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In the coming decades there is going to be a significant increase in the number of spacecrafts, orbiters, landers and rovers that will be launched into deep space on various exploration missions. The ground segment supporting such missions primarily consists of a high gain parabolic reflector antenna, which are legacy systems and represents a single point of failure. Moreover, with the return of humans to moon and the establishment of the lunar gateway, there will be significant increase in data and command traffic between ground control and space segment. Additionally with the entry of commercial parties, there will be a large number of constellations of satellites launched into low earth orbit (LEO), geostationary earth orbit (GEO) and Low lunar orbit (LLO). All of these will place significant stress on existing communications architecture. This paper examines the use of new and emerging technologies to develop innovative planar array tiles for active electronically scanned array (AESA) based deep space communications architecture that is highly modular, scalable and enabling multibeam operations across multiple spacecrafts in space.

This paper presents for the first-time a physics-based non-linear large signal model for Ka-band GaN power amplifier design using the new industry standard ASM-HEMT compact model. A novel methodology combining the effectiveness and accuracy of modeling the intrinsic device region with ASM-HEMT, and distributed effects at Ka-band with electromagnetic (EM) simulations is developed. The intrinsic semiconductor region for each finger of the GaN HEMT device is modeled with ASM-HEMT, and in a multi-finger device, the single finger model is coupled with EM simulations capturing distributed effects accurately. The developed non-linear model shows excellent accuracy with measured non-linear data for a commercial GaN-HEMT device, and with measurements performed on a Ka-band MMIC power amplifier.

The temperature response of field-effect transistors (FETs) to instantaneous power dissipation has been shown to be significant at high frequencies, even though the self-heating process has a very slow time constant. This affects intermodulation at high frequencies. A major difficulty in characterizing the self-heating process in microwave FETs is to differentiate between the self-heating and charge-trapping rates. An iso-trapping measurement technique is proposed by which it becomes possible to characterize the self-heating process in an FET in isolation from the effect of the charge-trapping process in the FET. The results of iso-trapping measurements performed on a GaN high-electron-mobility transistor are presented, and used to successfully characterize the self-heating process.