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Mobile Antenna Tests and Final Decision


jas
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Hi all,

 

New here but have read a lot of you all’s posts. Great advice, thank you.

 

I'm an older pseudo-retired guy and with this COVID thing still going I have a lot of free time on hand. I forgot, and my GMRS license expired so I had to get a new one, new call sign and everything. Had the original since the mid '90s. Living in hurricane alley it was the best option then and still is. Whenever you have to leave your house behind, it’s convoy time.

 

So, after doing that, and replacing the HT radios (from the 90's) I decided to get a mobile radio.  I went with the midland MTX275 because of what I drive (see below). As most of you know it comes with a 1/4 wave 6-inch antenna, although I was surprised by the how thin the cable was, not like any coax I'd ever seen. As I found out, it's not a bad thing.

 

With lots of time on hand I decided to run some tests of the Midland antenna lineup.  The test was limited by my application. I'm driving a leased 2019 Lincoln Nautilus Black Label.  Look it up - NO holes allowed anywhere! It has a moon-roof, meaning I had to go magnetic and only have 14 inches of ground plane North/South, with the width of the roof for the sides. Mounted the radio under the driver's seat – remember, NO holes anywhere :). I live on an island in Florida. Lots of homes, 5-story condos and such = lost of interference and no high spots except for bridges.

 

So, for the tests I bought the MXTA12 magnetic mount, the MXTA25 Ghost and the MXTA26 "6DB" antennas. The antenna that comes with the MXT275 comes pre-wired, so I needed Midland’s bigger NMO mount for the new antennas. The mount is three times as big, very secure, rubber booted, and with a real coax cable. Off I went to test…

 

I’m a business analyst by profession, which means that when I analyze stuff I always start with worst case.  And that’s what I did here.  The tests were done by driving away on the mobile and transmitting, starting from the front of the house and then every ¼ mile. The receiver, a lowly HT was set up outside in the worst possible location and just high enough off the ground as to mimic a sitting position.  To record the test, I set the HT right in front of my iPad and set the iPad memo app to record. Each test took about 15 minutes.

 

The results? Reception on the HT in these worst of conditions, transmitting with the antenna included with the radio was all static at 3.5 miles and cut off completely at 3.75-miles. Had a lot of static at 2.5 miles when I drove by a 2-story small shopping center adjacent to a 4-story condo in the line of sight.  I went over a 25-foot-tall bridge at 3.25 miles where the transmission was perfectly clear.

 

With the MTXA25 Ghost antenna installed, the difference in the results were measured in feet (not good).  In the clear it is clearer, but it has a lot of static in the same places as the little 6-inch included antenna. It is possible that in a best-case scenario, the opposite of what I did, it will outshine the ¼ wave antenna. In my opinion it’s not worth the extra money for that cable and antenna combo. The difference is that small. 

 

The MXTA26 ran away with the test. I believe it is a 5/8 wave antenna and it’s all of 32-inches tall and so I must stop when I get home and take it off to go in the garage (raining?). Not a reasonable thing for everyday use. I quit that test at 5-miles, it didn’t cut off like the other two, just unintelligible static. It outperformed the two other antennas both in clarity and distance by a mile. That’s a big number when trying to hit a HT in the worst conditions distance percentage wise. 

 

I did other tests, 100-mile loops with all three antennas, that was a reception test, not a transmit one. The MXTA26 still won the day. The other two were about the same.

 

After this test, and for every-day use I just ordered a Laird ¼ wave antenna, the QWB450. Only reason I did that is to keep the MXTA12 magnetic mount so I can swap between the ¼ wave and the MXTA26 when needed. I have no use for the MTXA25 Ghost.

 

Well, that’s it for me. Hope this was helpful.

 

All the best,

 

JAS

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Hello JAS. It is wonderful to learn of such differences contrasted in the same environment. I have recently contrasted hand-held radios in my environment. Write-up to come.

 

By the way, I have been quite pleased with the MXTA26 and have the same issue as you when entering the garage. I do leave the NMO mag-mount on the vehicle, just step up and unscrew the antenna and the throw it in the back seat. Admittedly about a dozen times now I have forgotten. Thanks the spring base it has survived each incident.

 

Thanks for the nice write up.

 

 

Michael

WRHS965

KE8PLM

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JAS,

thanks for sharing!  In a far less organized way, I have been making some comparisons of the same.  I have been using the Ghost "pepper shaker" as an NMO place keeper when off-road in brush and when not planning to use the radio.  The 6db whip gets screwed on when I plan to use the radio and need more distance.

