Large‐scale ionospheric structures associated with mid‐latitude spread F

This paper contains a brief survey of some of the papers, dating back to the 1950s, which support the concept of large‐scale structures being associated with the phenomenon of ionospheric spread F. Then, three different recording techniques, which are effective in revealing evidence of large‐scale structures at times of spread F, are illustrated and discussed. These techniques involve (1) sweeping the gain of the receiver, (2) imposing phase fringes on ionogram traces, and (3) identifying interference minima resulting from overlapping traces.