Impedance matching by adding/subtracting open wire transmission line
A simple antenna tuner made from switches. How to determine the “best” transmission line lengths for multi-band center fed wire dipoles.
by Cecil Moore, W5DXP
“The superformula is a generalization of the superellipse and was first proposed by Johan Gielis in 2003″
Some superformula samples
Transmitting FM, AM, SSB, SSTV and FSQ with a Raspberry-PI
By @F5OEOEvariste (article at: rtl-sdr.com)
Based on the first section from Steve Reich’s 1967 piece Piano Phase.
“Two pianists repeat the same twelve note sequence, but one gradually speeds up. Here, the musical patterns are visualized by drawing two lines, one following each pianist.”
A network of Internet connected CW skimmers that display detected signals in real time.
Send a CQ and immediately get a list of reverse beacon stations that heard your call, from around the world, with time and signal report data.
Logs are collected in a database that is accessible for research.