In article et,
"Doug" wrote:

"Jon Gauthier" wrote in message
...
I haven't fired up EZNEC yet, but I was wondering how a standard 3dBi
marine whip would perform on the 2m ham bands. Since the marine
frequencies are 156.050-157.425 MHz, what could I expect at 144-148 MHz?

If it won't cut it, then does anyone have any recommendations for a
dual-band antenna (commercial or home-built)?

Jon

You could expect 3:1 or worse SWR unless you found a "dip" at certain
frequencies in the 2 meter ham band. I believe Morad makes a 2 meter version
of one of their marine antennas, however, their web site says "under
construction" when I checked it today. I usually use a Larsen (Radiall)
antenna on a boat for 2 meter ham band or VHF high band public safety
frequencies.
Do not try using a ham rig and a marine VHF radio on the same antenna, as
sooner or later you will accidentally end up transmitting into the other
radios receiver. Modified ham rigs on the marine band are illegal.
73
Doug K7ABX




Actually Morad has both a 146HD and a 146HD10db in their designs,
as I have one of each, of the original prototypes, that Eddie Zanbergen
gave me years ago. The 146HD is up on the roof of the cabin and the
146HD10db is in a tube out back waiting for the new "Retirement House"
to be constructed. All the designs for Morad antennas were first
tested in the associated Ham Bands next to the Maritime Mobile Bands.

Most any VHF Antenna will work just fine on both 146 and 156, if
one is just trying to communicate, as SWR isn't really all that important
at frequencies that are horizon limited, and have Sufficent Power
(25 watts) to reach the Radio Horizon. A leaky dummy Load can
communicate a couple of miles at this frequency. Efficent coupling
into the ether at VHF Frequencies is relatively simple, when compared to
the MF and HF counterparts. The higher frequency, the less finiky, and
wider bandwidth, an antenna will operate over, for just communicating.
At the 25 Watt output power level, just about anything including a "Wet
Noodle" will communicate to the Radio Horizon at VHF Frequencies.
Ever wonder why you don't see a whole pile of "Antenna tuners" for VHF
Frequencies? It is because what little you would gain, by any tuning,
wouldn't show up by increasing the Radio Horizon in any meaninful way.

This isn't like your trying to do Moonbounce, or anything. It is like
going for 25 to 30 miles over water and looking at a Path Loss in the
high 80 or low 90 db's. Not a very difficult proposition in the radio
world.


Bruce in alaska
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