Is there some magic to a dual band antenna? I have a Yeasu FT2980 2M radio and when I bought it I got an antenna I cut to length for the frequency I use and an NMO base, I picked the middle of the 2m band, like 146MHz if I remember what I did. Now I'm looking at dual band radios (Icom 2730A) which will transmit on both 2M and 70cm. I'm looking at dual band antennas and I have not done the math regarding their length. But what frequency are they resonant to? Or is it a factor, clearly a piece of wire 3' long will be a fraction of a waive for several frequencies, but I just don't know enough about this stuff to understand how a dual band antenna works. Is there some magic happening in the base I don't know about? I've been looking around on the interenet but I can't seem to find an explanation. They all seem to be pretty short so I'm thinking I'm comprimising my 2M performance. Still researching but I thought I'd ask you guys. What if I just use my 2M antenna, will it just be crap for 70cm? Guess I need an SWR meter.
A full waive at 440MHz is (2ft. 1 - 17/32in. or 0.648 M)
3/8 wave at 146MHz is (2ft. 4 - 7/8in. or 0.733 M)
courtesy Amateur Vertical Antenna Calculator - http://www.csgnetwork.com/antennaevcalc.html
So it is just a comprimise that works everywhere but not well, or again, am I missing something?
Thanks
Rob
KJ7JDB
A full waive at 440MHz is (2ft. 1 - 17/32in. or 0.648 M)
3/8 wave at 146MHz is (2ft. 4 - 7/8in. or 0.733 M)
courtesy Amateur Vertical Antenna Calculator - http://www.csgnetwork.com/antennaevcalc.html
So it is just a comprimise that works everywhere but not well, or again, am I missing something?
Thanks
Rob
KJ7JDB