I have been looking for an antenna that covers OIRT band since fantastic tropospheric ducting from Russia in 2012. I already have two huge masts with Körner 19.3 and 2x K6STI 9-el, so this time I was looking for something smaller, with boom length up to 4 meters. There are many projects for 70 MHz, but mostly narrow-band for the ham-radio usage. Besides the 65-74 MHz band I also intended to cover lower frequencies starting from 60MHz, especially for STLs via Sporadic-E, so I have decided to scale the 9-el K6STI wideband yagi.

OIRT 9-el

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Brian Beezley, K6STI has designed a very interesting 100″ 9-element yagi for the 88-108MHz FM band with a horizontal folded dipole and 3 reflectors. His antenna optimizer managed to achieve F/R up to 30dB and 7-8dBd gain over entire bandwidth. Currently, a shortened version of this antenna is known as Körner 9.2.

2x9el-small

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