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It's a shame to hear the ghost is that bad.

 

I have the antenna it replaced, (I forget the mxta number), ~12" base loaded whip, and it does pretty well shoved up in my attic as a base antenna, and doesn't need much clearance on the truck, even on the roof.

It's not that the MTXA25 is that bad. It's just that in a worse case test the difference between the antenna that came with the radio and the ghost is not enough to justify the cost of the new cable and the cost of the antenna itself. And as I mentioned, in best conditions the ghost might outperform the 1/4 wave factory antenna.  I don't have that information.

 

If there is one thing I've learned about UHF so far is that when transmitting in all kinds of different situations, going up in elevation beats everything else.

 

I remember using AM radios on boats back in the day. Some special days we could transmit and receive over 100 miles (all over water). UHF is clearly a different animal.  Line of sight is basically the limit.  Even an extra foot or two in antenna height, as was the case in the test with the MXTA26, and maybe coupled with a bit of extra power from the antenna's directionality could account for extending the range by another 20% or so.....

 

Best,

 

JAS

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It's a shame to hear the ghost is that bad.

 

I have the antenna it replaced, (I forget the mxta number), ~12" base loaded whip, and it does pretty well shoved up in my attic as a base antenna, and doesn't need much clearance on the truck, even on the roof.

I didn't mean to say my Ghost is bad.  It is short and strong, the attributes I wanted it for.  My mounting is at the hood-fender lip and near the "a" pillar.  Antenna propagation is changed based on a lot of factors.  In my location much of the antenna is shaded by parts of the vehicle. Antenna height counts for a lot.  I also "think" which is different from know... that at unity gain a coiled 1/4 wave antenna can't perform as well as a 1/4 wave straight whip (1/4 wave and gain for purpose of example).  I like the Ghost, it has low observability, is relatively immune to branches and other things and hopefully will be up to the task of vehicle to vehicle communication in a "convoy" type situation.  The ghost antenna may be perfect for many applications.  

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Hi All,

 

This is an addendum to the antenna tests, with a not too unexpected twist, with new information for the twist not being available for the tests I performed and posted previously. A point to make is that I designed the test for worst case conditions and in retrospect, that is not the case most of the time when going mobile.

 

In subsequent posts on this thread, I made a response to another post within the thread which I will repeat here. This had to do with the performance of the Midland MXTA25 “ghost”. It went like this:

 

“……It's not that the MTXA25 is that bad. It's just that in a worse case test the difference between the antenna that came with the radio and the ghost is not enough to justify the cost of the new cable and the cost of the antenna itself. And as I mentioned, in best conditions the ghost might outperform the 1/4 wave factory antenna.  I don't have that information…..”

 

Based on my tests I decided to order a Laird ¼ wave antenna to use as a primary. This way I could switch antennas between it and my 6dB MXTA26 antenna. At first it seemed to work fine. But that changed.

 

Over the course of a month and a few hundred miles in all conditions, during which I switched antennas multiple times for testing, I’ve come to the conclusion that in normal mobile usage the MXTA25 “Ghost” antenna is much superior to the ¼ wave Laird.

 

It vastly outperforms the ¼ wave antenna in reception (I don’t know why just yet) but also does on transmissions. This is under normal everyday driving in all sorts of situations, and of note, with distant repeaters. The transmission side is easier to understand if the 3dB gain claim for the MXT25 is to be believed. At this point it sure seems  to be a true claim. 

 

The Midland mag mount comes with a 6 meter (long!) RG58/a/u cable. If using the 0dB gain ¼ wave antenna, the math says that in that setup the MXT275 radio is putting out just 7 watts or so.  With a 3dB gain on the Ghost that becomes 14 watts (theoretically).

 

It sure seems to be playing out that way. Only on worst case (my original test) did it not.

 

So, off came the ¼ wave Laird. I am now using the MXTA25 as my standard antenna. I still have not figured out why the reception would be so much better with the MXTA25 but I’m working on that.

 

Thanks all!

 

Best,

 

JAS

WRKP245

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What difference would the longer 6 meter cable for the 3/4" hard mount make in this equation?

I apologize, The 3 meters up above was a typo and has been corrected. I meant 6 meters. My calculation results were based on 6 meters and are accurate for that length. If the hard mount uses the same RG58/a/u cable then the results should be the same.

 

Best,

 

JAS

WRKP245

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