A dual-band, Tx/Rx, self-diplexing phased array is presented. The antenna has been designed to cover Tx/Rx satellite communications at K/Ka band with a frequency ratio 1.5:1. To obtain dual-band operations with a single radiating surface, a novel dual-band radiator is adopted and placed in a configuration in which dual-band and single-band elements are interleaved. The proposed configuration reduces the number of radiating elements required by other solutions while avoiding the insurgence of grating lobes. The tightly packed arrangement of the elements poses many integration issues, which are solved with a novel integration technique. The array elements are optimized to scan the beam in excess of 50° in both bands. A subarray with 49 Rx elements and 105 Tx elements was built and measured confirming the results obtained in simulations.

Satellite, fifth generation (5G), and sixth generation (6G) mobile communication systems operating at micro- and millimeter wave frequencies are an essential pillar in advanced network architectures for high-throughput low latency services. The decisive factors for this current development were the significant technological advances accomplished over the last two decades, which meanwhile enable highly integrated, feature-rich, and cost-effective realizations of complete phased array transceiver topologies. Motivated through the today's trend for heterogeneous constellation types to provide truly global coverage, this contribution reviews the current state-of-the-art of electronically steerable antennas for terrestrial and non-terrestrial communication systems up to 100 GHz. First, the potential benefits and limitations of the most relevant technologies are contrasted and put into context with recent system architectures for adaptive beamforming. Their operating principles along with various experimental implementation and achievements providing advanced capabilities such as multi-band/multi-beam operation, polarization agility, and wide-angle scanning are thoroughly presented. Particular emphasis is laid on the review of direct radiating arrays, quasi-optical antenna configurations, and metasurface-based antennas.

A Polarization Rotator based on Substrate Integrated Waveguide (SIW) is proposed in this paper. The rotator is designed as a dual band, single layer, Frequency Selective Surface (FSS) that transmits a wave rotated of 90-degree with respect to the incident one in one of the two bands maintaining unchanged the polarization in the other one. Other than the design and characterization of the rotator, its application to a linear-to-circular dual band polarizer is also investigated. To this purpose, the rotator is coupled to a conventional meander line polarizer generating orthogonal circular polarizations (CP) in the two bands. This configuration is useful in SatCom applications where the required high isolation between TX and RX channels is obtained assigning orthogonal polarizations to the two bands. As a design example, a prototype is designed and experimentally validated in the SatCom K/Ka-bands. Measured performance shows an isolation between the TX and RX channels of more than 35 dB and insertion losses which do not exceed 1.5 dB in the two operating bands.

The first millimeter-wave system-on-chip for dual-band phased array applications is presented as a proof of concept for K-/Ka-band (20/30 GHz) satellite communication on-the-move applications. Each chip includes four transmit (Tx) and two receive (Rx) channels working at Kaand K-band, respectively. The proposed architecture enables a half-duplex operating mode in two different bands. Its development was driven taking into account the integration into a realistic Tx/Rx shared aperture phased array architecture. Full amplitude and phase control are provided for each channel with high granularity (65536 states). The measured results demonstrate the validity of the proposed chip architecture, even though the channel output power and the noise figure (NF) are not in full agreement with the simulations. In Tx mode, the channel provides 9.47 dB of gain with 4.19-dBm output power at 1-dB compression. In Rx mode, the channel gain is 21.6 dB with an NF of 5 dB. In a scenario with 5.265° phase steps and 8-dB amplitude tapering capability, the amplitude and phase root-mean-square (RMS) errors within the Tx bandwidth (29.5-30.8 GHz) are equal to 0.52 dB and 3.74°, respectively. The amplitude and phase RMS errors in the Rx bandwidth (19.7-21 GHz) are equal to 2.05 dB and 12.11°, respectively. The chip consumes 340 mW in Tx and 242 mW in Rx mode and occupies 3.3 × 3.5 mm ² .

This paper presents a digital beamforming (DBF) synthetic aperture radar (SAR) for future spaceborne earth observation systems. The objective of the DBF-SAR system is to achieve a low cost, lightweight, low-power consumption, and dual-band (X/Ka) dual-polarized module for the next-generation spaceborne SAR system in Europe. The architectures and modules of the proposed DBF-SAR system are designed according to a realistic mission scenario, which is compatible with the future small/microsatellites platforms. This system fills an important gap in the conception of the future DBF-SAR, facilitating a high level of integration and complexity reduction. The proposed system is considered not only the first demonstrator of a receive-only spaceborne DBF system, but also the first X/Ka-band dual-polarized SAR system with shared aperture. This paper presents a description of the proposed instrument hardware and first experimental validations. The concept and design of the DBF multistatic SAR system are discussed and presented first, followed by the design of subsystems such as DBF networks, microwave integrated circuit, and antennas. Simulated and measured results of the subsystems are presented, demonstrating that the proposed SAR instrument architecture is well-suited for the future SAR applications.

In this work, a new dual-band dual-polarized transmitarray antenna element based on multilayer frequency selective surfaces is introduced. This novel configuration has been successfully tested for K/Ka SatCom frequency bands and is composed of a single low-profile printed circuit board incorporating 5 metal layers without any vertical transitional elements. In contrast to existing solutions, this proposal eliminates the need for vertical interconnections, air gaps, or spacers between the metal layers, resulting in a cost-effective board with an overall thickness of 0.24λ ₀ at 30 GHz. The proposed unit cell operates at 20 and 30 GHz exploiting an interleaved lattice configuration. It affords independent control of the transmitted field phase within a range of 300 degrees, at both frequency bands, while maintaining a transmission loss not exceeding 3.5 dB. To substantiate the proposed design, an 87×87mm ² transmitarray has been prototyped and experimentally validated. The measured results indicate a peak gain of 20.6 and 22.8 dBi at 20 and 30 GHz, respectively. Furthermore, the -1dB gain bandwidth has been found to be 5% in the first band and 4.5% in the second band.