Advice on vhf mobile antenna

[billdozer]

Im in need of advice on a vhf mobile antenna. i live in a low area of my county and in this area radio transmission and reception suffers quite bad,, Im a firefighter and im outfitting my personal vehicle with a radio. Im stuck between a 1/4 wave and 5/8 wave. Our dispatch center is about 20 miles away from my town, We have hilly terrain with typical country surroundings (trees fields rivers ect.)

Can anyone give any input on what i should get? I will be using a 3/4 inch nmo hole mount on the center of my cherokees roof.

Im not concerned with highth at all, just performance. I hear the taller the whip the better, but i also hear that the 18 inch 1/4 wave does good too. I prefer the 1/4 wave because its a lot cheaper, but what do you guys think

 

[home121]

I would go with the 5/8 wave ant. especially on top middle of the roof of you vehicle, no worries. almost forgot even with the ant. in the middle of roof you should get good omni directional coverage, but just alittle better coverage toward the front of vehicle, thats where there will be a bigger lobe.

 

[SCPD]

Like home121 said, go with the 5/8th. You said coverage is spotty, so you more gain. 1/4 waves are fine for flatland and not a great distance. They are a better choice in the "canyons" of a downtown city.

 

[billdozer]

Thanks for the input guys.. Anyone have a reccomendation for me as far as what brand of antenna? Ive seen the trams are priced good, but im sure theres a reason for that.. Also thought about Laird or the Maxrads.

Also the thing that worries me about 5/8 wave is the need to tune them. i dont have a vhf tuner, just a cb swr meter wich i know wont work with a vhf.. I cant really afford to have someone tune it for my freq..

 

[wyomingmedic]

Buy a Larsen NMO150 and use the included cutting chart. The antenna will last you 40+ years and many vehicles.

WM

 

[n9mxq]

+1 for the Larsen. I've beat the tar outta mine and it just keeps goin.


Sent from my iPhone using that Tapatalk thingamabobber.

 

[kayn1n32008]

Wirelessly posted (Mozilla/5.0 (BlackBerry; U; BlackBerry 9780; en-US) AppleWebKit/534.8+ (KHTML, like Gecko) Version/6.0.0.600 Mobile Safari/534.8+)

+1 here also for the Larsen NMO150. They include a cutting chart, just make sure you are cutting the correct model. Cut to your transmit frequency, and you should be fine.

 

[Rt169Radio]

Another here for the Larsen, they are really good antennas.

 

[W8RMH]

I have had good luck with Laird products and I highly recommend this one. Laird Tech B1443

 

[RodStrong]

I've had some pretty good luck with the PCTel MWV1365S. It's a no tune antenna, so you don't need to mess with cutting it if that does not appeal to you. Wide band on VHF. It works great for applications I need because I run from ham all the way up to some federal stuff in the 172 range. If you have a specific or relatively narrow area of concentration on VHF, this might not be the best for you, but regardless, it's a good all around VHF antenna. http://www.antenna.com/apg_products.cgi?id_num=10932

Good luck.

 

[Drachen_Fire]

Sounds like he's using one VHF channel. I also recommend the Larsen NMO150. It's beyond great.

 

[LtDoc]

In a lot of cases a 5/8 wave tends to do better than a 1/4 wave antenna. Not much at times, but still tends to be 'better'.
If you want it to work as efficiently as possible then tune it, or have it done. Very seldom does one be 'right' straight out'a the box.
As for the brand, I think almost any of them will be comparable, they are all the same basic antenna. I think the biggest difference is in mechanical characteristics, and cost, of course.
The biggest problem with the 'cutting charts' supplied with some antennas is that you can go too far. It's always easier/cheaper to not cut off as much to start with, cuz once you do that cutting you can't put it back. But then without a means of measuring how it's working, you can't know when it isn't really 'right', right? Oh well...
- 'Doc

 

[billdozer]

thanks doc. im currently using a 1/4 wave till i find a 5/8 wave i like. thanks everyone for the advice and input

 

[krokus]

Is the 1/4 wave working for you?

 

[billdozer]

It seems to be working ok. im not getting wx freqs as good as the 5/8 . but im picking up other freqs better. the 1/4 wave is one of the pretuned ones and wx is out of that range so i think thats got something to do with that. i havent xmitted with this one yet.

 

[W2NJS]

The usual tuned bandwidth for a 5/8 wave VHF antenna is about 6 mHz. Assuming your antenna has a center freq of 154 mHz, and an overall bandwidth of 151 to 157 mHz your NOAA wx reception on 162 should be noisy; that's perfectly normal.

 

[ks4ui]

5/8 antenna

The 5/8 wavelength antenna is the best choice if you are only interested in one VHF frequency. If more than one frequency then the frequencies need to be within a meg or two of each other. This antenna provides about 3db of gain.

A halfwave VHF antenna will profide 2.5db of gain over a range of VHF frequencies.

The VHF quarterwave antenna provides no gain but works well over a range of VHF frequencies.

Gain helps in some areas but don't expect drastic results from either the 5/8 or halfwave length VHF antennas.

 

[jhooten]

Gain is not always the answer. An antenna is not some magical device that produces extra power. The gain comes by reshaping the radiation pattern. If you are down in the valley and the repeater is on the mountain a 5/8th that squirts signals out to the sides is not the best choice. The higher radiation angel of the 1/4th wave will get into the repeater when the flattened pattern of the 5/8ths is going into the hill side.

 

[mmckenna]

The nice thing is that NMO's are about as standard as you can get, and 1/4 wave antennas are cheap. Being able to swap back and forth easily is a good way to test things. Blanket statements saying that one type of antenna is better than another tends to suggest a lack of real world experience. Like Jerry said, there is nothing magical about antennas, they are bound by the law of physics. If the signal is bad in your valley, switching from a 1/4 wave to a 5/8 wave likely won't make a huge difference. It might reduce some noise, but don't expect a night and day difference.
Certainly, try a 5/8ths antenna, it'll probably help a bit, but don't expect to go from a noisy signal to full quieting by just changing antenna types.
Don't forget to look at the -entire- system. Keep your coaxial cable runs short. Use the right connector on the cable to match what's on the radio. Proper installation is important. Make sure you have good power connection to your radio, and make sure the radio is properly grounded.
These things as a whole will help improve your received signal, but don't expect the antenna alone to work miracles.