Antenna mounting - power v. height

[diabetiktaco]

I have a 6dB gain GMRS antenna mounted on my front bumper so it sits low. I wasn't getting any range in the woods today. I ordered the 3dB gain ghost antenna to mount on the roof rack. Would a 3dB antenna get better range mounted high than a 6dB mounted low?

 

[Sparksalot]

Yes. The body is blocking the signal to and from the antenna down on the bumper.

 

[OTH Overland]

I have found antenna location plays a bigger role than gain, for a circular radiation pattern, center of roof should be the best spot. Most antennas use the vehicle sheet metal for a ground plane, centered will give best all around pattern, front bumper will distort the pattern and push it to the rear opposite corner. anything metal higher than the mounting point can affect the pattern also. Using a SWR meter and tuning the antenna length for as close to a 1:1 match can improve reception quite a bit. Make sure you are using one of the channels that allows for high power 1-7 have a 5 watt limit, 8-14 have 0.5 watt, 15 & up have 50 watts, most mobile radios will lower their power on the lower channels automatically.

 

[Downs]

Don't focus on gain too much. In many instance for what we do where we're in varied terrain the higher gain antennas can be detrimental to our use. THe higher the gain the more the signal is "pinched". It projects the signal more towards the horizon vs something like a unity gain or 3db gain antenna that tends to make a dome or donut shaped radiation pattern that's better at getting around terrain many times.

Here's a graphic to help visualize it.

I personally carry more than one antenna with me. I carry a high gain for the flat lands which I keep on most times because of where I live. But when I get into the woods and varied terrain I swap on a 6 inch lower gain antenna that not only doesn't get snagged on every tree branch around but also tends to give me better performance over varied terrain.

 

[Sparksalot]

@Downs has a good point about gain. The little bitty stub on the roof line directly above the rear wheel is my GMRS antenna. Going between hilltops I’ve had a solid conversation over a 10 mile distance. That antenna might be lucky to have unity gain.

 

[tacocart99]

Hey guys. I just mounted up a Comet SSB5NMO to a Diamond lip mount on the hood of my Tacoma. Everything works great! My concern is water ingress. How would I seal the exposed threads/void space where the antenna screws into the mount threads? I see many antennas that come with a rubber gasket to solve this problem. What can I purchase at this point to make that connect water tight? Thanks for the help!

 

[Sparksalot]

Hey guys. I just mounted up a Comet SSB5NMO to a Diamond lip mount on the hood of my Tacoma. Everything works great! My concern is water ingress. How would I seal the exposed threads/void space where the antenna screws into the mount threads? I see many antennas that come with a rubber gasket to solve this problem. What can I purchase at this point to make that connect water tight? Thanks for the help!

Do you have a closeup of the point you’re concerned with. There are a couple of spots and solutions.

 

[tacocart99]

Hey guys. I just mounted up a Comet SSB5NMO to a Diamond lip mount on the hood of my Tacoma. Everything works great! My concern is water ingress. How would I seal the exposed threads/void space where the antenna screws into the mount threads? I see many antennas that come with a rubber gasket to solve this problem. What can I purchase at this point to make that connect water tight? Thanks for the help!

Do you have a closeup of the point you’re concerned with. There are a couple of spots and solutions.

Ask and you shall receive. I’m pointing at the small gap between the antenna base and mount threads. I am thinking a simple Tram 1291 NMO gasket will work. I just need a second opinion.

 

[Sparksalot]

Ask and you shall receive. I’m pointing at the small gap between the antenna base and mount threads. I am thinking a simple Tram 1291 NMO gasket will work. I just need a second opinion.

Yes that gasket would work. I have them on mine. Not as pretty, but equally effective would be some RTV.

 

[Sparksalot]

@tacocart762 here’s one of the antenna farm configurations on thecopcar. That tram gasket is under all of them. The angles are exaggerated by the camera zoom.

 

[tacocart99]

@tacocart762 here’s one of the antenna farm configurations on thecopcar. That tram gasket is under all of them. The angles are exaggerated by the camera zoom.

View attachment 177857

Lol at first I thought wow those antennas are tilted way to the side. Then I read your message. Looks good to me. Thank you very much for confirming the gasket idea I appreciate that! Enjoy Thanksgiving!

 

[Sparksalot]

Lol. I was more than 50 feet behind, trying to capture the entire scene. I cropped that to show the antennas better.

here is the full pic. We were on a portion of segment 1 of the Enchanted Rockies Trail. The mountains in the distance are just south of White Sands NM.

 

[tacocart99]

Lol. I was more than 50 feet behind, trying to capture the entire scene. I cropped that to show the antennas better.

That looks great!! Sorry I did not see you sent the full pic. They do not look bowed anymore lol.
I have another issue. Maybe you have an idea of how I can remedy it. Last night I was on a local net and my HT was not cutting it. So I got into the rig with the mobile in hopes that would reach out to them. Last nights net was simplex however the mobile did reach! When I was sitting just running off the truck battery the signal was clear as crystal. As soon as I turned the truck on and more specifically my LED headlights I could no longer hear the net. The RX was completely gone. I turned the lights off and I could hear them again. Any idea what is going on here? Would a ferrite choke fix this?

here is the full pic. We were on a portion of segment 1 of the Enchanted Rockies Trail. The mountains in the distance are just south of White Sands NM.

 

[M Rose]

@tacocart762
A guy went through this same thing earlier this year.

HAM interference with fog lights?

I am having some added static/interference when fog lights are turned on. The fog run on the factory wiring harness but are diode dynamics brand lights. The radio power takes from a block under drivers seat that is supplied via 2awg direct from battery. The antenna is on rear hatch mount. Fogs...

www.overlandbound.com

 

[tacocart99]

@tacocart762
A guy went through this same thing earlier this year.

Perfect thanks for the direction!

HAM interference with fog lights?

I am having some added static/interference when fog lights are turned on. The fog run on the factory wiring harness but are diode dynamics brand lights. The radio power takes from a block under drivers seat that is supplied via 2awg direct from battery. The antenna is on rear hatch mount. Fogs...

www.overlandbound.com

 

[M Rose]

@tacocart762
No problem...
you might want to start your own thread if that thread doesn’t answer your questions.

 

[tacocart99]

@tacocart762
No problem...
you might want to start your own thread if that thread doesn’t answer your


Copy that

 

[tacocart99]

Lol. I was more than 50 feet behind, trying to capture the entire scene. I cropped that to show the antennas better.

Just FYI the halogen bulbs seemed to have fixed the interference issue with my radio and the Tram rubber gaskets came in and sealed up the voice space nicely!
here is the full pic. We were on a portion of segment 1 of the Enchanted Rockies Trail. The mountains in the distance are just south of White Sands NM.