the #1 location is hollow. If you have had success with it, I will try drilling a hole to run the coax out of it and fit a grommet to the hole.

 

[mmckenna]

I've done installs like that before on other cars, and it works fine. Careful routing is key. Route it along the hinge mechanism, and secure it well so it doesn't move around and risk getting pinched. Some split loom over the exposed coax is a good idea, too.

Should be a nice install, will look better than a mag mount.

 

[EMSheriff]

I've done installs like that before on other cars, and it works fine. Careful routing is key. Route it along the hinge mechanism, and secure it well so it doesn't move around and risk getting pinched. Some split loom over the exposed coax is a good idea, too.

Should be a nice install, will look better than a mag mount.

mmckena, that is exactly what I was planning on doing. My trunk hinge has holes pre drilled for cable tie push-mount bases which should make routing it fairly easy. One hinge uses the push-mount bases with cable ties for the trunk harness and I am going to route the coax down the other hinge.

 

[mmckenna]

mmckena, that is exactly what I was planning on doing. My trunk hinge has holes pre drilled for cable tie push-mount bases which should make routing it fairly easy. One hinge uses the push-mount bases with cable ties for the trunk harness and I am going to route the coax down the other hinge.

If you want to get fancy, run a ground strap from the vehicle body to the trunk lid. Not all of them are grounded really well through the hinges/latches.
Probably won't be an issue for a scanner, but it's good practice if you ever decide to transmit.

Amazon.com

 

[EMSheriff]

If you want to get fancy, run a ground strap from the vehicle body to the trunk lid. Not all of them are grounded really well through the hinges/latches.
Probably won't be an issue for a scanner, but it's good practice if you ever decide to transmit.
Amazon.com

Thanks for the tip, I will probably end up doing that.

 

[ra7850]

Thanks for the tip, I will probably end up doing that.

Be sure post photos when you're done.