Mobile Antenna - Length, Gain, Range Questions

[WRWF513]

Hello everyone,

I've been experimenting with a few different antennas for my midland 50w micro mobile. I live in rural southern IL and I'm between NOAA weather stations and my closest repeater is over 60 miles away. Many mornings I can pick up the repeater but mid day it becomes more challenging. I'm assuming it has something to do with the atmosphere.

So I started looking for better antennas to increase the sensitivity and make the most out of the 50W radio.  I first tried the 3db ghost antenna with just a bit of success over stock. Then I went with Midland's MXTA26 6dB antenna and that improved things quite a bit. I still receive choppy NOAA weather and Occasional use of the repeater. I was hoping the new longer 7.5dB "Grand Vista" antenna would offer more improvements but I was a bit disappointed. It is actually slightly worse than the 6db. 

I have tried all of the antennas in the same mounting position, a bracket by the a-pillar / ditch light on my Jeep. Maybe a different location is needed to maximize the benefits of the longer antenna. I'm new to all of this, so any advice is appreciated. Thanks!

[marcspaz]

What year and model Jeep do you have? The 2018+ Wrangler and all current generation Gladiator have plastic corner caps between the hood and A pillar. You should have no less than 7 inches of metal in every direction. While there is metal under the plastic, it's recessed too far to help. So, you may just need to slide the mount closer to the front.

 

Also, not all antennas are created equal. One of the best antennas I have used to date, is the MXTA26.  I have had even better performance out of my Diamond NR-7900... though that is a very large/heavy antenna and may not be a good choice for a front/hood/lip mount. 

 

 

[WRWF513]

Thanks for the feedback. My Jeep is a 2017. The antenna is currently mounted and sticks out to the side of the hood. So this may just be a ground plane issue. I have a metal enclosure in my "trunk" area. Tomorrow I'm stripping the jeep down and I'll use my magnetic mount back there to see if it helps with performance but this area is only useful if the top is removed from the jeep. I don't really want to mound to the center of the hood and jeep roofs are not metal so that won't work . This might just be as good as it gets. If that's the case, I might return this antenna as the MXTA26 is the better choice. 

[Hoppyjr]

I agree ^ it could be a better ground may help the issue, but I wouldn’t expect anything to work too well if it sits lower than the roof.

Consider the new heavy duty Midland antenas, mounted back near the spare. There are some that extend above the roof, which should help significantly.

There are plenty of videos on YouTube, including review by Mark and different mounting options.

[marcspaz]

Moving it inside the roll bars will not help. Especially if the top of the metal enclosure is lower than the top of the tub.

 

Can you share a picture of how it's mounted now? It may just need a simple adjustment instead of a complete relocation. 

 

As you pointed out, the current location with the MXTA26 may be the optimal combination. When my top was down, I have put a mag mount on the metal brace above the speaker bar. That has worked very well for UHF, prior to my permanent mounts. 

[WRWF513]

So yesterday I was going on a Jeep ride event and had the top off.  Tried the  larger antenna with a mag mount on my security enclosed in the back.  The enclosed is even with the top of the tub.  Seemed like I might get a bit better performance with it.  Problem is that halfway to my first stop, my magnetic mount let go and the antenna fell over on the tailgate. Might try a tailgate mount before I give up on it. But so far the MXTA26 is just better all around.  Really bummed I spent $160 on this monstrosity.  Haha

[WRWF513]

Here is a picture of my current setup:

 

 

[marcspaz]

1 hour ago, WRWF513 said:

Here is a picture of my current setup:

 

 

 

I hate to say it, but that mount is not in a good place. In lamens terms, you're creating a short circuit for a large amount of your signal into the body.  The electro magnetic energy needs to have a minimum of a 1/4 wavelength of free space to work well (6 inches). A half wavelength (12 inches) or full wavelength (24 inches) would be even better.

 

I would recommend you get a Comet CP-5NMO mount and mount it on the hood, at lest 12 inches forward of the bottom edge of the A pillar. 14 or 15 inches away would be better.

 

Like this...

 

[bd348]

You could also get an adhesive metal disc and put a small mag mount further onto the hood.   Looking at the above photo with the high-lift on the hood, mine is mounted approximately half way between the antenna in the photo and the end of the high lift jack.  I.e. about an inch or two forward of the back edge of the hood, and in line with the edge of the plastic cowl piece.  This gives several inches of metal forward, left, and right, and I ran a grounded wire towards the wind shield for the backward direction, similar to a radial.  That wire may or may not make much of a difference.

Anyhow, a quarter wave mag mount on the adhesive disc works pretty well there, and it doesn't stick up too much to be annoying in the field of vision, it doesn't get knocked off by trees, and a quarter wave works pretty well in mountains with varying elevations.   To reach your distant repeater you probably want something with more gain.

Adhesive mag mount disc:

TAF DISC3.5

Larger size also available, but you need a flat surface for this, which turns out to be not so easy to find on a modern hood.

[WRWF513]

On 8/20/2023 at 8:49 PM, marcspaz said:

 

I hate to say it, but that mount is not in a good place. In lamens terms, you're creating a short circuit for a large amount of your signal into the body.  The electro magnetic energy needs to have a minimum of a 1/4 wavelength of free space to work well (6 inches). A half wavelength (12 inches) or full wavelength (24 inches) would be even better.

 

I would recommend you get a Comet CP-5NMO mount and mount it on the hood, at lest 12 inches forward of the bottom edge of the A pillar. 14 or 15 inches away would be better.

 

Like this...

 

Thanks for all the feedback. Unfortunately, I tried the suggested Comet Lip mount near the front fender of the jeep. and it did not provide any additional reception. For the record I'm still getting the best reception from my 6db MXTA26 antenna. Really disappointed with the 7.5db Grand Vista antenna from midland. I thought the length would give me better reception, not worse. 

Any other suggestions? Should I try running some kind of ground wire from the mount to the chassis?

 

 

[WRYF638]

21 hours ago, WRWF513 said:

Any other suggestions? Should I try running some kind of ground wire from the mount to the chassis?

From my days in CB radio (20 years ago), I recall that grounding the antenna and radio are critical to good transmission patterns, at least with standard mobile antennas. Grounding the antenna mount and radio also helps reduce RF interference from the vehicle. However, grounding will not change the incoming signal strength. One thing that will further improve reception is an RF signal booster. I have not seen any such products specifically designed for GMRS, but any UHF signal booster for 70cm/440mhz should do the job reasonably well.