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[TowerTalk] Antenna measurements

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Subject: [TowerTalk] Antenna measurements
From: (
Date: Sat, 19 Jun 1999 12:32:04 EDT
Coils and traps enclosed in metal tubes are not neccessarily lossy to excess. 
Two examples of similar construction come to mind: !> Helical Resonators can 
acheive unloaded Q's of 3000 or more. These are copper coils inside a small 
cylindrical or square (usually copper but aluminum is also used) enclosure. 
Typical designs we usually see are for 144 and 432Mhz and are quite small in 
size. When you scale the design to h.f. you end up with dimensions that are 
strikingly similar to beam antenna traps. 2> power amplifiers used at h.f., 
v.h.f. and u.h.f. typically have a plate nductor mounted inside a metal 
enclosure with fairly close spacing. These circuits have high circulating 
currents and low losses on most bands.

73 de k5gw

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