MIMO channel measurements on a ionospheric HF (3–30 MHz) radio link

MIMO architectures are generally based on antenna arrays with spatial diversity. An implementation in the particular context of trans horizon transmission through the ionospheric channel copes with the problem of prohibitive array aperture, the wavelength being decametric in the corresponding HF frequency band (3-30 MHz). Therefore, we proposed an alternative, based on the diversity in transmitted polarizations and set up in an original 2×2 MIMO system involving compact antenna arrays. Experimentations, carried out on a 280km long transmission, are presented. They provide a MIMO channel state information which underlines a low inter correlation for the 4 possible propagation paths. Additionally, the stationarity duration of the ionosphere is estimated for the radio link under test.