Antenna: 2m vs. 2m/440

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rfhall50

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Buying a new roof mount NMO mount for my truck. Will be used on a 2m radio. There seems to be a larger selection of dual band 2m/440 antennas as opposed to 2m only. Will a dual bander work as well as a 2m only antenna? Am I shooting myself in the foot getting a dual ? Thank you.
Bobby
 

mmckenna

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Yes, a dual band will work fine. Since 2 meters is the lower frequency/longer wavelength, it just looks like a 2 meter antenna.

Keep in mind, though:
A 2 meter quarter wave is an odd 1/4 wave of 70cm. I've used 19" quarter wave whips on dual band radios with very good results. Putting the antenna on an analyzer shows it does both 2m and 70cm just fine. Using an SWR meter, the SWR was actually lower on UHF compared to VHF. This was on a full size pickup roof.

Nice thing about the 1/4 wave is that they are very low profile, way more durable that the amateur/consumer grade antennas, and really cheap. Should't have any problem getting one for $10.

I don't buy the amateur grade antennas, had too many issues with the one I had. A commercial grade/known USA brand antenna, that is properly maintained, will outlast your truck.
 

Sporrt

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Buying a new roof mount NMO mount for my truck. Will be used on a 2m radio. There seems to be a larger selection of dual band 2m/440 antennas as opposed to 2m only. Will a dual bander work as well as a 2m only antenna? Am I shooting myself in the foot getting a dual ? Thank you.
Bobby
Larsen 2/70b (black) or 2/70c (chrome) NMO are worth looking at. R&L electronics has a good price, but they seem to sell out.

Half wave on 2 meter, collinear on 440
 

mmckenna

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Yeah, Larsen is a good choice.

You'll often find that the higher quality commercial antennas are cheaper than the amateur/consumer grade stuff.

Also, avoid Tram/Browning and any of the cheap Chinese brands. While you may save a few bucks in the short term, the quality of those antenna brands is pretty crappy. You'll end up replacing it in the long run.

I've got Larsen commercial antennas that I've had for 20+ years and they are still working great.
 

jwt873

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I have an NMO mount smack in the middle of the roof of my car. I also have a Larsen 5/8 Wave 2 meter antenna and a Larsen 2/70 dual band antenna.

Most of my driving is on the highway. I sometimes put my Kenwood TH-D72 in packet mode and use it as a tracker on 2 meters. This lets me look at my packet history on the aprs.fi maps and see how well I'm reaching the local digipeater as I travel around.

The 2/70 antenna does a bit better. The SWR on both antennas has been adjusted down to the order 1:2 to 1 using a quality antenna analyzer. I'm guessing that the 2 meter 5/8 is suffering a bit because it's bent over noticeable at highway speeds. The 2/70 antenna is shorter and stiffer. It doesn't bend in the wind.

It really wouldn't hurt to get a dual bander... One day you might buy a UHF capable radio.
 

N4KVE

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I don't buy the amateur grade antennas, had too many issues with the one I had. A commercial grade/known USA brand antenna, that is properly maintained, will outlast your truck.
My Larsen 2/70 antenna has outlasted 5 vehicles. But a simple 19" VHF antenna works great on both bands.
 

mmckenna

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For those that operate simplex, a 1/4 wave really reduces range.
Sure, maybe, but it depends.
I'm in coastal/central California. There isn't a place I can go in this state and not see hills or mountains on the horizon, or Pacific Ocean. I've never had an issue reaching who I need to talk to with a 1/4 wave. While VHF will sometimes get a bit beyond the horizon, it is mostly a line of site thing. If your signal gets there, it works. Adding additional gain can help on reception, especially when talking to someone on a portable, in a building, or with a crappy antenna.

Higher gain antennas can be a benefit at times, but there are some trade off's. Longer antennas are not always a good choice, especially on taller vehicles. At highway speeds (or greater) longer antennas will flex back and reduce performance.

