EM Wave Multiband antenna sweep

[prcguy]

Is the LMR-1 in the middle of a big roof or similar? They seem to do better at the edge of a roof or trunk lid on VSWR where other type antennas don't do as well. This should only affect VHF hi band and UHF on up is usually fine in the middle of a roof.

QUOTE="BMDaug, post: 3734212, member: 1618296"]
I’m really excited to see the outcome of this! I have an LMR-I and I love it, but I’ve been having issues with it on one of my vehicles. The SWR is unusable and I can’t figure out what’s going on with it.

-B
[/QUOTE]

 

[BMDaug]

Is the LMR-1 in the middle of a big roof or similar? They seem to do better at the edge of a roof or trunk lid on VSWR where other type antennas don't do as well. This should only affect VHF hi band and UHF on up is usually fine in the middle of a roof.

It’s on a mag mount and I’ve tried it everywhere it will stick! Center, front (which makes the car look like a unicorn), all four corners… I can’t figure it out! The radio is not grounded to the vehicle, as it has its own power source, but my understanding is that the antenna should capacitively couple with the body of the car without any actual ground strapping. 🤷🏼‍♂️

-B

 

[prcguy]

The COMPACtennas I've tried love mag mounts. Do other antennas work on the same mount?

It’s on a mag mount and I’ve tried it everywhere it will stick! Center, front (which makes the car look like a unicorn), all four corners… I can’t figure it out! The radio is not grounded to the vehicle, as it has its own power source, but my understanding is that the antenna should capacitively couple with the body of the car without any actual ground strapping. 🤷🏼‍♂️

-B

 

[BMDaug]

The COMPACtennas I've tried love mag mounts. Do other antennas work on the same mount?

So I haven’t had any other antennas to play with since I got this particular mount. I had a couple of stico triband antennas (another you should add to your test), but I trimmed them to make a dipole and removed the NMO mounts so they won’t be right for testing any longer or I’d send you one! The stico antenna is the one Harris sold with XG100Ms. It’s two whips of different lengths coming from a single NMO mount.

Anyway, I’m gonna borrow some random whips from our comms director to see if it’s the mount (or the attached wire) but it is a Larsen NMOMMRDSN with an N connector, bought from the AntennaFarm so it’s not random crap.

-B

 

[mmckenna]

The stico antenna is the one Harris sold with XG100Ms. It’s two whips of different lengths coming from a single NMO mount.

I think I may have ordered one of those with my radios. With the supply chain delays, not sure when I'll get it.

But, Sweet Jebus, those are way overpriced. Stico makes nice stuff, but between their high prices and the Harris markup, I'm not taking them seriously as an option.

so it’s not random crap.

Always a good disclaimer. Too many junky Chinese products out there.

 

[prcguy]

I would verify your mount is ok before condemning the COMPACtenna. I would love to have one of the Sti-Co multiband whips for the test but we have most of the common multiband commercial and scanner models on the market already and a few hamster models, 12 so far to test.

So I haven’t had any other antennas to play with since I got this particular mount. I had a couple of stico triband antennas (another you should add to your test), but I trimmed them to make a dipole and removed the NMO mounts so they won’t be right for testing any longer or I’d send you one! The stico antenna is the one Harris sold with XG100Ms. It’s two whips of different lengths coming from a single NMO mount.

Anyway, I’m gonna borrow some random whips from our comms director to see if it’s the mount (or the attached wire) but it is a Larsen NMOMMRDSN with an N connector, bought from the AntennaFarm so it’s not random crap.

-B

 

[BMDaug]

I would verify your mount is ok before condemning the COMPACtenna. I would love to have one of the Sti-Co multiband whips for the test but we have most of the common multiband commercial and scanner models on the market already and a few hamster models, 12 so far to test.

Ya, I will, but check out these weird sweeps and the placement photo… (sorry for the crappy photos of the sweeps, it’s really bright outside!) The VHF 136-174 sweep is especially bad… SWR at 136 is like 8:1!!!

-B

 

[cbehr91]

I’m really excited to see the outcome of this! I have an LMR-I and I love it, but I’ve been having issues with it on one of my vehicles. The SWR is unusable and I can’t figure out what’s going on with it.

-B

Is the metal tab at the antenna making good contact with the NMO mount? Sometimes you have to (carefully) pull the metal tab on the antenna down in order for it to make good contact with the mount.

 

[BMDaug]

Is the metal tab at the antenna making good contact with the NMO mount? Sometimes you have to (carefully) pull the metal tab on the antenna down in order for it to make good contact with the mount.

Ya, I’ve carefully bent it out to make sure of exactly that! What’s really strange is that when I hold the mag mount in my hand, with the LMR-I attached, the SWR is lower than when I put it on my vehicle!! That I really don’t get. I got some other antennas and they seem to work as expected, though they are not triband. They bottom out at like 1.2:1 at their designed resonant frequency… I also borrowed another mag mount but I need to dig out an SO239 to N adapter to try it out…

I didn’t mean to hijack this thread and can start another one if that’s preferred!

-B

 

[k7ng]

Very much anticipating prcguy's antenna test results. Glad someone had the resources to do such testing.