VHF Antennas, NGP 1/2 wave and 1/4 wave

[rkneeshaw]

I'm a new HAM and I need help finding an antenna.

Is there such a thing as a 1/4 wave no-ground-plane antenna for ~151Mhz?

I'll be primarily transmitting around 151Mhz and I want to use this antenna mount from bulletproofdiesel.com:

Third Brake Light Antenna Mount for Raptor

Due to the location, I'm convinced I'll need a non-ground-plane antenna. Otherwise the radio would only really be effective for contacts directly ahead of the truck and not behind due to the mounting location being at the rear of the roof surface area.

I'm also trying to find the shortest antenna possible without too negatively impacting performance. Because of its mounting location, I'd like to avoid a 10ft long antenna that will surely contact overhead obstacles and tree branches so I've ruled out 5/8 wave. Also I think the radiation patterns of 5/8 wave aren't exactly optimal for offroad where the truck will not always be level and possibly be in and out of valleys and hills.

I'm ok with buying both a 1/2 wave and a 1/4 wave and swapping them depending on where I'll be doing my driving. I would use the taller 1/2 wave when I know I'll be in more open terrain and the shorter 1/4 wave when I know things will be tight or if there will be parking garages to deal with. Based on my calculations a properly tuned 1/2 wave antenna for ~151Mhz should probably run about 36" tall, and a 1/4 wave should be about 18" tall.

I am finding a couple NGP 1/2 wave antennnas for the right frequency range.

But I can't find any NGP 1/4 wave antennas for ~151Mhz.

 

[Ditchplains1]

rkneeshaw,
1/2 wave for 151 would be around 37.5"; 1/4 wave would be about 1/2 that 18 3/4" or so...(This from Larson NMO VHF antenna cutting guide...).

Eddie

 

[1BAD454SS]

With the 3rd brake light mount you have to use a No ground plane antenna. I just got my rig installed this weekend. Still Tuning the antenna , got the swr at 1.4 to 1.5. Waiting on a new SWR meter to compare. I was able to talk to my fathers base ham radio about 10 miles away, ******* out his signal meter. On 151.625. Antenna length is around 18 inches, i am picking up conversations pretty far away also . Antenna does drag on some drive thru establishments but hasn't been an issue offroad.

 

[rkneeshaw]

With the 3rd brake light mount you have to use a No ground plane antenna. I just got my rig installed this weekend. Still Tuning the antenna , got the swr at 1.4 to 1.5. Waiting on a new SWR meter to compare. I was able to talk to my fathers base ham radio about 10 miles away, ******* out his signal meter. On 151.625. Antenna length is around 18 inches, i am picking up conversations pretty far away also . Antenna does drag on some drive thru establishments but hasn't been an issue offroad.

Nice looking setup!

What antenna are you using? I can't find a 1/4 wave no ground plane anywhere.

Did you use the 3rd brake light mount too?

 

[1BAD454SS]

Sorry i typo-ed the length, it is more like 38 inches tall. Got confused ,because my neighbor had a bunch of old antennas in his garage and we were trying to figure out what he had. I have the 1/2 wave NGP. Here is a pic of it mounted on my miller offroad chase light. Only thing that may work for you is this magnetic mount with a flexi whip. https://www.theantennafarm.com/catalog/sti-co-mgnt-ft-niti-6441

 

[WRCRaptor]

Sorry i typo-ed the length, it is more like 38 inches tall. Got confused ,because my neighbor had a bunch of old antennas in his garage and we were trying to figure out what he had. I have the 1/2 wave NGP. Here is a pic of it mounted on my miller offroad chase light. Only thing that may work for you is this magnetic mount with a flexi whip. https://www.theantennafarm.com/catalog/sti-co-mgnt-ft-niti-6441

Is you ant. hard mounted to the Miller dust Light or on a mag mount?

How do you like the Miller dust Light and how did you wire it?

I have been thinking about this dust light

I have been running a mag mount with 2 different ants. I think they are 1/2 and a 1/4 wave. Range is good on both but the longer ant. transmits further for sure, reception is almost the same for both.

 

[1BAD454SS]

The antenna is mounted to the miller chase light. I added some bracing underneath the top plate and drilled hole and installed the brass nmo mount. Wiring the lights , the lights are wired to my off road lights so they are only on when running offroad, didn't use them as a cargo light. Brake lights are wired to stock wiring , running lights and brake function like stock. I used my own rubber weather stripping to seal against cab , if you install they way you receive it from miller offroad you will have a major water leak. I used larger hex head bolts to attach to the cab it is very solid now with no flexing or movement even if antenna is bent all the way backwards. A lot of trial and error to get the chase light they way i wanted it. Also added my own duetsch quick disconnects for the wiring , one plug for chase lights and one plug for brake lights.

 

[1BAD454SS]

Still Waiting for parts to come, to remote mount the microphone jack , it will be mounted low in the dash.

 

[rkneeshaw]

I have been running a mag mount with 2 different ants. I think they are 1/2 and a 1/4 wave. Range is good on both but the longer ant. transmits further for sure, reception is almost the same for both.

What 1/4 wave antenna are you using?

For a mag mount it is probably NGP, and I can't find one...?

 

[14 BlackScrew RR]

Here is a good source in answering majority of your questions.

Amateur Radio VHF Options


(((73)))