GMRS Antennas

[Bonnie6G]

Anyone have experience with GRMS antennas? I appreciate they need to be tuned to the frequencies you’re looking to use. I really like the look of the low profile stubby antennas, but not sure if or how you’d tune one of them. Do they sacrifice performance at all for looks? I see ruggedradios has a low profile UHF antenna rated for 450-480 MHz. Is that close enough for a radio that needs 462-467MHz?

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[Theherofails]

Put simply, stubby antenna are never going to give you the max range for the frequency band you are talking about (GRMS).

Antenna length is inversely proportional to frequency.. in simple terms, the frequency determines the ideal length of antenna, and 465mhz has an ideal quarter wave of roughly 15cm (6-7"). This means an ideal short (quarter wave, or one quarter the total height of the frequency) antenna would be approx 15cm long for maximum transmission and reception in the GRMS band.

Stubby antenna work by coiling the appropriate length of antenna wire in a small package, but there are losses involved when doing it this way.

If none of this makes sense, that's fine. The take away is you'll lose effeciency and range with a stubby. How much will be dictated on the exact design of the antenna.

Will it matter? Likely not. GRMS is never going to be a long range communication source. Does it matter if you lose 20% range? Eeh.

You can see this in practice by looking the Bronco. Wonder why it has the giant whip antenna for radio instead of the stubby found on the Ranger? Ford knows their customer base listens to AM, which gets much worse reception with a stubby antenna. You just cant fake physics.. They had to go with the long antenna to assure AM reception in rural settings. Ranger is primarily sold overseas, which doesn't really care about AM bands. Bronco is a primarily American vehicle, so it mattered a lot more.

 

[Bonnie6G]

Put simply, stubby antenna are never going to give you the max range for the frequency band you are talking about (GRMS).

Antenna length is inversely proportional to frequency.. in simple terms, the frequency determines the ideal length of antenna, and 465mhz has an ideal quarter wave of roughly 15cm (6-7"). This means an ideal short (quarter wave, or one quarter the total height of the frequency) antenna would be approx 15cm long for maximum transmission and reception in the GRMS band.

Stubby antenna work by coiling the appropriate length of antenna wire in a small package, but there are losses involved when doing it this way.

If none of this makes sense, that's fine. The take away is you'll lose effeciency and range with a stubby. How much will be dictated on the exact design of the antenna.

Will it matter? Likely not. GRMS is never going to be a long range communication source. Does it matter if you lose 20% range? Eeh.

You can see this in practice by looking the Bronco. Wonder why it has the giant whip antenna for radio instead of the stubby found on the Ranger? Ford knows their customer base listens to AM, which gets much worse reception with a stubby antenna. You just cant fake physics.. They had to go with the long antenna to assure AM reception in rural settings. Ranger is primarily sold overseas, which doesn't really care about AM bands. Bronco is a primarily American vehicle, so it mattered a lot more.

10-4, thanks. That makes sense. I figured the stubby would coil the antenna, but wasn’t sure how that might affect it’s transmission/reception ability. It’s a bummer, cuz I do like the low profile antenna’a looks compared to a skinny whip poking up.
What about the extension cable that ties the antenna to the radio body? Does that come into play with regards to TX/RCPT or is that after the ground plane in the system?

 

[BRKOBILLY2]

I wanted to buy this but didn't pull trigger and now looks sold out. Do you think this stubby is likely good when not separated by big mountains?

 

[Bonnie6G]

I wanted to buy this but didn't pull trigger and now looks sold out. Do you think this stubby is likely good when not separated by big mountains?

I’m clearly not an expert on this topic, but I don’t think any radio is gonna work when separated by big mountians without using a GMRS repeater system. I’m in Colorado and there’s unfortunately only a handful of them scattered around so far. Line of site should be fine though, so for comms within a group on a trail it’d probably be fine, but I wouldn’t count on it to call for help if you’re separated or out alone in the mountains. Anyone can feel free to correct me if I’m wrong here.

 

[Theherofails]

10-4, thanks. That makes sense. I figured the stubby would coil the antenna, but wasn’t sure how that might affect it’s transmission/reception ability. It’s a bummer, cuz I do like the low profile antenna’a looks compared to a skinny whip poking up.
What about the extension cable that ties the antenna to the radio body? Does that come into play with regards to TX/RCPT or is that after the ground plane in the system?

That entirely depends on what type of antenna you get and how you mount it. The ground plane is simply the other half of your dipole (two pole) antenna. Think of it as the bottom half of the antenna.

That could be any combination of the vehicle itself or the wire running to the antenna. Or you can get antenna without a ground plane at all, but you do lose range and efficiency, once again. Most stubby antenna are this way, which is part of the loss of efficiency.

Everything is a trade off with radio antennas. If you are really trying to stretch your range, you want a whip antenna that is 5/8ths the frequency range you are working in, and you want it grounded properly to your vehicle with a grounding strap. A new vehicle like the Bronco should do great in this regards as I would expect the ground to be 'clean'. A lot of poor quality electronics can introduce noise into your ground path and that will feed back into sensitive electronics.

Like I said though.. If you aren't trying to squeeze EVERY single last foot out of your range, go with what you like. The chances are that everyone else in your group will be running the walmart special with no thought at all put into their radio setup and you'll be limited by them anyways.

 

[Theherofails]

I wanted to buy this but didn't pull trigger and now looks sold out. Do you think this stubby is likely good when not separated by big mountains?

