Wide band antenna for 2m 440 and GMRS

[blastco2]

Looking for a base antenna with some gain, that will cover ham and gmrs. I really dont want to buy or install 2 antennas on my 2 seperate base stations. I have commercial radios for gmrs and ham. So far best i have found is really good on ham and 2.8:1 on gmrs. Any advice that you can give will be greatly appreciated. Im using a comet ca-2x4 for mobile ops and it works great. Tried mounting one for a base and got bad results. Is there an antenna that will cover ham and gmrs with a reasonable swr???

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[cmdrwill]

Simple answer, NO.

And it looks like you forgot the other half of the antenna in your test.

 

[ko6jw_2]

Getting high gain and bandwidth is very difficult to achieve. The Comet you mentioned could be used as a base with the right ground plane. Check out this website:

ALPHA~NODE® HUB - Home

They make a variety of base mounting hubs that can then be equipped with ground radials in various configurations. It's a DIY thing. I would suggest a hub with an NMO or UHF base (depending on how the Comet is made) with four radials cut for 2 meters as a start. It won't be cheap and you will have to experiment, but it can probably be made to work.

Hustler also sells base mounts with radials for converting mobile antennas to base use.

 

[bharvey2]

An antenna that meets all of your requirements may be tough to come by. Keep in mind, the 70cm band is already a broad chunk of Ham spectrum at 30MHZ and trying to get GMRS would add almost 18MHZ more. Also, you want to keep 2M in the mix as well.

Discone and log periodic antennas are both broadband antennas but have their drawbacks: no gain and directional respectively. Something to consider: a 1/4 wave dedicated GMRS ground plane would be pretty small. If you're handy with tools, you could try building something like one of the Arrow J-Pole or 1/4 wave antennas and adjust the lengths until you can come up with a happy medium in the SWR department. I'd guess though that not too much happiness would come out of it.

One more item to consider: I don't think you could find an easy way to tie a HAM radio and GMRS radio to the same antenna and run them concurrently. An antenna switch might work but I've never seen a diplexer that can split bands so close together. - Perhaps something in the commercial world might exist. Others may have more experience with what you are trying to accomplish. I know I finally went with two antennas.

 

[blastco2]

Simple answer, NO.

And it looks like you forgot the other half of the antenna in your test.

And what would be the other half? A ground plane mount/kit? If that is what you are crypticly refereing to, then, no i did not forget half of the antenna....

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[blastco2]

Getting high gain and bandwidth is very difficult to achieve. The Comet you mentioned could be used as a base with the right ground plane. Check out this website:

ALPHA~NODE® HUB - Home

They make a variety of base mounting hubs that can then be equipped with ground radials in various configurations. It's a DIY thing. I would suggest a hub with an NMO or UHF base (depending on how the Comet is made) with four radials cut for 2 meters as a start. It won't be cheap and you will have to experiment, but it can probably be made to work.

Hustler also sells base mounts with radials for converting mobile antennas to base use.

Thanks, for the reply. Modest gain would be enough. Make up for coax loss... What you've said, is the same as i have found with my messing about with antennas. That hub mount looks good but, too much money. For the hub and the comet antenna, cost is going to be 150ish. For that, I can buy a nice length of lmr400 and material for 3-4 osj's to experiment with. I think that is the direction I will go next.

An antenna that meets all of your requirements may be tough to come by. Keep in mind, the 70cm band is already a broad chunk of Ham spectrum at 30MHZ and trying to get GMRS would add almost 18MHZ more. Also, you want to keep 2M in the mix as well.

Discone and log periodic antennas are both broadband antennas but have their drawbacks: no gain and directional respectively. Something to consider: a 1/4 wave dedicated GMRS ground plane would be pretty small. If you're handy with tools, you could try building something like one of the Arrow J-Pole or 1/4 wave antennas and adjust the lengths until you can come up with a happy medium in the SWR department. I'd guess though that not too much happiness would come out of it.

