External ferrite aerial units for short. medium and long-wave radios

Over the years, the writer has often needed handy, external aerials for short, medium and long wave radio receivers, such as communication, vintage and modern domestic models. This involves a wide variety of aerial input impedances with, perhaps, coaxial, twin-feed or simple end-red aerial earth sockets. Furtherrnore, these aerial units should be capable of being taken to the Iocation of the radio, rather than the more usual method of taking the radio to the aerial. The immediate target was a frequency range of 150 kHz (2000 m) up to, and including, the 15.10-15.45 MHz (19 m) band.