Midland MXT400

unsung

Active member
I just found out that the trail ride I am on this weekend switched to GMRS from CB. Well, I have HAM and CB. So I just paid the $70 which I thought was being reduced and I've been told will be approved overnight but I'm not holding my breath. I'm not the type to go cheap so I will probably grab this radio https://midlandusa.com/product/mxt400-micromobile-2-way-radio/ and will need an antenna and mount and cable. Midland links this antenna with the radio https://midlandusa.com/product/micromobile-mxta26-6db-gain-whip-antenna/

I am not positive on the appropriate cable for in between. I used this one for my HAM based on the recommendation here. https://www.hamradio.com/detail.cfm?pid=H0-001464 I was thinking of running it (or similar with correct connectors) out the other side of the rear hatch on my Land Cruiser.

Maybe this one?


I know NOTHING about GMRS, never have used it. Looking for any and all good advice, thanks.
 
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jadmt

ignore button user
my buddy has the mxt400 and I have the lowly mxt105 and we can talk to each other miles away. So much nice than a cb.
 
Right style I don't know what size hole you are mounting in and what size hole that requires. Diamond Larsen and Comet make that style mount for different hole sizes.
 

DaveInDenver

Middle Income Semi-Redneck
FWIW don't necessarily limit yourself to a couple of antenna choices.

There's nothing magical about GMRS. It's UHF still and just slightly higher than the 70cm ham band so you might even have an old ham antenna that will work. Some of them even have enough bandwidth to cover both the upper voice end of the ham band and GMRS.


For example, the specs on this one are similar to the one you link - 5dB of gain with an open coil in the middle (probably collinear elements). It's a few inches longer and lacks a spring but is $20 less. You might not need the spring if the base is low enough not to be subject to catching stuff. On a roof having a spring is more important than lower on a lip or fender.


If I was to guess the Midland base looks similar to the Laird bases, which are pretty nice. For $50 I'd personally get a real Laird, like the B450CNS. It's got a spring at the base although the coil is closed and not open. Similar gain (5 dB) and length (31"). This particular one is also ground plane independent, since you mentioned on the lip of a hatch.


If you want one that's black and not chrome it's $60, though.
 
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unsung

Active member
My mount isn’t on the bumper but will be one of these that I’ll modify. I’m going to try a handheld for this ride and come back to this after since I’ll never get everything installed in time.

 

ebg18t

Adventurer
@DaveInDenver - Can you provide some clarity on how the Laird 1/2 wave Antenna I linked above (we have been using for a bit) would compare to the Laird 5/8 over 5/8 linked below (BB4505CN) or even a longer 1/2 wave from Laird. In looking at the Laird site the vertical beam width is much narrower on the 5/8 over 5/8 (28 deg vs 110 deg), so if I understand right it may travel further in flat terrain but not as broad as the 1/2 wave in rolling terrain?


We have been happy with the short, 10.5" 1/2 wave Laird for low speed use and has worked well in fairly wooded terrain. But we have been doing a tad more highway driving and I notice that both our vehicles are having an increased amount of clarity issues and sound increasing/decreasing at highways speeds and got me thinking about a different antenna setup for road use.
 

DaveInDenver

Middle Income Semi-Redneck
@DaveInDenver - Can you provide some clarity on how the Laird 1/2 wave Antenna I linked above (we have been using for a bit) would compare to the Laird 5/8 over 5/8 linked below (BB4505CN) or even a longer 1/2 wave from Laird. In looking at the Laird site the vertical beam width is much narrower on the 5/8 over 5/8 (28 deg vs 110 deg), so if I understand right it may travel further in flat terrain but not as broad as the 1/2 wave in rolling terrain?

We have been happy with the short, 10.5" 1/2 wave Laird for low speed use and has worked well in fairly wooded terrain. But we have been doing a tad more highway driving and I notice that both our vehicles are having an increased amount of clarity issues and sound increasing/decreasing at highways speeds and got me thinking about a different antenna setup for road use.
You've hinted at the difference - beamwidth and directivity. As you increase gain the beamwidth narrows. In the case of a vertical antenna like that means you want to see the main lobe(s) of energy flatten towards the horizon.