One more item to consider: I don't think you could find an easy way to tie a HAM radio and GMRS radio to the same antenna and run them concurrently. An antenna switch might work but I've never seen a diplexer that can split bands so close together. - Perhaps something in the commercial world might exist. Others may have more experience with what you are trying to accomplish. I know I finally went with two antennas.

Looking at arrow's site, in the parts list, all the dimensions for the gmrs and ham versions are listed. Thinking I'll cut one for the middle and see how it tunes. If it is unacceptable, i can still shorten it for gmrs.

I have read that thicker elements will yield wider bandwidth. Wondering if an osj could be built with 1/2" round bar, instead of the standard 3/8"?? Also would the spacing of the rods need to be changed?? Enough to make up for the extra dia, or wider still?? I guess that is what experimenting is for.... aluminium angle is inexpensive and I have 4' of angle and 10'x3/8" and 10'x1/2" aluminium round bars.... got all the stuff to build/experiment, just need some ambition....

Thanks for all the replies... good and helpful info!

If I dont post a follow up of my findings, feel free to prompt me with a post or pm or both....

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[Project25_MASTR]

I've had a love hate affair with the Comet mentioned above. Too stiff for my purposes (have actually ripped a mount out of the roof before). I went to a PCTEL wide band knob (unity gain, 430-480 MHz) on UHF and a simple 1/4 wave VHF whip to get the bandwidth (since I was already running dual radios).

Best setup I've found so far is a hybrid setup consisting of a DB222 and DB408D on a common mast. Still requires dual feedlines or a a diplexer on the tower though.


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[blastco2]

I've had a love hate affair with the Comet mentioned above. Too stiff for my purposes (have actually ripped a mount out of the roof before). I went to a PCTEL wide band knob (unity gain, 430-480 MHz) on UHF and a simple 1/4 wave VHF whip to get the bandwidth (since I was already running dual radios).

Best setup I've found so far is a hybrid setup consisting of a DB222 and DB408D on a common mast. Still requires dual feedlines or a a diplexer on the tower though.


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I have 2 of them mounted on dodge pickups, fender mounts. Real good luck so far. There is a optional lower section, with a spring, for the comet. As tall as my pickups are, I wouldn't dare try to do a roof mount. Maybe a headache rack with the sprung antenna would be durable enough and give a better pattern than a fender mount. However, trying to combine a cab and bed into a single ground plane can be more trouble than it is worth. ...

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[bharvey2]

The arrow website has drawings that are detailed enough to use for construction drawings. However you might look online for J-Pole antenna calculators to help point you in the right direction. I recall that they have drawings for a ground plane as well and it has to vertical elements. I don't know if spacing is critical on a ground plane. Maybe you could drill and thread the top ends of the vertical elements and use long screws for length adjustment?

 

[Project25_MASTR]

I have 2 of them mounted on dodge pickups, fender mounts. Real good luck so far. There is a optional lower section, with a spring, for the comet. As tall as my pickups are, I wouldn't dare try to do a roof mount. Maybe a headache rack with the sprung antenna would be durable enough and give a better pattern than a fender mount. However, trying to combine a cab and bed into a single ground plane can be more trouble than it is worth. ...

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They've only had that spring option for about a year now. I tore the mount out about 2.5 years ago. I believe the spring was a solution of they realized they were facing lawsuits for vehicle damage for offering a "Search and Rescue" antenna that couldn't handle the terrain without doing damage.

I've got the two I had still. Hey work, I just don't have a need for them since I can't practically roof mount them.


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[krokus]

They've only had that spring option for about a year now. I tore the mount out about 2.5 years ago. I believe the spring was a solution of they realized they were facing lawsuits for vehicle damage for offering a "Search and Rescue" antenna that couldn't handle the terrain without doing damage.

I've got the two I had still. Hey work, I just don't have a need for them since I can't practically roof mount them.


