Efficiency and gain of Small Transmitting Loops (STL)

Small Transmitting Loops (STL) are loops of less than about 0.1λ in diameter or about 0.3λ in circumference. Below these limits, the current around the loop is almost uniform and this permits a simplified analysis.

STL are commonly known by Hams as “magnetic loops”, but that term is rarely used in recognised antenna text books.

The efficiency and free space gain of a circular STL can be easily estimated by calculation from simple measurements. Continue reading Efficiency and gain of Small Transmitting Loops (STL)

Galvanised steel wire OCF dipole

I was chatting on the weekend with a new ham who was inspired by an article in Amateur Radio to build an OCF dipole using galvanised fence wire.

I have not seen the article, but he recalled that it recommended single core 1.25mm galvanised wire as quite suited to the task of an 80m OCF dipole. The wire consists of a mild steel core with a thin layer of zinc. Continue reading Galvanised steel wire OCF dipole