Jump to content
  • 0

Dual band and GMRS antenna in one?


WRTZ750
 Share

Question

14 answers to this question

Recommended Posts

  • 0
1 hour ago, WRTZ750 said:

Is there such a thing for mobile radios?  I know hams have the dual band antenna but do they have an antenna that covers 2m, 70cm AND GMRS?

As @BoxCar mentioned it's yes and no. Some antennas might work just fine even if the manufacture's specifications don't cover the frequency range. You'll need to test it.

I have an old, like 20 years, dual band Comet antenna that works great on both Ham bands, MURS and GMRS. Unfortunately they don't make it any more. I had purchased two at the time. One I used strictly indoors, never saw the outside and looks like new. If the one I have on the vehicle ever fails completely or gets destroyed I have a back up.

I did an SWR scan using a RigExpert AA-1000 antenna analyzer.

https://rigexpert.com/products/antenna-analyzers/aa-1000/

I was curious to see how it performed verses the manufacturer's spec's. See the attached files. The scans are the antenna as mounted on my old Jeep's roof rack cross bar.

SWR Ham 70cm and GMRS.jpg

SWR Ham 2M and MURS.jpg

CA-2x4MB Manual.pdf

Link to comment
Share on other sites

  • 0

Yes...some antennas are more forgiving (wider range covered) than others. One example is the comet 2x4sr. Covers 2m, MURS, 70cm, and GMRS. On the downside, it's ~36" long.

Still available, as far as I know, in both nmo and uhf bases. (I'm partial to nmo for its wide availability, so I can swap whips at will.)

Link to comment
Share on other sites

  • 0

I use the Comet 2x4SR. I have one in UHF and one in NMO.

 

It works great in 2M, MURS, 70CM, and it has a 2.6:1 SWR or better on all GMRS channels, including the repeater inputs.  It has about 4dB of 'real' gain on the GMRS channels.

 

It is a compromise across the board to have it all on one antenna. 

 

UHF 

https://www.hamradio.com/detail.cfm?pid=H0-001424

 

NMO

https://www.hamradio.com/detail.cfm?pid=H0-011146

 

I also have a Comet M-24m that I use when clearance is an issue.  It woks better on GMRS than the Ham bands. But, as I mentioned, there is going to be compromise. 

 

 

Link to comment
Share on other sites

  • 0
10 minutes ago, marcspaz said:

I use the Comet 2x4SR. I have one in UHF and one in NMO.

 

It works great in 2M, MURS, 70CM, and it has a 2.6:1 SWR or better on all GMRS channels, including the repeater inputs.  It has about 4dB of 'real' gain on the GMRS channels.

It's 2.6:1 on GMRS? That's high. I'm guessing you mean 1.6:1.

The antenna is a good wide band design, but it's a bit sensitive to the mounting location. Being a 5/8 wave it needs a good ground plane.

Link to comment
Share on other sites

  • 0
Just now, Lscott said:

It's 2.6:1 on GMRS? That's high. I'm guessing you mean 1.6:1.

The antenna is a good wide band design, but it's a bit sensitive to the mounting location. Being a 5/8 wave it needs a good ground plane.

 

No... it's 2.6:1 on the 467mhz channel.  I don't see a 1.6 on any frequency with that antenna. I think the best I get is on 2m, it's 1.7.

 

The advertised range stops at 465mhz and it's used in very limited circumstances. So, I'm not too worried about it. The UHF and the NMO are mounted in very different locations, but have near identical performance.  I also mo Ed them to a few different vehicles with the mag mount and there was very similar performance. 

 

As I mentioned, it's it's compromise to use it, but I don't worry about SWR until it's at 3:1. Then I consider tuning are replacing the antenna. 

Link to comment
Share on other sites

  • 0
42 minutes ago, Lscott said:

It's 2.6:1 on GMRS? That's high. I'm guessing you mean 1.6:1.

The antenna is a good wide band design, but it's a bit sensitive to the mounting location. Being a 5/8 wave it needs a good ground plane.

I'll have to recheck mine, but I want to say it was 1.4 or less everywhere I tested. I have the spring kit, and it's mag mounted dead center on the roof of a single cab compact truck, so decent ground plane.

I also remembered I have a small diamond (nr72b, maybe?) that's advertised as dual band...grabbed it for it's small size (trying to to find a better performing dual band/limited clearance option than the Comet SBB1), and it's near 1:1 on uhf, and maybe 1.3 on gmrs. I say "advertised", because it's like 2.5-3 on 2m on the truck, but decent on a piece of sheet metal indoors. Haven't gone back out to see if it likes an "edge" in the ground plane like the compactennas apparently like, still waiting for a break from triple digit highs (they're saying 115 on Tuesday 🥵)

Link to comment
Share on other sites

  • 0

Thanks for all the good antenna options.  I think I'll stick with just the GMRS antenna like that Midland one with the 6db gain for now, I can't recall the model number.  Once I get my HAM license I'll think about these dual band antennas you mention.  Then again, I might be able to listen/monitor more frequencies with the dual band antennas as opposed to the Midland GMRS mobile antenna?

Link to comment
Share on other sites

  • 0
58 minutes ago, WRTZ750 said:

Thanks for all the good antenna options.  I think I'll stick with just the GMRS antenna like that Midland one with the 6db gain for now, I can't recall the model number.  Once I get my HAM license I'll think about these dual band antennas you mention.  Then again, I might be able to listen/monitor more frequencies with the dual band antennas as opposed to the Midland GMRS mobile antenna?

For receive, the main criteria is length -- longer antenna "captures" more input signal; tuning for frequency/SWR is less critical unless you are really into weak-signal work.

Transmit, OTOH...

Link to comment
Share on other sites

  • 0
2 hours ago, WRTZ750 said:

Thanks for all the good antenna options.  I think I'll stick with just the GMRS antenna like that Midland one with the 6db gain for now, I can't recall the model number.  ?

Mxta26. I wish they still sold their 3db whip rather than the ghost, that worked well without being too tall.

1 hour ago, BoxCar said:

The best antennas for bandwidth are the ones designed for single band, commercial use. Dual  and tri-band antennas are all compromises made to tweak the antenna to work acceptably.

This. I've had very good results out of a single band Laird for 70cm.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Answer this question...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use and Guidelines.