Analysis and design of a point-to-point radio-link at W band for future satellite telecommunication experiments

In the last years EHF (Extremely High Frequency / 30-300 GHz) band is acquiring more and more interest in different fields, such as telecommunications, radar applications and Earth observation, due to advantageous characteristics. Actually, the higher operating frequency with respect to traditional ranges (Ka and lower) allows the achievement of some advantages: no crowding in frequency and hence reduced interference, large bandwidth availability, reduced antenna and electronic components size, and more security in point-to-point links due to smaller beamwidth. Moreover, the increase of frequencies allows the realization of, with respect to lower bands, high resolution applications, as radar images and Earth Observation sensors. However, although W band is an attractive range, it is yet an experimental frontier since no telecommunication mission has been carried out and the technology development at this frequency is still poor, costly and relatively not ready. However, some specific applications, such as radar and radio-astronomy, and just for some frequencies (typically around 94-96 GHz), make an exception. Considering this context, a very significant and preliminary step to useful W band exploitation for terrestrial and satellite telecommunications is represented by the analysis and the validation of a terrestrial link operating at these frequencies with the capability of carrying out transmission/reception experiments. In this frame, the University of Rome, "Tor Vergata" in collaboration with the company Rheinmetall Italy is carrying out an experiment based on the establishment of a W band point-to-point terrestrial link over a distance of some kilometers between the University of Rome "Tor Vergata" (Rome) and Villa Mondragone (Frascati, near Rome). The work aims at showing an overview of the preliminary design of the experimental W band terrestrial air link. It will be very useful mainly for two reasons: firstly, in order to provide a test-bed for evaluating atmospheric effects (fading and scintillation, along with amplitude, phase, and polarization distortion) that could compromise the performance of satellite-to-ground communications systems operating at these frequencies; and secondly to verify performance of W band critical technology. The last part of the work investigates the possibility of using, in addition to the traditional approach, Impulse Radio Ultra Wide-Band (IR-UWB) technology for realizing very high bit-rate point-to-point Line Of Sight (LOS) last mile links beyond 60 GHz. This paper will firstly provide a preliminary orographic and propagation analysis of the terrestrial link. Then, a detailed insight into link architecture and transmitter/receiver schemes will be reported taking into account constraints related to the characteristic of the available HardWare (H/W) in Rheinmetall Italy. Finally, an accurate link budget for dimensioning the system in terms of maximum link capability will be reported.