ACMarine or Procom Denmark VHF Antenna

[Quickflash]

On my search for new antenna's, I have come across the Danish brands ACMarine and Procom. Does anybody have any experience with these brands ? Thanks

[Salty John]

I've heard of this company, they seem OK.

In your search for a vhf antenna be careful that you pick one that either doesn't need a ground plane (typically 1/2 wavelength antennas) or that you have an adequate ground plane, or you won't get the performance you are hoping for.

Those tall 5/8 wavelength antennas need a ground plane. Some manufacturers claim they have a ground plane 'included', whatever that means, whilst others warn you to provide a good ground plane.

On RIBs it can be difficult to provide a good ground plane, so be careful.

[Quickflash]

Thanks, John, but what does a "ground plane" mean ? In my case the antenna would be mounted on top of a T-Top. How would I know if I do or don't have adequate ground plane ?

[martini]

John will know much more about it than me but a ground plane is usually a copper wire or mesh panel laid in the bottom of the boat, often on long distance sail boats etc it's actually built into the hull during lay-up. It's purpose is something to do with creating an RF ground to the ocean, bit like a lightening conductor but for grounding radio signals.

Very rare to see a vhf antenna that needs a ground plane, it's usually seen on SSB antennas.

[Salty John]

As martini says. Sometimes the mass of metal items on the boat below the waterline bonded together by copper foil is enough, sometimes you have to add copper screen or an external grounding plate. Anyway, it's necessary for SSB radio and other HF transmissions but not usually on VHF except where, typically, 1/8 and 5/8 wavelength antennas are used.

A good groundplane is relatively easy to achieve on larger boats but I have no experience with such a problem on RIBs, hence my comment about looking for an antenna that doesn't need a groundplane.