Tests on a 3 GHz ground plane Yagi

Classical dimensioning of a ground plane Yagi antenna for 3 GHz leads to a gain which is 2-3 dB less than predicted, but this can be overcome to some extent by additional directors. The impedance matching strongly depends on the size of the reflector, which should be by a factor of 1.2 longer than given by classical theory. The shape and size of the ground plane itself can be varied considerably with little or no effect on either the radiation pattern or the impedance characteristics but, on the other hand, inaccurate mutual positioning of the individual elements has a drastic influence. Material conductivity is not of prime concern     

High rate data link front end design and performance during AlphaMagnetic Spectrometer Space Shuttle flight, May 1998

In June 1998, Metsahovi Radio Observatory participated in a 10-day shuttle mission, STS-91, ground support activity by receiving, archiving, and making available, the so-called High Rate Data (HRD) from Alpha Magnetic Spectrometer (AMS). The goal of this particle physics experiment project was to detect antimatter in space. Some aspects of the HRD link performance are discussed