>Jack:
>
>Have you modeled fan dipoles to see if it is better to have the
>low-frequency elements on the top or on the bottom?
>
>George
Sorry, I have confused the issue. I was modelling fan monopoles. A
fan of wires apex down fed by a single wire against a GP.
The purpose of my study was to determine the resonant frequency of the
antenna system used by Marconi for his December 1901 transatlantic
experiment. But then I got interested in fans because of the
interesting effects I was observing, which I have spoken about.
I did numerically model an HF fan monopole for a broadband receive
application, but that was quite a while ago [2]. I did not carry out
a detailed study and had no measurements to support my numerical
modelling, but I was on the right track. I found that if you wish to
get rid of the transmission line type resonances run a jumper wire (or
wires) across the fan, joining them at midpoint as well as the ends
(or 2 jumper wires besides the wire joining the ends). We then begin
to simulate a solid triangle, and so the currents start to concentrate
on the edges of the "fan".
Lots of fun.
Jack
2) Belrose, J.S., "Modeling HF Antennas with MININEC -- Guidelines and
Tips from a Code User's Notebook", ARRL Antenna Compendium Volume 3,
1992, pp. 156-164.
_____________________________________________
John S. (Jack) Belrose, PhD Cantab, VE2CV
Senior Radioscientist
Radio Sciences Branch
Communications Research Centre
PO Box 11490 Stn. H
OTTAWA ON K2H 8S2
CANADA
TEL 613-998-2779
FAX 613-998-4077
e-mail <john.belrose_at_crc.ca>
_____________________________________________
Received on Fri Mar 03 2000 - 04:14:18 EST
This archive was generated by hypermail 2.2.0 : Sat Oct 02 2010 - 00:10:40 EDT