How to build a UHF antenna... - Page 162 - AVS Forum
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Old 11-30-2014, 03:09 PM
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A Bowtie improves SWR Bandwidth compared to a Dipole....a VERY FAT Dipole is needed to even come CLOSE to what a Bowtie does.
The FATTER Bicone (aka "Caged Dipole") may improve SWR Bandwidth....it does NOT significantly improve Raw Gain.

Expanding the "Fatness" into another Dimension (X-Coordinate) only provides a SMALL improvement in Raw Gain and the already sufficient SWR provided by the Bowtie (esp. when used with a Reflector which further improves SWR)....and chews up a LOT more metal....increasing cost and wind resistance.

Which is why you'll very rarely come across them....except in "Calibrated" EMI/EMC Measurement Antennas. The fol. is fairly "typical", with a fairly narrow bandwidth range where SWR is acceptable:
http://schwarzbeck.de/Datenblatt/k9116.pdf
http://schwarzbeck.de/Datenblatt/s9116.pdf

When specifically designed to minimize SWR, they CAN provide a small improvement in performance....just don't expect much more Raw Gain than an equivalent FAT Dipole:
http://glendash.com/Dash_of_EMC/Mode...g_Antennas.htm

Last edited by holl_ands; 11-30-2014 at 04:47 PM.
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