[Antennas] Elementary Antenna Question

Fri Oct 2 08:55:41 EDT 2009

>>Basically why does the antenna resistance(50 ohms) does not correspond 
>>with
the SWR dip?
Are you referring to "50 ohms" reading on the analog meter on the 259? If 
so, that's the "Z" the meter is reading and the 259 is calibrated for 50 ohm 
input. When the instrument sees 50 ohms Z, it reads 1:1 SWR. The proper 
way to adjust this thing is to set the MFJ to the desired freq of use and 
tune the quad elements for a reading of 0 "R" on the digital meter while 
temporarily ignoring the "Z". When R=0, the antenna is at resonance. The 
"Z" should read somewhere in that 30 something ohm region (whatever the 
characteristic Z of your type antenna) and the SWR something greater than 
1:1. At 0 "R" is where you adjust the matching device (tuning stub in your 
case) so the line sees a 50 ohm load. Now you are tuned (resonant) AND 
matched.
If you really want the best explanation, go to W8JI.com and read more 
accurate details from the guy who came up the 259.
73,
Tom - AA1NZ