The aim of this paper is to present a novel and compact transmit/receive module (TRM) for enhancing antenna performances to be employed in space applications. The key advancement is the use of a 3-D technology which, to the best of our knowledge, would be for the first time introduced in the space industry for hermetically packaging RF modules. The 3-D module development is based on the highly demanding specifications of space active electronically steerable antennas (AESAs); the TRM consists of two ``submodules'' electrically connected by an ad hoc interposer. The complete electrical design process, together with a comprehensive discussion on electromagnetic, mechanical, and thermal aspects, is presented, and the achieved module performances such as gain and return losses are detailed. Moreover, several manufactured samples are measured to validate the simulated design, and the excellent results in terms of gain, noise figure, and output power fulfilling the target specs are presented and discussed. The presented data, characterized by a limited variability among the 10 measured samples, make the proposed design and the manufacturing process a good candidate in terms of potential reliability for building the next generation of high-performance space AESA.

Earth observation from space radar is based on the active electronically steerable antenna (AESA) whose performances count on reliable and powerful transmit/receive modules (TRM). To this aim, as a follow-up of the successful demonstration of a low-footprint transmit/receive hybrid module concept based on 3-D packaging and interconnect technologies (3DTRM), the interest for carrying out additional development work took a further step aiming at achieving a three-fold module performance improvement as well as at consolidating the novel proposed 3-D technology for space applications. First, the possibility of performing an AESA highly accurate calibration was implemented by embedding a wide band, high directivity directional coupler in the module circuitry without any total module footprint increase. Second, the heat extraction capability of the metal-ceramic hermetic package was enhanced through a re-design of the monolithic microwave integrated circuit (MMIC)-to-sink interface. And finally, the gallium arsenide (GaAs) MMIC high power amplifier (HPA) of the first 3DTRM version was replaced by a gallium nitride (GaN) HPA MMIC, obtaining both a higher transmit output power at 5 dB of compressed gain and an improved power added efficiency (PAE) at module level.

The roadmaps of satellite-based synthetic aperture radar (SAR) systems show a trend that requires a continuous improvement of the active antenna in terms of operating bandwidth, scanning angle capability, and swath width, thus leading to the demand for increased RF power and better power efficiency of the RF transmitter. Moreover, compact size and light weight are relevant objectives for making the overall SAR instrument appealing for future applications. The transmit/receive module (TRM) shown in this paper was developed while combining all these requirements in a cost-effective approach. A careful design of all relevant RF interconnects and passive devices was performed to ensure the largest output power from the last high-power amplifier of the transmitting chain, the lowest noise figure at the input of the receiving chain, and the calibration capability for appropriately tuning the TX and RX signal. The TRM was manufactured and experimentally tested to verify its performances. The measurement results show the superior performances of the proposed compact high-power large-bandwidth TRM. The achieved target objectives make the design of the proposed TRM readily applicable for the development of a compact, high-power, and highly integrated AESAs to be used for next-generation satellite constellations for Earth observation.