You're looking at the wrong parameters when changing the length of
parasitic elements -- the primary effect on directivity and gain. Yes,
varying the length of the reflector changes the feedpoint Z, but it
mainly affects gain and directivity. Resonance and feedpoint Z should
be adjusted by varying the length of the driven element and the matching
section.
The YW program, included on the CDROM that comes with the ARRL Antenna
Book, is quite useful in studying the effects of element length, element
diameter, and element spacing on gain, pattern, feedpoint impedance, and
the bandwidth of both the match and the pattern.
73, Jim K9YC
On 10/29/2017 11:05 PM, Matt wrote:
Increasing the reflector width while keeping the driver constant will shift
frequency response down.
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|