Log Periodic yagi?
 

I came across plans for a Yagi with a few LPDA elements. What are the
advantages of an antenna like this. I figure you are trading gain for
bandwidth and there are easier ways to do it than LDPA

Jimmie wrote:
I came across plans for a Yagi with a few LPDA elements. What are the
advantages of an antenna like this. I figure you are trading gain for
bandwidth and there are easier ways to do it than LDPA


Sounds like you have found the plans for Oliver Swan's (original Patentee)
antenna. these were mostly made for six meters. K.L.M. , if I remember ,
aquired the patent, then proceeded to produce antennas for vhf, useing
this design. The original reason that he made these for six meters (Swan),
was 2 fold-- one, to improve the bandwidth of the antennas, and two, (remember
this was before cable tv was widely used) to limit TVI( an antenna with a built
in TVI filter !. A consideration for KLM useing this design was additional
bandwidth, consistant foo max gain (high gain antennas are pretty touchy about
gain over bandwidth). Hope this info helps, Jim NN7K

NN7Kex(NOSPAM)k7zfg wrote:

The original reason that he made these for six meters (Swan),
was 2 fold-- one, to improve the bandwidth of the antennas, and two,
(remember
this was before cable tv was widely used) to limit TVI( an antenna with
a built in TVI filter !. A consideration for KLM useing this design was
additional bandwidth, consistant foo max gain (high gain antennas are
pretty touchy about
gain over bandwidth). Hope this info helps, Jim NN7K

Oh, forgot to explain just HOW the Swan antenna limited TVI !
reason was that the antenna was relatively flat in gain, over 1-2
MHz of six meters. Above around 53 MHz, or below 49MHz, theoretically,
the antenna pattern collapsed, and the swr rose dramatically.
This was what was claimed, If remember the spin from those times! Jim