Better mobile antenna setup w/HT?

[WRPV846]

I'm trying to figure out the most effective antenna setup with my Radioddity GM-30 for range.

First, I've already ordered a Nagoya 771G, and it should be here Monday. So, that makes a pretty easy addition to a Nagoya window mount. Easy peasy.

Would it be better to use some mount with NMO, and associated antenna? I guess I'll need a pigtail if I go that route.

Are "mounted" antennas more likely to have a higher dBi gain, in a general sense? The 771G has a 2.15 gain.

[Lscott]

58 minutes ago, WRPV846 said:

I'm trying to figure out the most effective antenna setup with my Radioddity GM-30 for range.

First, I've already ordered a Nagoya 771G, and it should be here Monday. So, that makes a pretty easy addition to a Nagoya window mount. Easy peasy.

Would it be better to use some mount with NMO, and associated antenna? I guess I'll need a pigtail if I go that route.

Are "mounted" antennas more likely to have a higher dBi gain, in a general sense? The 771G has a 2.15 gain.

That gain figure I’ll bet is 2.15dbi, or the gain over an isotopic antenna, which is a theoretical antenna that physically doesn’t exist. A simple dipole or 1/4 wave magnet mount has the same gain, 2.15dbi. Manufacturers like to quote gain figures in dbi, verses dbd - gain over a dipole, because it inflates the numbers making the specifications look more impressive. 
 

External antennas can, and many do, have high gains over a simple dipole or 1/4 wave type. There are a number to choose from. One thing seems to be true, the higher the gain the bigger (longer) it gets. I have a dual band high gain antenna on my Jeep. It’s nearly 5 feet tall as an example.

[wayoverthere]

14 hours ago, Lscott said:

That gain figure I’ll bet is 2.15dbi, or the gain over an isotopic antenna, which is a theoretical antenna that physically doesn’t exist. A simple dipole or 1/4 wave magnet mount has the same gain, 2.15dbi. Manufacturers like to quote gain figures in dbi, verses dbd - gain over a dipole, because it inflates the numbers making the specifications look more impressive. 
 

External antennas can, and many do, have high gains over a simple dipole or 1/4 wave type. There are a number to choose from. One thing seems to be true, the higher the gain the bigger (longer) it gets. I have a dual band high gain antenna on my Jeep. It’s nearly 5 feet tall as an example.

One reason for this is achieving the gain by "stacking" elements; the browning I've had good results with is a 5/8 over 5/8 wave for uhf. It claims 5.5dbd gain, and checks in around 33" long.

 

[lazarus1024]

14 hours ago, WRPV846 said:

I'm trying to figure out the most effective antenna setup with my Radioddity GM-30 for range.

First, I've already ordered a Nagoya 771G, and it should be here Monday. So, that makes a pretty easy addition to a Nagoya window mount. Easy peasy.

Would it be better to use some mount with NMO, and associated antenna? I guess I'll need a pigtail if I go that route.

Are "mounted" antennas more likely to have a higher dBi gain, in a general sense? The 771G has a 2.15 gain.

Unless I've missed something, the 771g is 2.6dBd, 4.75dBi. It is a 5/8 wave length antenna. The shorter 701g is a 1/4 wave and 2.15dBi. Its a similar gain and size to the UT-72 NMO mount antenna for use on a car. I am reasonably impressed with mine. I've tested a few antennas now. One of those tactical, foldable antennas (HYS in this case, Abbree also makes them), 771g, the rubber ducky that came with my Retevis H777, the tiny dual band whip that came on my UV-9g and a magic stick 5/8 extendable antenna.

I can't speak for exact gain as I don't have the equipment to test that. For SWR, the 771g was by far the best. I was clocking in around 1.7SWR. The HYS folded was about 2, unfolded it was about 3.5. The magic stick collapsed is about 1.9, but 3.1 extended. The rubber ducky from my H777 is about 2.6. The tiny dual band whip from my UV-9g is about 2.3.

