7/800 NMO Antenna

[KN4EHX]

I’m sure this has probably been addressed before, but I’m going to throw it out there and perhaps light a fire with this question.

I’ll need to make a few comments on my setup to give you all an ideal of what I’m working with. 35 watts mobile on a statewide trunked radio system. I work in emergency management - in the mountains -I tend to end up in all the poor reception places.

I’ve got a Harris full spectrum antenna V/U/7-800 antenna but the base is absolutely massive and I’d prefer to have a dedicated 7-800 MHz antenna. In my experience the salt shaker (phantom) antennas work okay for downtown but we’re still building up the system in my neck of the woods so I’m thinking something higher gain would be better. My catch 22 with the Harris antenna is the gigantic base. Gigantic might be a bit of an understatement and it occasionally gets very colorful names by my friends. Simplex is also in the equation whenever we’re out and in fringe areas.

If anyone has experience with a particular antenna that does well in this type situation please let me know the manufacture and model number if possible.

I do drive a SUV and in classic Tennessee fashion with lots of rain and low hanging branches so the antenna does need to be durable enough to get smacked around some. Back story: I exploded a low band VHF antenna coil on a wet branch too early in the morning on my way to an emergency. Talk about waking you up better than a cup full of espresso! I almost needed to change pants. I’ve learned to be a little more mindful of the branches now. Although I have a few areas close to my home that I don’t have a choice but to hit them.

Thank you all for reading and especially to those who give good answers!

 

[mmckenna]

Those old Harris multiband antennas were big. I'm getting ready to buy a bunch of XL-200M's and met with Harris at IWCE. They've switched to the goofy looking twin whip Stico antenna due to roof damage and antenna failures on those old ones.

If you want to keep the full capability of your radio, you could try the Stico that Harris resells now. It's flexible right down to the NMO base. STI-CO® Tri Band Roof Mount Antenna | STI-CO® Antenna Solutions

Or, try the new Larsen NMO-150/450/758SF. Those have a flexible whip and a spring on the base. I'm running two on my work truck, one on the VHF radio, one on the 800MHz radio. Haven't tried it simplex, but they are working well on both bands.

Before those, I had the Larsen NMO-800 on the work truck. I've hit a few branches/low parking garages with that one and never had any issues. It's been up overgrown access roads many times and thwacked a lot of low tree branches.

Or, go 1/4 wave whip.

 

[KN4EHX]

Those old Harris multiband antennas were big. I'm getting ready to buy a bunch of XL-200M's and met with Harris at IWCE. They've switched to the goofy looking twin whip Stico antenna due to roof damage and antenna failures on those old ones.

If you want to keep the full capability of your radio, you could try the Stico that Harris resells now. It's flexible right down to the NMO base. STI-CO® Tri Band Roof Mount Antenna | STI-CO® Antenna Solutions

Or, try the new Larsen NMO-150/450/758SF. Those have a flexible whip and a spring on the base. I'm running two on my work truck, one on the VHF radio, one on the 800MHz radio. Haven't tried it simplex, but they are working well on both bands.

Before those, I had the Larsen NMO-800 on the work truck. I've hit a few branches/low parking garages with that one and never had any issues. It's been up overgrown access roads many times and thwacked a lot of low tree branches.

Or, go 1/4 wave whip.

Always good advice from you. Thank you.

 

[KN4EHX]

If you want to keep the full capability of your radio, you could try the Stico that Harris resells now. It's flexible right down to the NMO base. STI-CO® Tri Band Roof Mount Antenna | STI-CO® Antenna Solutions

That is ummmm….. unique. Not gonna win any beauty contest anytime soon. Yeah…. I’m not really sure what to say about that. I make a lot of jokes about j pole antennas because when I started life as a ham a few years ago that was THE antenna to have. I’m starting to wonder which one of those old dudes got a job with STI-CO. I’m imagining a bunch of people sitting around a table talking about the wonders of the jay poe and how they could slap it on top of a car.

The spiders tend to go from one antenna to the next so they will be pretty happy about this design. Flies and mosquitoes maybe not so stoked. Although STI-CO can argue it is good for the environment.

Maybe I’m getting older. Call me a traditionalist haha.

 

[mmckenna]

I don't think it's a J-pole. I think it's just a two element antenna. VHF 1/4 wave is 3/4 wave on UHF. Add a 700/800-ish whip and call it done.

I agree with what you said, looks like something you'd see magnet mounted to the top of the wife's minivan, next to the amber strobes and "when all else fails!" bumper sticker in a ham-fest parking lot.

I won't be buying those antennas for our radios. Probably going with the Larsen antennas if they continue to perform well. Anything Stico is expensive. Any antenna sold by a mobile radio manufacturer is also overpriced.

 

[crazyboy]

Or, try the new Larsen NMO-150/450/758SF. Those have a flexible whip and a spring on the base. I'm running two on my work truck, one on the VHF radio, one on the 800MHz radio. Haven't tried it simplex, but they are working well on both bands.

I'm also a fan of the Larsen NMO 150/450/758, my go to multi band antenna. Performs better than I had expected.