After many years of switching back and forth between a Larsen NMO-150 (5/8'ths wave) and a 1/4 wave, I finally settled on the shorter antenna. It fit my needs well. It's short enough on a full size pickup to not get in the way too much. On my wife's Ford Escape, it still fits in the garage.

On the flip side, I have a Polaris Ranger UTV. VHF mobile mounted in there. Since a good ground plane is hard to achieve on a roll cage, I went with a 1/2 wave whip. It's actually working very well. With a spring at the base it's flexible enough to take tree branch strikes, which it's done several times at speed. In fact, the end of the whip has a bend in it about 3 inches from the end.

Individual results may vary, and your specific location plays into that a lot. I know out in the central US, on the plains, it's common to see public safety using higher gain antennas. Out here, it's nearly unheard of, 1/4 waves will hit the repeaters just fine.

In the OP's specific case, he's considering a dual band. A 1/4 VHF will work quite well on 70 centimeters. A 5/8th's VHF won't. A 5/8th's VHF will work well on the 6 meter band, though.

The other big benefit to a 1/4 wave antenna is that they are very broad banded. I use my VHF radio for both work and amateur use. I've got work frequencies in the radio that stretch up near 159MHz. The amateur stuff, down to 144. On vehicles that belong to agencies that might need to interoperate with federal agencies, especially forest fire or interoperability with federal law enforcement, the frequencies can easily spread up to nearly 170MHz. It's difficult to get a 150-170MHz range out of a 5/8th's wave antenna without some compromise near the edges. On a 1/4 wave, it's not an issue.
I've put 1/4 wave antennas (permanent mount, center of vehicle roof) on an analyzer and it'll show a less than 1.7:1 SWR from 144 to 174MHz. 5/8'ths roll off a whole lot faster.
Not a big deal for amateurs, especially when only trying to cover 4MHz of the VHF band. Big deal for public safety, though. But, yeah, the OP isn't public safety, so not really relevant.
 

cmdrwill

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This is what I run, never a problem. Comtelco A1511B. Also have a A1511 on service truck for 20 years. A dual band is available A1531A.
 

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jbantennaman

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Maybe I will shoot myself in the foot for asking, but what do you mean by radio?
I think the generic term Radio is used too loosely.
In my case - radio means the Yaesu FT 8900R in my truck.
I also have a second in the shack.

For most people - radio to them means some cheap handheld.
For someone asking this question - tells me that they don't understand how radio works.
If all I was going to talk was a couple of miles to the local repeater, maybe a handheld and cheap roof top antenna would be all that i would need.
But where I live, you wouldn't have anyone to talk to,so it would be a waste to cheap out the handheld route.
The nearest group of hams is 40+ air miles away!
For them - Radio - means their own local repeater, that they use like a telephone.
In the mountains of western Pa, if you don't have 40 / 50 watts and a mountaintop location, you might as well forget trying to play ham radio, just not a lot of people on the air anymore, and no one calling CQ.

NMO 270 is also my antenna of choice.
 

AZDon

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I actually use an amateur dual band antenna/NMO antenna on the roof of my house daily, it works great. Yes, a VHF 1/4 wavelenth antenna loads on VHF and UHF but it doesnt radiate well on UHF. SWR can be deceiving. I have made hundreds of tests comparing differant antennas on the same mount using the same cable to the same radio. Of course there is nothing like using a dedicated antenna for each of the amatuer bands but, the differance between a dedicated omni antenna is not that much more than a dual band. It will make a differance at the extremes but when you factor in costs, a well desinged dual band antenna is hard to beat.
 

K5MPH

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Yeah, Larsen is a good choice.

You'll often find that the higher quality commercial antennas are cheaper than the amateur/consumer grade stuff.

Also, avoid Tram/Browning and any of the cheap Chinese brands. While you may save a few bucks in the short term, the quality of those antenna brands is pretty crappy. You'll end up replacing it in the long run.

I've got Larsen commercial antennas that I've had for 20+ years and they are still working great.
I have had an Browning BR- 180, 2m/440 for 7 years and still works fine no rust and the swr are still very good.....
 
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