Low profile antennas

[Radio Guy]

Here are some black trunk lip NMO mounts real cheap surplus like $10. I just got two in the other day and they look fine and are made by a major antenna company. I usually use Laird brand but these look to be very similar. https://www.ebay.com/itm/225862639810

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[jav_eee]

Here are some black trunk lip NMO mounts real cheap surplus like $10. I just got two in the other day and they look fine and are made by a major antenna company. I usually use Laird brand but these look to be very similar. https://www.ebay.com/itm/225862639810

I installed one of these and my SWR kinda sucks. I cut a bit off of the cable when I added the connector, hope that didn’t change some resonance.

Those set screws should dig into the paint to achieve grounding, right?

 

[Radio Guy]

I installed one of these and my SWR kinda sucks. I cut a bit off of the cable when I added the connector, hope that didn’t change some resonance.

Those set screws should dig into the paint to achieve grounding, right?

Trunk lip mount on the hood near a hinge? Any pictures? Cable length doesn't matter and the shorter the better.

 

[jav_eee]

Trunk lip mount on the hood near a hinge? Any pictures? Cable length doesn't matter and the shorter the better.

Yeah exactly as pictured above on the silver jeep, drivers side. I’ve confirmed grounding via the set screws and nmo base. Center pin is good, no issues on cable or connector either.

I’ve always understood cable length to not really matter but it’s the only thing I can think of as being a factor.

 

[Radio Guy]

Yeah exactly as pictured above on the silver jeep, drivers side. I’ve confirmed grounding via the set screws and nmo base. Center pin is good, no issues on cable or connector either.

I’ve always understood cable length to not really matter but it’s the only thing I can think of as being a factor.

Are you checking VSWR with an antenna analyzer? If so check from 400-500MHz and see if it dips somewhere or if its just bad everywhere. I can stick a 1/4 wave whip on mine tomorrow and test. I do have aluminum tape under the curved cowl pieces behind and to the outside of my antenna mounts. That adds a little more ground plane but it shouldn't be that critical at UHF. I did the ground plane improvement more for VHF.

 

[jav_eee]

Are you checking VSWR with an antenna analyzer? If so check from 400-500MHz and see if it dips somewhere or if its just bad everywhere. I can stick a 1/4 wave whip on mine tomorrow and test. I do have aluminum tape under the curved cowl pieces behind and to the outside of my antenna mounts. That adds a little more ground plane but it shouldn't be that critical at UHF. I did the ground plane improvement more for VHF.

Yeah I’m using a NanoVNA and I get OK SWR on VHF and higher SWR on GMRS freqs with a Comet 2x4SR but with my ol’ trusty Larsen NMO270 the measurements are whacky. Almost looks like a tuning issue but I don’t think the Larsen is tunable.

I’ve got some aluminum tape that I can do the same with.

C for comet, L for Larsen

 

[jav_eee]

Sorry to hijack your thread, @GWolgamott !

 

[chorky]

I'll bring it back. But do share your results and fix!!

So read a bit on some of the low profile antennas. Seems that yes not ideal for hardcore radio heads or extended range. But my question for those that actually do have these and mounted on the cowl do they get the job done? In Michigan so no real long extended flat areas, no mountains, and mostly wooded mixed with small hills. Would be used mainly for just trail riding in small groups. So no need for it ever have more then say few miles of range.

There is a saying or two I live by. Which comes after being left high and dry multiple times by people who shouldn't leave you high and dry.

Expect to Self Rescue. No one is coming.

It's been said before but I think the copyright of 30 seconds out. Anyway, I totally understand the desire for lo profile antennas, kinda. And in 98% of the time it will probably work fine for a trail ride. But here is a situation. Last year on a group trip with I think it was 12 vehicles. Between the first and the last, in some places was more than 5 miles for various reasons. Stoping for a photo, fast drivers, mechanical issues, having to pee, whatever. Some were new at this 'off road' thing and didn't understand the whole, wait for the vehicle behind you at a turn before continuing, thing. Multiple times through the trip it required the middle vehicle to pass the word between the front and rear depending on things happening - other quads wanting to pass the whole group, and oncoming vehicle, even construction equipment and other road hazards. It was an annoyance for sure, as a lot of times I was that 'repeater'.

