I have been looking for an antenna that covers OIRT band since the tropospheric ducting propagation 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 60 MHz, 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 designed a 9-element Yagi for the 88-108 MHz VHF-FM band with a horizontal folded dipole and three reflectors. His antenna optimizer managed to achieve 7-8 dBd gain and F/R up to 30dB over entire bandwidth. The distance between first and last element is 100″ or 254 cm. I built two of them in 2013 for receiving vertically polarized signals.

2x9el-small

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