[OZAPRS] Scaling APRS antenna

[Andrew Rich]

410 to 438 is a 6.4 % decrease in size

410 is 93.6 % of 438

Reflector is 36 cms long

therefor 6.4 % of 36cm = 2.3 cm

therefor the length of a reflecter should be 36cm - 2.3cm = 33.7cm

therefore 36cm - 33.7cm = 2.3cm / 2 = take off 1.1 cm from reflector tips.

Driven i will look at it is 70cms loop which comes out to 428 MHz.


-----Original Message-----
From: Andrew Rich [mailto:vk4tec at tech-software.net]
Sent: Saturday, 18 September 2004 12:18 PM
To: G T & C A Beagley; ozaprs at marconi.ics.mq.edu.au
Subject: RE: [OZAPRS] Scaling APRS antenna


410 to 438 is a 6.4 % decrease in size

410 is 93.6 % of 438

directors are 28.5 long at 410 MHz

therefor 6.4 % of 28.5cm= 1.824cm

therefor the length of a drirector should be 28.5 - 1.824 = 26.676

therefore 28.5 - 26.676 = 1.824 / 2 = take off .912cm each director tip.

sound right ?
 
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