 

For reception, its a tossup between the magic stick extended and the Nagoya 771g. I'd give maybe a slight edge of the Nagoya 771g. But for transmission, well again, I don't have a good way to test that without a lot more time and effort, but the much lower SWR of the Nagoya should mean much better Tx as you'd be losing about 20% due to standing wave reflections (assuming the radio isn't pulling power because of that much getting reflected back). They are both 5/8 wave length antennas with the magic stick extended, so it should be the same gain.

I have not tried a super stick. I'll probably get one at some point. I am a bit concerned about low temperature performance as it gets floppy in really cold weather...and well I've got enough excuses to want or need to use my radios in cold weather here in Maryland. I don't need an antenna that has erectile problems if the temp is dropping in to the 30s or colder. Which is a third of the year here. But its cheap enough, I'll try it. Probably needs to be tuned (cut to length) to maximize performance on GMRS.

 

Depends on how mobile you mean though. Even though they have the same theoretical gain, the UT-72 on the roof of my car has slightly better receive and transmit performance from what I can tell even over the 14' of RG-58 even though they are both supposedly 4.75dBi. Bonus points that the UT-72 measures 1.01SWR versus the 1.7 on my 771g. Probably that, plus a bit of gain in picking up reflections off the roof of my car is the deciding factor. Its a very small difference in performance though.

If you really want an even more effective setup, put a rooftop or attic high gain antenna up and run some LMR400 coax down to your HT and use an SMA to So239 adapter. I definitely get much better range performance on my UV-9g connected to my attic 6dBi antenna than my 771g from ground level (or even standing on the roof). Though that setup is very much not mobile.

If you stretch your definition of mobile, you could do a quicky setup with an extendable paint pole, tripod, a length of high quality coax and either a yagi antenna to go on the pole or a modest high gain antenna in the 6-7.2dBi range (HYS350-500MHz tunable antenna (6dBi) or Diamond XT50 (7.2dBi for UHF)). That is car mobile easily, or not too bad to backpack in if your intent was specifically to be carrying coms in to the backwoods for a setup (versus you are just bringing coms with you). Though at that point, you might as well get a battery, voltage converter and a mobile base station for a lot more transmit power too.

Sorry, probably way more information than you were looking for. The short story is, "yes, the Nagoya 771g is about the best you are likely to get ON the radio, but if you don't mind not portable or not very portable, then the sky is the limit".

 

IMHO, I'd take the antenna that came with your GM-30 with you with the 771g. The 771g will be a lot better, but there are plenty of times that is more than enough. I can get decent reception through most of my neighborhood, even with the terrain features I have half a mile from my house with the fairly short whip antenna that came on my UV-9g. And with an HT, you are usually going to be limited more by terrain than you will be by obstructions or line of sight distance limitations.

 

That said, I can hit a repeater 70 miles away not far from my house with the 771g on my UV-9g (the location is not too far from my house where I can hit the repeater. The repeater is of course far away). With the little whip 1/4 wave antenna I can't really hit said repeater (I can get a response, but my Tx isn't intelligible, and Rx is spotty).

[WRPV846]

Clearly, from reading Lazarus' post, I still have a bit of learning to do. Though a minor correction; the 771G is a 1/2 wave.

The idea is primarily just boosting my HT while driving; both in my SUV, and my RV when traveling in that. Would not be for deep hiking or the like.

FWIW, I am trying better to hit a repeater 61 miles from my house, as well as another one closer at 26.6 miles. I have the advantage of living on top of a high mesa, with both of those lower than me. I was surprised that the rinky dink antenna was able to...barely and intermittently, receive from the one 61 miles away.

[WyoJoe]

On 4/8/2022 at 10:23 AM, WRPV846 said:

The idea is primarily just boosting my HT while driving; both in my SUV, and my RV when traveling in that.

I'm not sure what kind of roof your RV has, but for the SUV, I'd recommend a mag-mount Nagoya UT-72G or something similar, with the appropriate adapter. If your RV has a steel roof, the mag-mount antenna would work on it, too. Otherwise, you'd need to figure something else out, or mount a steel plate to the roof on which you could place the antenna.

In addition to the mag-mount antenna, I'd recommend that you get a decent speaker mic for mobile use. This allows you to clip the radio to something where it will stay put, and to manipulate only the speaker mic when talking.