Topband: Radiation Resistance

[Dave Cuthbert]

Robert, some questions:

Does the 55 ft vertical begin 10' above earth for a total radiator length
of 45 ft?
What frequency?
The 45 deg angle doesn't work with the length and radial end height.

At 1.83 MHz a 55' radiator/top wires with the base 10' above earth, and
eight 67' radials at 10 ft, the radiation resistance is 8.7 ohms. I
believe it should measure closer to 9 ohms than the 29.7 ohms you measure
(implying GND loss of 21 ohms). Are the radials decoupled from earth GND
with a high-Z feedline choke? I'm using EZNEC the NEC-2D engine.

For a 45' radiator/top wire with base 10' above earth and eight 67' radials
at 10' the radiation resistance is 5.3 ohms.

    73, Dave KH6AQ

On Sat, Mar 7, 2020 at 8:59 AM Chortek, Robert L. <
Robert.Chortek at berliner.com> wrote:

> Good Day!
>
> Does anyone know the radiation resistance of a 55 foot vertical #12 wire,
> top loaded with 2 41 foot #14 wires sloping at 45°, with their ends at 35
> feet?
>
> I’m curious about the efficiency. The fee point impedance is 29.7 ohms,
> and I’m using eight 1/8 wave elevated radios at 10 feet.
>
> Please and thank you!
>
> Bob
> Robert L. Chortek
> _________________
> Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
>