Here is another situation. One group member had to take a detour and part from the rest of the group for one day of travel. The final camp location that night was all understood so there were no worries there about someone getting lost. But, the main group got held up. By several hours due to a variety of unknown road conditions. First it was a rougher than planned road and a few were towing 'off road' trailers. Then it was a few trees down (I think I was one of the only ones with a saw). Then there was some major road construction going on for about 15 miles that made for some of the lesser capable vehicles have a really difficult time due to the road basically turned into 15" deep soft sand. Needless to say, it was getting later and the fear was the one who parted might be getting worried at camp wondering where we are. And because we ended up taking a detour, they wouldn't find us on the primary previously agreed upon route. Myself and one other had the highest power radio and antenna. We tried broadcasting but got nothing in return. I think I even tried on a few repeater channels, later to find out there are only 3 GMRS repeaters in this state. At the end of the day, all turned out fine. But, the one waiting for us at camp did in fact get pretty nervous. At one point they heard my broadcast, but because their radio was not sufficient I was unable to hear a return. I also had sat coms, they didn't. Nobody got hurt. But the what if is real. And in the event that person got worried enough to start searching for us, it could have ended up bad especially if they never found us and feared the worst calling search and rescue, or if we arrived camp to find them not there only for us to also call search and rescue.

The distance between us was 25 miles when we realized we needed to try and make contact, which was already several hours of being late, and due to road conditions, was another few hours.

So, when there is the ability for a few more dollars to get something that is significantly better than a low profile mount, which we all know has compromises, I just will never understand the purposeful choice for a low profile. But then again, I have been left high and dry so many times and have had to rely solely on myself to be ok that I refuse to make a purposeful choice that leaves somebody else high and dry. It is worth considering, not skimping. Especially if you do plan to have communications. Even in hilly terrain, that low profile mount might only get you a couple miles, and often times groups can easily get more than 5 miles apart.

Expect the unexpected.

 

[GWolgamott]

Because most people I've gone with use handhelds. Just wanting something with a little extra power and was asking if the low profile worked. If I were not driving in narrow woods that may snagging it on or in large groups in those situations you described wouldn't even be having the conversation of low profile antennas though. Wouldn't be buying a 15w radio for that matter if needed more, ha.

 

[Radio Guy]

I checked my NMO mount on hood hear a hinge with a Larsen NMO270, Tram 6" 1/4 wave UHF whip and broad band Comet 2X4SR antenna on both VHF and UHF. All antennas performed as expected with good VSWR over their rated frequency range.

Larsen NMO270

Tram UHF 1/4 wave

Comet 2X4SR

Mounting location on my truck

You can see the VSWR is under 2:1 over an impressive frequency range on all antennas.

 

[RogMac1175]

So read a bit on some of the low profile antennas. Seems that yes not ideal for hardcore radio heads or extended range. But my question for those that actually do have these and mounted on the cowl do they get the job done? In Michigan so no real long extended flat areas, no mountains, and mostly wooded mixed with small hills. Would be used mainly for just trail riding in small groups. So no need for it ever have more then say few miles of range.

I have a very short antenna and the FM reception degraded a tiny bit. I don't really listen to the radio though, so I don't necessarily care. I do like the look of the short antenna.

 

[GWolgamott]

I have a very short antenna and the FM reception degraded a tiny bit. I don't really listen to the radio though, so I don't necessarily care. I do like the look of the short antenna.

As far as my regular radio yeah i lost a bit of reception when i took the factory off. For that i was more concerned about the denting the factory antenna left on the pillar then my reception. I put a smaller stiffer antenna that wasn't going to whip into the body as bad.

 

[WesternMojave]

Trunk lip mount on the hood works great, mechanically and performance wise.

Did a similar intall. Used two Larsen mounts, one for the antenna for my Midland MXT275 and another on the other side of the hood for the WeBoost.

 

[Radio Guy]

Did a similar intall. Used two Larsen mounts, one for the antenna for my Midland MXT275 and another on the other side of the hood for the WeBoost.

Are you able to measure VSWR? That might be helpful for others considering the same setup.

 

[WesternMojave]

Are you able to measure VSWR? That might be helpful for others considering the same setup.

Finally got around to checking the SWR readings. Using a Surecom SW-102, I tested the Midland ghost antenna and the Midland MXTA26. For the ghost antenna, I got a consistent 2.2 across the GMRS bands. For the MXTA26, I 1.3 across channels 1-7 and 1.9 across 15-22.

Trying to tune the MXTA26, I found like many others that they cut the antenna too short. Extending it out as far as I could I got channels 1-7 down to 1.05 and channels 15-22 down to 1.72. I need to go back and check my soldering on the coax connector and also look for a different antenna.

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