Microwave Intermediate Frequency (IF) Subsystem for Potential Nanosatellite and Space Wireless Communications

In wireless microwave communications schemes, heterodyne subsystems are normally used, taking advantage of the improved performance when compared to more basic direct detection and demodulation schemes. Heterodyne microwave communication schemes are based on two complementary subsystems: Intermediate frequency (IF) and high-frequency up/down conversion. In terrestrial, satellite and space communications, heterodyne schemes are preferentially used. In such a perspective, in this work, de design, realization and characterization of an IF subsystem for wireless communications, in particular focused to nanosatellites (CubeSats of 3 to 6 units) operating in the near-earth telecommunications X-band (7190–7235 GHz), is reported. The developed IF subsystem operates at a center frequency of 1.1 GHz, covering a band of at least 300 MHz. The IF subsystem feeds a modulated subcarrier to the up-conversion subsystem for generating a 7.2 GHz up-link microwave carrier The proposed IF subsystem includes the design of an IF PLL-based oscillator at 1.1 GHz and a quadrature modulator as a starting configuration for analog and digital communications capabilities.