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Author Topic: 6m horizontal vs. vertical polarization  (Read 7202 times)

Posts: 539


« on: September 02, 2010, 10:55:22 AM »

I have a loop antenna for 6m, but it's not currently up.

I'm thinking of replacing this loop antenna with a ground plane antenna.  The problem with the loop antenna is that it's heavy and tricky to mount up high.  In fact, I once had the antenna fall down and break, and I had to order a replacement rod.

On the other hand, a ground plane antenna would be lighter, and the mount wouldn't require as much reinforcement.  One possibility is to solder thick solid wires to an SO-239.  Another possibility is to use a 6m Hamstick and add thick solder wires to the ground connection for the radials.

I know that the ground plane antenna is just as efficient and omnidirectional as the loop antenna.  However, a ground plane antenna is vertically polarized while a horizontal loop antenna is horizontally polarized.

How preferable is it to be horizontally polarized rather than vertically polarized on 6m?  I know that when the band opens, the horizontal vs. vertical issue is moot because the ionosphere flips the polarization around anyway.  Is local 6m activity usually horizontally or vertically polarized?

Posts: 2476

« Reply #1 on: September 02, 2010, 11:21:34 AM »

Repeaters and simplex FM usually use vertically polarized antennas.  SSB and CW usually use horizontally polarized antennas.

As long as both ends of a local QSO use the same polarization, it really does not matter.

Theoretically there is around 30dB of signal loss (isolation) if one LOCAL station is using vertical polarization and the other LOCAL station is using horizontal polarization.  The atmosphere and ionosphere and etc tend to confuse issues on long haul contacts, so it really does not matter on DX, but tradition says horizontal polarization for DX.

Dick  AD4U

Posts: 5

« Reply #2 on: September 02, 2010, 12:10:56 PM »

In the 1960's, 50.4 was the AM hangout and Cushcraft Halo's and Cloverleafs were the rage for mobile.  They were horizontal polarization as were the 5 element yagi's used at 50.250 (AM) and 50.112 (USB).

For 6 meter FM, 52.525 etc., the polarization follows the recycled Twin-V's, Motrak, MICOR's, Twin Coffins, Master II's, Super Car Phones and Dumont's which typically arrived with used vertical whips.

Today, the 6 meter FM repeaters are largely tower mounted and are recycled commercial verticals, thus vertical polarization is common which also gives a circular coverage.

So my answer is: It depends. Do you want to go AM/SSB or FM?  E-skip or rag-chew?  With the exception of a big discone, most antennas don't have the bandwidth to do both ends of 6 without a tuner and most feed lines are lossy unless matched.

Mounting a beam for vertical polarization on a rotor is a real pain, unless you mount 2 beams side by side.  Also, IMHO, ground planes (excepting the DB201L) are cousins to lightning rods. . .

Jim wa9vez

Posts: 21760

« Reply #3 on: September 02, 2010, 04:00:17 PM »

For FM, vertical is the norm.

For SSB-CW, horizontal is.

Tropo scatter maintains polarization very well, so contacts within a few hundred miles need to be similarly polarized or they just won't happen.

It's true that ionospheric polarization makes the differentiation unimportant.

However, unless you only operate 6m when there's ionospheric propagation, which might be 2% of the time overall, for SSB work you'd want to be horizonally polarized.

I don't think a horizontal loop is difficult to install or keep up, at all.  I use one mobile at 75 mph on a 24" mast over the roof of my van and it holds up just fine.  For it not to would imply a very weak support/mounting system.
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