This is a very simple simulation run comparing a generic 1/2λ (dashed black reference trace) whip to a stacked 5/8λ collinear whip with a 3/8λ stub coupling (solid red line).

It was run in freespace (e.g. no ground) and with perfect length elements. IOW, don't read too much into this as an example of real world characteristics or actual gain you should expect, just trying to put a visual to what I'm saying. Oh, also, the pattern isn't perfectly symmetrical due to the models I built and the way the antenna simulation tool works (it's called NEC).

But beamwidth is defined as the region bounded between the points where the radiated power falls 3 dB below the peak point. So I've put the blue (on the collinear) and green (on the 1/2λ) bars showing those approximate points.

Since the chart uses 0 dB as the outer ring the blue region should be roughly where the red trace intersects the -3 dB ring. Likewise the peak point on the reference is around -2 dB so the green bars indicate the point where the dashed line intersects with the -5 dB ring.

So the 110° beamwidth compared to 28° I hope makes sense, that being the angle between the pairs of bars, very roughly. In theory. You know, sort of.

halfwave-vs-58wavecollinear_withbars.png

Now the questions are (1) what about real world performance and (b) does it make any difference. That's kind of a contextual answer. When you put each of these antennas on your truck they are not going to look like the ideal patterns.

Simply changing the run from free space to putting the antennas over average ground changes things (these are very simple models so the patterns I get don't necessarily match exactly what might be published in references or marketing material). The dashed is still the 1/2λ and solid red collinear. Beamwidth measurement is changed obviously due to the ground plane. You get a gain improvement, though.

halfwave-vs-58wavecollinear_avgground.png

On your truck this is probably a pretty fair indication of what you can expect I'd think. But consider that UHF is primarily line of sight. Even with 5 watts and a 1/4λ on your roof it's entirely possible in clear topology you'd be limited by the curve of the Earth and not enough antenna height more than signal strength.

The problem comes down to what's blocking you. With landscape and buildings increasing signal strength isn't going to really help. Rock and steel are outstanding at absorbing and reflecting energy. So if 5 watts doesn't do it 50 or 500 is only going to heat the rock more and create additional multipath issues. Getting a clear view is your solution.

Now with vegetation it's a little different. Leaves and brush absorb RF energy but not as well as rocks. Think of it like holding up a granite tile verses a cotton shirt to a light bulb. The granite is completely opaque while fabric isn't. So focusing more RF energy on the horizon in trees might help.

But also look at the patterns and think about your aspects to other stations. To get that extra couple of dB in absolute peak gain you really do concentrate your energy. If a station is maybe even just 15° higher than the middle of the main lobe you lose around 8dB of gain and at 45° it's down 20 dB, completely deaf. And I doubt the lobe at 90° is of much help. The 1/2λ is obviously more forgiving.

And think about being mobile you antenna may not be particularly rigid and the aspect is constantly changing as it flops around in the wind. That means you might hear the radio constantly going from S9+ full quiet so barely audible static (this is called signal fade). That's why you see high gain antennas like collinears built into rigid fiberglass or plastic tubes (called radomes) so they are always vertical.

FWIW, I also ran a 1/2λ (reference dashed) compared to a 1/4λ (solid red) using the same characteristics for feedpoint and ground as in the second graph just to give a feel for how gain and coverage are interconnected. There's 2 dB of difference in absolute gain just there. So from a 1/4λ to a collinear is around 4 to 5 dB of difference, which is certainly significant. That's equivalent to roughly 2.5 to 3 times more transmitter power.

There's trade-offs to deciding on which criteria to prioritize, it's not a simple decision. A lot of people, hams anyway, keep two antennas in their truck. A low gain one that's low profile so it doesn't hit overhangs and doesn't fade in-and-out. And a high gain in case you need it.

halfwave-vs-quarterwave.png
 
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ebg18t

Adventurer
You've hinted at the difference - beamwidth and directivity. As you increase gain the beamwidth narrows. In the case of a vertical antenna like that means you want to see the main lobe(s) of energy flatten towards the horizon.

