This paper presents the study of a microstrip antenna to be installed onto meteorological nano-satellites. In order to increase the effective ground plane and to optimize the decoupling between the main and the cross polarizations, metallic strips were attached to the antenna ground plane. The antenna performance was evaluated using different types and sizes of metallic strips. An improvement in the front-to-back ratio whilst keeping good axial ratio performance was observed.
This article presents the design and tests of a closed‐loop controlled microwave beamformer for phased arrays. The proposed circuit owns an internal reference signal used to automatically set predefined amplitudes and phases of the beamformer branches. This signal is applied to the branches through directional couplers with high directivity and propagates in them similar to the actual signals coming from the antenna array. As a consequence of this architecture, we found that the impedance mismatch between the antennas and the beamformer as well as the mutual coupling in the array is taken into account during calibration, resulting in a more accurate adjustment of amplitudes and phases. In this work, the influence of the mutual coupling between the antennas and the directivity of the couplers on the beamforming calibration uncertainty is also analyzed. From the derived uncertainties, the corresponding pattern degradation is evaluated by performing Monte Carlo simulations. It is shown that using couplers with low directivity together with tightly coupled arrays can produce undesirable main lobe squints of up to 4.5°, main lobe level deviations of up to 4.2 dB, and side lobe level variations of up to 24 dB. On the other hand, the use of high directivity couplers can mitigate these problems. Lastly, the validation of the designed circuit is conducted in two stages: bench tests and measurements in an anechoic chamber with an array of six printed monopoles operating at 2.2 GHz. Amplitude and phase calibration errors less than 0.5 dB and 3°, respectively, were observed in the bench tests.
Resumo-Este artigo apresenta o projeto de uma topologia de transceptor de frequências para integração em nanossatélites. O objetivoé propor um circuito que receba o sinal, no canal de subida, em 401 MHz e o retransmita no canal de descida em 2,26 GHz. O artigo apresenta análise das seguintes questões: cenário de operação do nanossatélite, dimensionamento dos blocos do sistema e caracterização dos componentes.
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.