Is that about 25w? I'm not super familiar with GRMS radios by model. My comms training is military, so I'm used to bigger equipment.

If that's about 25w, factoring in the stubby, you will likely get a SOLID transmission range of about 5 miles in semi-hilly terrain. Once you introduce mountains or trees, or even different weather patterns, that could drop to a quarter mile or less.

In perfectly ideal situations (midwest USA, for example), you could see range well over 10-15 miles.

 

[Bonnie6G]

Is that about 25w? I'm not super familiar with GRMS radios by model. My comms training is military, so I'm used to bigger equipment.

If that's about 25w, factoring in the stubby, you will likely get a SOLID transmission range of about 5 miles in semi-hilly terrain. Once you introduce mountains or trees, or even different weather patterns, that could drop to a quarter mile or less.

In perfectly ideal situations (midwest USA, for example), you could see range well over 10-15 miles.

Thanks for the numbers here. What about a 50w system. Could you provide some rough distances for the same as you describe above for comparison?

 

[Theherofails]

Thanks for the numbers here. What about a 50w system. Could you provide some rough distances for the same as you describe above for comparison?

The real world answer is you will get about the same range as the 25w in all situations except wide open spaces. If you live someplace where you will spend a lot of time in flat, open areas or on hill tops, you could see ranges in the 10s of miles easily. In ideal circumstances, you could pick up (or be picked up by others) transmissions from 100s of miles away with a quality antenna. Nothing you can count on reliably, but the power is there if the atmosphere plays along. Radio waves are basically modern day magic. SO many variables go into what you hear and how you hear it. Your maximum range is also dictated on the equipment at the receiving side as well, which is generally the cheapest Amazon parts available for most people.

In hilly, mountainous terrain is where the higher power really helps though. You'll be able to blast through the interference caused by radio waves reflecting off the terrain and your transmission will be much clearer for the receiving end. What you receive back is a function of the quality of your antenna and the transmitters total output power, and the quality of their antenna.

If you talk to the older folks who used HAM radio, you'll 100% hear stories about how when the weather is just right, they can pick up a numbers station in Germany or something.

I guess the short answer is you may not get a lot more range, but you will notice a quality improvement over lower power radios.

 

[Lazerus]

I use the midland MXT275 (15 watts - they have a 50 watt version as well) with the 6bd antenna fender mounted on my JL and have no problem hitting repeaters 40 - 50 miles away with a good line of sight. It has a swr of 1.03 to 1.07 across the band and transmits well with or without a good ground plane. For under $200 it's a good place to start.

 

[MileHighCitizen]

What about the extension cable that ties the antenna to the radio body? Does that come into play with regards to TX/RCPT or is that after the ground plane in the system?

The extension part does not come into play for tx/rx, the antenna grounds itself where it screws or attaches at its mount. so you measure antenna length from base of the mount, not from back of radio.

 

[Theherofails]

I use the midland MXT275 (15 watts - they have a 50 watt version as well) with the 6bd antenna fender mounted on my JL and have no problem hitting repeaters 40 - 50 miles away with a good line of sight. It has a swr of 1.03 to 1.07 across the band and transmits well with or without a good ground plane. For under $200 it's a good place to start.

I was debating mentioning repeaters.. Thats a whole other can of worms, but a really fun one IMO. Changes the entire dynamic when worried about range for these smaller civilian radios.

I think I'll save that for an audience who asks. Dont want to put everyone to sleep.

Its a cheap way to extend comms for your entire convoy though. Even the guys still using FRS.

 

[MileHighCitizen]

Thanks for the numbers here. What about a 50w system. Could you provide some rough distances for the same as you describe above for comparison?

Im working from the same military training as above, but you should see about 25 miles (flat terriain, good weather) of TX with 50w...but thats only if the other antenna is big enough to receive. the horizon is 18 miles, so beyond that its about having a big enough antenna to receive, until you start bouncing stuff off of the atmosphere (HF). All of the above is focused on TX, you will RX from around the world if the signal sent is strong enough to reach you

 

[Theherofails]

The extension part does not come into play for tx/rx, the antenna grounds itself where it screws or attaches at its mount. so you measure antenna length from base of the mount, not from back of radio.

This is a good point and we should define what a ground plane is just for people referencing this in the future.

Put simply, the signal from the antenna radiates downwards to a large extent, and the ground plane (AKA vehicle for a vehicle mounted antenna) is just a reflective surface to push the radio waves up and out instead of just bouncing off the earth and being largely scattered. While it does ground the antenna to the vehicle, its two different meanings of ground.. the ground plane is acting as the quite literal ground (earth) to reflect the signal.

This is one the major weaknesses for stubby antenna - they don't take advantage of a ground plane to assist with propagation.

Im working from the same military training as above, but you should see about 25 miles (flat terriain, good weather) of TX with 50w...but thats only if the other antenna is big enough to receive. the horizon is 18 miles, so beyond that its about having a big enough antenna to receive, until you start bouncing stuff off of the atmosphere (HF). All of the above is focused on TX, you will RX from around the world if the signal sent is strong enough to reach you

Good enough for the government is good enough for me!

 

[Lazerus]

Here's a good idea of what to expect. This guy is full of really good, no nonsense gmrs information. He's also very entertaining when debunking long held cb/ham/gmrs myths...his channel is always worth a watch.

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