Attach directly to radio?

Started by KC3AOL, August 24, 2013, 07:53:41 AM

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Lamewolf

Quote from: KC3AOL on August 24, 2013, 07:53:41 AM
Being a new ham, I don't have a lot of experience and I was wondering if attaching an antenna directly to a mobile radio (no coax) would work or is the coax needed to get a good SWR? For example, take a Kenwood TM-V71A and attach a Comet CA-2X4SR. I was just thinking a setup like that might be good as a backpack rig or a good portable system.

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The feedline is not what resonates the antenna but the outside of the coax shield can act as a counterpoise if there is a lack of a proper ground system.  What resonates the antenna is actually adjusting the length of the antenna to bring the swr into a useable range, therefore you can get by without coax if you supply a proper ground system.  The ground system is half of the antenna and is required for the antenna to radiate properly.  But, endfed half wave antennas can be operated without a ground systme since they are voltage fed, not current fed,  So there is no real reason to use a counterpoise on it, but it is smart to supply a good safety ground at least.