Principles of operation for dual band vertical antenna (2m/70cm)
 

Hi

Am I correct that in a dual band mobile antenna for 2M/70 cm - the lower
portion of the antenna is cut for 70 CM and the entire antenna including the
coiled portion is used for two meters? Does all or a portion of the coil
add to the length for either frequency?

Thanks for your help.

Ed AD5JV

Principles of operation for dual band vertical antenna (2m/70cm)
 

Ed Laughery wrote:
Am I correct that in a dual band mobile antenna for 2M/70 cm - the lower
portion of the antenna is cut for 70 CM and the entire antenna including the
coiled portion is used for two meters? Does all or a portion of the coil
add to the length for either frequency?

For mine, the coil acts as a loading coil on 2m and a phasing coil on 70cm.
--
73, Cecil http://www.qsl.net/w5dxp

Principles of operation for dual band vertical antenna (2m/70cm)
 

There are several types, so you need to give a better description of the one
you refer to.
The "Hershey kiss" one I have looks like a 2M 1/4 wave, but with a small,
3-4 turn coil at the base. It appears to be "5/8" on 440 and "1/4" wave
on 2. However, on 440 the 5/8 needs some series inductance to tune out the
capacitance of the 5/8. With this inductance in there, the 2M 1/4 wave has
un needed loading, so it has to be shortened for a better match. It all
fits. The frequency ratio is ~~ 3:4 and 5/8 is less that 3/4, so it is
shorter than both 1/4 and 3/4... Better get out the yard stick again and
verify my recollection...

73, Steve, K,9.D;C'I


"Ed Laughery" wrote in message
. ..
Hi

Am I correct that in a dual band mobile antenna for 2M/70 cm - the lower
portion of the antenna is cut for 70 CM and the entire antenna including
the
coiled portion is used for two meters? Does all or a portion of the coil
add to the length for either frequency?

Thanks for your help.

Ed AD5JV

Principles of operation for dual band vertical antenna (2m/70cm)
 

I think the Larsen operates as a loaded 2 meter, 1/2 wavelength
equivalent, and as a 2 elrment collinear on 440.

Ed Laughery wrote:
Hi

Am I correct that in a dual band mobile antenna for 2M/70 cm - the lower
portion of the antenna is cut for 70 CM and the entire antenna including the
coiled portion is used for two meters? Does all or a portion of the coil
add to the length for either frequency?

Thanks for your help.

Ed AD5JV