NEC-LIST: CFA modeling results comparison

Jack,
 
Thanks again for your 29 June reply, where I noticed that you use the
EZNEC/4D program, which I wanted to buy, but I got stuck with the
NEC-WIN Pro program, which is similar to the EZNEC.
 
Your modeling results where more precise than mine, because you used a
more precise grid-wire configuration. Also, you added the capacitive
top load.
 
I tried to compare your modeling results of June 9, 24 and 29, and I
found differences in the cylinder and disc impedances, and also gain.
Obviously, these differences are resulting from different phase shifts
at the cylinder and disc.
 
It is interesting to note, that the gain of the cylinder alone, with
-8.4 dBi ( 24 June ) is almost equal to your ( 9 June ) result, with
-8.3 dBi, where you feed both, the cylinder and the disc !
 
In my case, I did not get any gain, when feeding the cylinder with -45
deg, and the disc with + 45 deg , just reversed of your result.
 
I still believe, that a short antenna, like the CFA must have a low
radiation resistance, and therefore low efficiency, even if the gain
is not too low ! But again, your test results will show, who is right
!
 
I reread the " Conventional Explanation for 'Crossed Field Antenna',
in ELECTRONICS LETTERS, 13th Feb. 1992, by M.S.Smith. This paper makes
a lot of sense to me, and before I see actual test results of the CFA,
I still doubt all the great claims.
 
I intend to model a capacitive-loaded monopole, 10 meters high, with
eight 14 meters cross rods, just to check what gain and impedances I
will get. The CFA with top load is already approximately eight meters
high !
 
Max
Received on Tue Jul 06 1999 - 20:28:14 EDT