This is a very simple simulation run comparing a generic 1/2λ (dashed black reference trace) whip to a stacked 5/8λ collinear whip with a 3/8λ stub coupling (solid red line).

It was run in freespace (e.g. no ground) and with perfect length elements. IOW, don't read too much into this as an example of real world characteristics or actual gain you should expect, just trying to put a visual to what I'm saying. Oh, also, the pattern isn't perfectly symmetrical due to the models I built and the way the antenna simulation tool works (it's called NEC).

But beamwidth is defined as the region bounded between the points where the radiated power falls 3 dB below the peak point. So I've put the blue (on the collinear) and green (on the 1/2λ) bars showing those approximate points.

Since the chart uses 0 dB as the outer ring the blue region should be roughly where the red trace intersects the -3 dB ring. Likewise the peak point on the reference is around -2 dB so the green bars indicate the point where the dashed line intersects with the -5 dB ring.

So the 110° beamwidth compared to 28° I hope makes sense, that being the angle between the pairs of bars, very roughly. In theory. You know, sort of.

View attachment 676018

Now the questions are (1) what about real world performance and (b) does it make any difference. That's kind of a contextual answer. When you put each of these antennas on your truck they are not going to look like the ideal patterns.

Simply changing the run from free space to putting the antennas over average ground changes things (these are very simple models so the patterns I get don't necessarily match exactly what might be published in references or marketing material). The dashed is still the 1/2λ and solid red collinear. Beamwidth measurement is changed obviously due to the ground plane. You get a gain improvement, though.

View attachment 676056

On your truck this is probably a pretty fair indication of what you can expect I'd think. But consider that UHF is primarily line of sight. Even with 5 watts and a 1/4λ on your roof it's entirely possible in clear topology you'd be limited by the curve of the Earth and not enough antenna height more than signal strength.

The problem comes down to what's blocking you. With landscape and buildings increasing signal strength isn't going to really help. Rock and steel are outstanding at absorbing and reflecting energy. So if 5 watts doesn't do it 50 or 500 is only going to heat the rock more and create additional multipath issues. Getting a clear view is your solution.

Now with vegetation it's a little different. Leaves and brush absorb RF energy but not as well as rocks. Think of it like holding up a granite tile verses a cotton shirt to a light bulb. The granite is completely opaque while fabric isn't. So focusing more RF energy on the horizon in trees might help.

But also look at the patterns and think about your aspects to other stations. To get that extra couple of dB in absolute peak gain you really do concentrate your energy. If a station is maybe even just 15° higher than the middle of the main lobe you lose around 8dB of gain and at 45° it's down 20 dB, completely deaf. And I doubt the lobe at 90° is of much help. The 1/2λ is obviously more forgiving.

And think about being mobile you antenna may not be particularly rigid and the aspect is constantly changing as it flops around in the wind. That means you might hear the radio constantly going from S9+ full quiet so barely audible static (this is called signal fade). That's why you see high gain antennas like collinears built into rigid fiberglass or plastic tubes (called radomes) so they are always vertical.

FWIW, I also ran a 1/2λ (reference dashed) compared to a 1/4λ (solid red) using the same characteristics for feedpoint and ground as in the second graph just to give a feel for how gain and coverage are interconnected. There's 2 dB of difference in absolute gain just there. So from a 1/4λ to a collinear is around 4 to 5 dB of difference, which is certainly significant. That's equivalent to roughly 2.5 to 3 times more transmitter power.

There's trade-offs to deciding on which criteria to prioritize, it's not a simple decision. A lot of people, hams anyway, keep two antennas in their truck. A low gain one that's low profile so it doesn't hit overhangs and doesn't fade in-and-out. And a high gain in case you need it.

View attachment 676055

Wow. Thank you so much for the explanation. I need to review a few more times to unpack this completely.
 
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It's UHF don't over think it. It's line of sight. Just get as much antenna gain as you can. Tall trees make great reflectors and cause lot of multi path signals. I use to conduct vhf foxhunts. Meanest trick I ever saw was a base station antenna hauled half way up a tree in the state forest. Far away you could get a great direction reading. Close in had signals coming from all directions.
 

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