I was thinking most any dual band 2M/70CM ham antenna would work fine for me to operate on the GMRS and MURS bands but it is not really true. The antennas can not tune effeciently to those frequencies. I am finding if I want to operate mainly in those bands I need an antenna designed and tuned for them.
In trying to keep costs down I found a few to consider that seem to do the job.
This one I found on Ebay:
http://www.ebay.com/itm/Dual-Band-VHF-UHF-Base-Antenna-Ham-Commercial-MURS-GMRS-FRS-DBJ-1-/121467477149?
It might be other places but it appears to be a kit that requires some assembly and a piece of PVC pipe and the hardware to mount it. I can not find a company that sells it complete. It appears to be an individual making them and selling them on ebay.
Then there is the Slim Jim sold by Two Way Electronics which appears to be a very portable and affordable unit that can be portable, hung on the wall inside the home or used with a piece of PVC to to mount it on a mast outside or in the attic.
http://www.2wayelectronix.com/Dual-band-MURS-GMRS-Slim-Jim-Antenna-dualmurs.htm. Here is the owners web site with more info and ideas on how to mount and tune the antenna. http://www.n9tax.com/Slim%20Jim%20Info.html
The other options is a little more expensive but seems to be the better built and designed J-Pole Antenna meant to be mast mounted and seems to be indestructible and made by Arrow. http://www.arrowantennas.com and click on Open Stub J-Pole and the band you are looking for.
Another company makes a single band GMRS mast antenna. It is not dual band but seems well made and with plenty of gain made by DPD Products. http://www.dpdproductions.com/page_gmrs.html
So far these appear to be the best options I can commercially or to buy to operate efficiently on the GMSR and MURS radio bands. Of course there are tons of homebrew plans and options that can be made. You can made a simple 1/4 wave ground plane to your own J-Pole or Yagi or Loop antennas. Here are many plans here. No matter what you do, the best plan is to use an antenna that is designed to do the job you want it to do.
No matter what antenna you end up with, you will need a SWR meter to test it with. You can spend a lot of money on these for sure. About the least amount of money you can spend and still get one that works and works across the 2M and 70CM ham bands is the http://redmancb.com/custom-lighted-workman-104-swr-watt-power-test-meter-vhf-uhf-ham-radio-120-500-mhz-dual-band/. It is not perfect but seems to get you on paper and some idea of where you are.
73 and see you on the air.
Randy May Family in Hillsboro Oregon 