On 4 May 2007 16:17:09 -0700, Telstar Electronics
wrote:
+++On May 4, 5:44 pm, Frank Gilliland wrote:
+++ Not really. Insertion loss of a [ferrite] balun could negate any gain
+++ you may get by impedance matching. It is also fixed, while a coax stub
+++ can be easily 'retuned' by simply pinning the coax. Not only that,
+++ since the antenna is (hopefully) way up in the air, the coax used for
+++ matching is either incorporated in the line or hung from the side,
+++ making any worries about extra coax "kicking around" a non-issue. You
+++ should be more worried about where you're going to put that nine
+++ square feet of ground plane.
+++
+++Pure rubbish... a balun would have perhaps 0.1dB insertion loss. The
+++antenna gain is perhaps twenty times that!
+++www.telstar-electronics.com
+++
*************
Baluns and RF transformers can be loss. Many factors come into effect.
These include wire guage, operating frequency, power levels, load and
source vriations and core material. Also not to forget connetor
losses.
A well designed Balun or RF transformer will comparable low loss
performance of a coaxial matching section. There are some benefits for
RF transformers and baluns in that they are considerably more
broadbanded. Over narrow bandwidths the coaxial matching section can
be more tolerable to impedance variation from both the load and the
source.
james