A full wave antenna for 150Mhz (disregarding end effects) is 2 meters.
It's for something much lower frequency than that. For full wave
antenna length in meters divide 300 by frequency in Mhz.
Conversely, to discover design frequency in Mhz of a full wave antenna
divide 300 by antenna length in meters. Since that antenna appears to
be about 6 meters long the (full wave if it's that) frequency would be
about 50 MHz. What's at 50 Mhz? I dunno anymore.
Chuck Norcutt
(who once studied antenna theory in the USAF some 50+ years ago)
On 12/17/2012 5:54 PM, Jim Nichols wrote:
> It seems they use a lot of frequencies in the 148 to 150 Mhz range. Could
> this be a full wave antenna for those frequencies?
>
> Jim Nichols
> Tullahoma, TN USA
> ----- Original Message -----
> From: "Moose" <olymoose@xxxxxxxxx>
> To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
> Sent: Monday, December 17, 2012 4:17 PM
> Subject: Re: [OM] IMG: Airport Observations
>
>
>> On 12/17/2012 1:04 PM, Jim Nichols wrote:
>>> ...
>>> I stopped to take a look at the new Civil Air Patrol Mobile Unit, used
>>> for searches for downed aircraft. I was impressed by the communications
>>> antennae:
>>> http://gallery.leica-users.org/v/OldNick/59+edit.jpg.html
>>
>> Unless fundamental principles have changed, that antenna looks like a poor
>> design.
>>
>> Antennas needs a ground plane for maximum efficiency. In this case, the
>> ground plane is the vehicle. By placing the
>> antenna off one corner, you get a highly asymmetric sensitivity pattern,
>> high to the right front and low to the left rear.
>>
>> OTOH, hiding about a third of the length behind the van for about a third
>> of directions should negatively affect
>> sensitivity.
>>
>> I wonder what frequency it is for. If the whole thing is antenna, it's
>> quite long wave. If not, and the small things
>> along its length are tuning coils, rather than connectors for sections,
>> roof antenna(s), perhaps hinged, should be more
>> electronically effective.
>>
>> Antennae Head Moose
>>
>> --
>> What if the Hokey Pokey *IS* what it's all about?
>> --
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>>
>
>
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