The paper presents a two-phase state based multi-beam-switching scheme implemented on a customdesigned 4 × 4 antenna array operating with a bandwidth of 1.5 GHz around 14 GHz. The antenna array and the beam-switching scheme have been experimentally validated. A phasing network designed to produce two phase states is used to experimentally validate the beam-switching and five beam states are presented, though this can be extended to other configurations using the split beam as a building block to construct multiple beams. The antenna can find potential use in multiuser millimetre-wave massive MIMO scenarios which require simultaneous multiple beams along selective directions.
This letter presents the design and experimental characterization of a K-band high power amplifier (HPA) monolithic microwave-integrated circuit (MMIC) for the next generation of very high throughput satellites (vHTS). The MMIC is a three-stage balanced amplifier realized on a commercial 100-nm gate length gallium nitride on silicon (GaN-Si) technology. The design is compliant with space reliability constraints and, despite the larger thermal resistance and losses shown by the silicon (Si) substrate with respect to the more common silicon carbide (SiC), the realized HPA delivers, in pulsed condition, a peak output power larger than 41 dBm in the operative band from 17.3 to 20.2 GHz, with an associated power added efficiency (PAE) and gain up to 40% and 26 dB, respectively. In continuous wave (CW) operative conditions and with a backside temperature of 85 • C, the MMIC delivers a minimum output power and PAE of 39.4 dBm and 28%, respectively. Moreover, a 24-h test at saturated power has shown almost negligible performance degradations, thus providing confidence in the selected GaN-Si technology's robustness. Index Terms-Gallium nitride (GaN), GaN on silicon (GaN-Si), high power amplifier (HPA), K a-band, satcom.
An overview about some of the recent Spanish developments on active reflectors is presented. In the first part, a novel beamsteering active reflectarray is deeply studied. It is based on implementing in each elementary radiator an IQ modulator structure, in which amplitude and phase control of the scattered field is achieved. Finally, a special effort is made in offering solutions to overcome the active antenna integration problems. In the second part, the active concept is firstly extended to Fresnel reflectors. Thanks to the development of a proper simulator, this special structure can be easily analysed. This simulator allows the study of performance of this kind of reflectors and, applying evolutionary algorithms, to find optimal configurations of reflector in accordance with the given specifications for the conformal radiation pattern.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.