Friday, January 7, 2011

4m & 6m Trapped Dipole

The VRC8000 covers both, the 6m and 4m bands. It would therefore be desirable to use one aerial only for the rig. Quick and dirty idea, a trapped dipole.

Assuming a trap frequency of 70.2MHz, the calculated values would be L=0.5┬ÁH and C=10.3pF.
Playing with MMANA, I found a span for the 4m dipole of 205cm. The additional radiator wires for 6m would amount to 26.8cm each. In the 6m band, 51.0MHz was taken as design frequency, due to the FM-nature of rig mentioned above.

The design has not been put to reality yet. However, if one wants to play with a simulation, here is the mmana-file:

4m / 6m trapped dipole
*
50.5
***Wires***
3
1.041e-17,    -1.025,    1.041e-17,    1.360e-16,    1.025,    1.360e-16,    8.000e-04,    -1
0.0,    -1.025,    0.0,    1.642e-17,    -1.293,    1.642e-17,    8.000e-04,    -1
0.0,    1.025,    0.0,    1.642e-17,    1.293,    1.642e-17,    8.000e-04,    -1
***Source***
1,    1
w1c,    0.0,    1.0
***Load***
2,    1
w1b,    0,    0.5,    10.280069,    0.0
w1e,    0,    0.5,    10.280069,    0.0
***Segmentation***
800,    80,    2.0,    1
***G/H/M/R/AzEl/X***
2,    7.0,    1,    50.0,    120,    60,    0.0
###Comment###
Mod by Joachim, PA1GSJ 07/01/2011 20:33:45
Created by Joachim, PA1GSJ 07/01/2011 20:21:12
 

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