Topband: Topband loaded dipole

[DAVID CUTHBERT]

110' loaded dipole:

Here are NEC simulation results for a 110', 1.85 MHz dipole placed 50' above
'average' Sommerfield-Norton GND. The VSWR bandwidth is for the stated input
impedance. For example, the centered loaded case with a 1:4 balun, or a 90
deg section of 25 ohm line, or with a hairpin inductor.

The loading coils are assigned a Q of 300, which is attainable with close
wound #14 AWG THHN (house wire) on a 10 cm diameter PVC form.

center loading                   62 uH coils    63% efficiency     Rin = 12
ohms    3:1 VSWR bandwidth 14 kHz

coils 25% from feedpoint    77 uH coils    66% efficiency     Rin = 15
ohms    3:1 VSWR bandwidth 15 kHz

coils 50% from feedpoint  114 uH coils    66% efficiency     Rin = 20
ohms    3:1 VSWR bandwidth 14 kHz

coils 75% from feedpoint  220 uH coils    69% efficiency     Rin = 30
ohms    3:1 VSWR bandwidth 12 kHz


   Dave WX7G