[VHFcontesting] Antenna choices for new rovers in VHF

[Marshall Williams]

Hello to the group....I think that I recall an antenna with 6(or so) 432 
elements in front of 3 el of 2M.  I think that it was a Kent, WA5VJB, 
design.  The 432 elements in the front were essentially unaffected by 
the 2M elements in the read and would only add about 3 ft to the antenna 
length. 

With a design like that, the only problem would be trying to figure out 
how to have a single feedline.  As noted, the ICOM 706 type radios all 
have two coax connectors on the output....HF/6M and 2M+432.  This means 
that the 6M antenna can and should be completely independent of the 
2M+432 antenna.

We have several rovers that have the KU4AB "dual loop" antenna for 2M + 
432.  It has a single feedline and so it is very simple.  Of course, the 
minus is that it is only a loop, not a beam.  However, we work these 
antennas out to over 100 miles in every contest.  That is enough for 10 
grids, which is all you can expect from new rovers.  The original 
designer of that antenna is David, WT4E, who also sells his version.  
Slap one of these on a tri-mag mount and you are good to go.

For 6M, we often use a simple mag mount vertical.  We use the 5/8th wave 
2M vertical, which just happens to be a 1/4 wave on 6M and works 
fine--especially for contacts of 100 miles or less.  We have a 3el 
vertically mounted yagi at 110ft just for working rovers with the mag 
mount vertical on 6M.  Works great. 

The simpler the better for new, just starting out rovers. 

73 Marshall K5QE

Tom Carney wrote:
> Interesting discussion.  I am primarily a rover and face somewhat a 
> similar requirement to simplify the antenna situation.  For me, it's 
> more the desire to minimize the time to put up and take down the 
> antennas than the cost.
>
> First comment, since the 706 (and FT-100) have two antenna connectors, 
> I'm not convinced it worth the trouble to go for a single feedline.  If 
> you do, you end up with some form of duplexer at the radio end of the 
> coax.  Or at the least, a coax switch.  I have a similar problem in 
> feeding a 2M and 432M antenna from the single antenna connector of the 
> radio and tried a switch at first but would frequently forget to switch 
> the antenna.  A duplexer is similar in cost to the extra feedline up to 
> 50/60 feet.  More if you use RX-8X for 6M.
>
> I've tried modeling several different antennas just to get 2M and 432 on 
> a single boom without much success.  The presence of the 2M elements 
> seems to distort the 432 pattern.  At least that what EZ-NEC predicts. 
> For example, I recently modeled a dual band yagi that appears to be a 
> Cushcraft A270-10S.  This antenna has five elements on each band.  The 
> elements for one band are mounted above the boom, the other band below. 
>   Cushcraft quotes 10bdi gain for each band, but EZ-NEC predicted only 
> about 8 dbi on 432.  Remove the 2M elements from the model and the gain 
> jumps over 2db.
>
> Perhaps some form of quad might be a solution, haven't tried that.  The 
> N6NB pack uses a three element multiband quad for 2, 222, and 432 and 
> Wayne quotes a gain of 7-8 DB over a dipole.
>
> 73,
>
> Tom K6EU
>
>