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The roof of my Jeep was damaged, while I had one of these antennas mounted. I ended up installing a fender washer on the inside portion of the NMO, to spread out the physical stress.

Now that they have the spring version, and I liked the performance, I will give one of those serious consideration.

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[blastco2]

The roof of my Jeep was damaged, while I had one of these antennas mounted. I ended up installing a fender washer on the inside portion of the NMO, to spread out the physical stress.

Now that they have the spring version, and I liked the performance, I will give one of those serious consideration.

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You probably know this but, if you don't or for others following this.
The spring option must be purchased seperate from the antenna then user installed. It is about 25 plus frt. I have not tried it, only seen the adds and pictures. I have not found the antenna for sale with the spring installed. It may be, but i havent found it.

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[blastco2]

The arrow website has drawings that are detailed enough to use for construction drawings. However you might look online for J-Pole antenna calculators to help point you in the right direction. I recall that they have drawings for a ground plane as well and it has to vertical elements. I don't know if spacing is critical on a ground plane. Maybe you could drill and thread the top ends of the vertical elements and use long screws for length adjustment?

Now that is a dang good idea! Thank you! i just happen to know a couple of fellows that have a lathe and mill in their garages. Bet i can get it drilled/bored for a six pack. Three #10 machine screws and jam nuts, stainlesss of course. This could be fun and interesting......

Just thinking and typeing....about building an osj with half inch rod (3/8 is usual/standard). Looking for more bandwidth.
Fact, spacing of the rods is important. So, to maintain the same spacing, the middle hole (short element) should be 1/8" to the right of the #1/ hole (driven element) then the third hole should be 1/8" further from the second hole..... that should maintain the same spacing. But, really, just how critical is the spacing? When assembled, the elements are not perfectly straight, the spacing, at the tips, is varied from antenna to antenna. Hmm... questions questions, try not to over or under think this. Maybe holes 2 and 3 should be slotted? I think I'm going to need one of them fancy gagets that tells you what the antenna is good for....what is it called, analyzer?

Okay, that is enough rambling for one post. I am getting curious and a little interested/excited. Think I'll wonder up to my shop, aka, redneck headquarters, and let the tinkering begin....

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[jay_camaro1]

what about this: COMPACtenna V.U.7/800 Antenna

 

[cmdrwill]

what about this: COMPACtenna V.U.7/800 Antenna

Smoke and Mirrors.........

 

[Inglewood]

..... well smoke anyway as it doesn't cover 2m.

 

[Project25_MASTR]

..... well smoke anyway as it doesn't cover 2m.

Yes it does…the compact version doesn't. The regular version does. Though the commercial manufacturers have gotten pretty good at matching multiple quarter waves on a single whip (max band width). The tri-band option for my Sharkee is broad banded enough to cover 2/VHF-Hi, upper portion of 70 cm to T-band, and then 780-894…


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[prcguy]

Its rated down to 144MHz, what's not 2m about that?
prcguy

..... well smoke anyway as it doesn't cover 2m.

 

[Starion1]

From personal experience I've used the Diamond Antenna X50C2 and have had good results.

~ X50A Dualband Base/Repeater Antenna Diamond® Antenna

According to the specifications, they claim a 4.5db gain on UHF and 7.2 gain on VHF. Although the band spread is shifted to the upper side of UHF/VHF, you should get adequate performance on both 2m and 70cm amateur bands while optimizing performance operating in the GMRS band. Best bang for the $$$.

 

[blastco2]

From personal experience I've used the Diamond Antenna X50C2 and have had good results.

~ X50A Dualband Base/Repeater Antenna Diamond® Antenna

According to the specifications, they claim a 4.5db gain on UHF and 7.2 gain on VHF. Although the band spread is shifted to the upper side of UHF/VHF, you should get adequate performance on both 2m and 70cm amateur bands while optimizing performance operating in the GMRS band. Best bang for the $$$.

Thank you! That is just about right for where and what I'm up to may have to order one and see how it works.