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#1
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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 |
#2
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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 |
#3
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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 |
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