ETS-II Experiments Part V: Effect of Ionosphere

Propagation characteristics of gigahertz and very high frequency waves through the mid-latitude ionosphere have been studied applying the coherent beacon signals of 1.7, 11.5, and 34.5 GHz and the 136-MHz telemetry signal, which are emitted from the geostationary Engineering Test Satellite Type II (ETS-II). Total electron content (TEC) was obtained by measuring the differential phase shift between 1.7 and 11.5 GHz waves and also by the Faraday rotation of the 136-MHz carrier, the former method being more sensitive than the latter one for detecting fluctuating TEC. During the observations, amplitude scintillations at 136 MHz and 1.7 GHz, usually accompanied with an irregular variation of TEC, were recorded frequently in the nighttime and sometimes in the daytime. Specially noted is the 11.5-GHz scintillations less than 0.8 dBp-p that were observed during the severe magnetic storm on February 15, 1978, simultaneously with 136-MHz and 1.7-GHz scintillations. This was the first observation showing that the disturbed ionosphere affects waves above 10 GHz. Presented first are the techniques for the ETS-II ionospheric wave propagation experiment, including a description of the coherent receiver system in the gigahertz frequency range at Kashima and a description of the 136-MHz Faraday rotation receiver at Kokubunji. The capabilities of the facilities for monitoring the mid-latitude ionosphere by giving some observational results are then presented.