 

[jeepsandradios]

I run the Larsen NMO but it you do put it on sweep the 700/800 band. I didn't see the best results in the channels I use so switched out to a 1/4 wave on 800 at this point. The Larsen is a good antenna for V/U and still run 4 on my truck. Driving to tower sites with low branches have not caused any damage as of yet on my F150. YRMV

 

[merlin]

My lot, I have the 'salt shaker' Works fine mobile.
I have PC-TEL and Motorola. Rugged and 3Db gain or better.

 

[merlin]

Larson is the worst antenna in my encounters.

 

[krokus]

Larson is the worst antenna in my encounters.

What sorts of issues have you had with Larsen?

 

[rescue161]

We have always had good experiences with Larsen.

 

[trentbob]

Larson is the worst antenna in my encounters.

That's what makes the world go round LOL. I use the Larson 150/450/758. Excellent overall performance. There's always some compromise with a so called tri-band antenna.

 

[merlin]

What sorts of issues have you had with Larsen?

Maybe just the antennas I wind up with. My take though is cheaply made, poor QC. Made in China I think, not like the older Larsen.
I have a VHF, supposedly newer and simply will not tune. Best SWR is way off band and 3: to 1

 

[merlin]

That's what makes the world go round LOL. I use the Larson 150/450/758. Excellent overall performance. There's always some compromise with a so called tri-band antenna.

I wonder what those look like on a VNA.

 

[tweiss3]

I wonder what those look like on a VNA.

Check this thread out: Larsen Multi-Band antennas

 

[jeepsandradios]

I don't have my sweep data for the Larsen but here is my Motorola Tri-Band. The Larsen swept very close.

 

[Anderegg]

I am also looking for a best single purpose 7/800 roof antenna. I have I think a Larsen something, it's old, and around 50-60 RSSI on an APX it can't get an affiliation to hit the repeater after multiple attempts. Looking for 700 and 800, but mostly need 800 punch with 700 being a secondary need. With what is out there, are all the 17" coil in the center antennas pretty much the exact same performance? I have a double stacked thing I got a while back, but it doesn't improve RX or TX performance when tested. I am now seeing stick 5/8 wave 7/800 whips that almost look like UHF 5/8 waves. Are those better, worse, same?

As for the 150/450/758, I have one, and it gives a couple of RSSI points less than the dedicated 800 antenna using now. Really impressed with that tri-band for what it is, especially since they seem to have optimized it for 7/800 TX.

Paul

 

[mmckenna]

I've played around with a lot of antennas for 800MHz on top of my truck at work.
Through all the marketing hype and gain numbers, there really isn't a lot of difference.

Yeah, a 5dB gain antenna will add a bit of signal to the radio, but getting from -125dB RSSI to -120dB RSSI only makes so much difference on the fringes. There may be a short piece of road where the higher gain antenna will get a bit more range out of the radio system, but it's not going to be a very long stretch of road. With modern radios and sensitive receivers, they work pretty well with what you can give them. More depends on the antenna at the repeater end. If you are within the coverage footprint of the system, they are often designed for portable radio coverage, so you don't need much to get a usable signal.

I can swap between a 1/4 wave antenna, the 3dB antennas and the Larsen multiband and see a slight change on the RSSI display, but audio wise, it doesn't really matter.

1/4 wave antennas are cheap, durable and they work well. I've spec'd those out for everything at work. I'm running the the Larsen NMO-800 3dB gain antennas on the police cars since they get a bit more out on the fringes and sometimes do some interoperability stuff on simplex, but it really doesn't make much of a difference. They don't care so much about all the antennas….

If you are looking at 700 and 800MHz, then the big benefit to the 1/4 wave is that it's really wide band and will give you a nice low SWR across both bands.

Theoretically higher gain antennas can work against you in some applications. The narrower beamwidth can cause issues if you are on less than level surfaces. Higher gain antennas can also suffer from picket fencing a bit more.

But like I said, 1/4 wave. Cheap. Durable. Reliable.

 

[Anderegg]

I went and ordered a cheap $12 Laird NMO3HD800B standard 806-866MHz, no pins, no springs, just a thick whip with a tab. Also ordered up an expensive $50 Laird BB7603R, which according to Antenna Farm is a 5/8 wave 7/800 with 7 inch whip. I was expecting some sort of cool UHF 1/2 wave type new design, but what I received was a little 1/4 3" whip on top of an elastomer spring. The good news is the $12 antenna beat out my current antenna, which was already slightly better than my old trusty NMO800 of years past. Affiliation success at my staging area is much much improved along wiht a few RSSI points. The Laird is horrible on 800MHz, with RSSI of 25 vs 35 on the other antennas. On 700MHz, it seemed to math the standard type antenna, so perhaps it came pretuned for 700MHz, since it does have instructions to loosen a nut and adjust length for best VSWR. Both antennas are speced at 3db, although the little 1/4 really wasn't able to spit out enough RF to affiliate compared to the big antennas.

BB7603R

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Paul