In 1991 we played around (OK3YEC and OK3CAV) with the very famous HB9CV antenna and wanted to convert it to 4 elements. We spent a lot of time on the measurements, and that's why we won't let the article, which was published in the 1991 Holick anthology, fall into oblivion.
Our variant of the antenna was measured by the well-known antenna technician Jardo OK1ZN and he proposed a more suitable adaptation to it. We made the antenna from the then known 3-element components yagi antennas and used in RK OM3KXM.
According to our experiment, they made this antenna at 7 MHz and are using it successfully in RK to this day OM7M. PDF article HB9CV you can download .: HERE :.
Jano OM3UU ex OK3YEC and Jaro OM1II ex OK3CAV