A novel lightweight dual-frequency dual-polarized sixteen-element stacked patch microstrip array antenna for soil-moisture and sea-surface-salinity missions

The main motivation for this paper is to discuss the development of a novel compact and light-weight dual-frequency, dual linearly polarized, high-efficiency, stacked-patch microstrip-array antenna for use in standalone aircraft-based remote sensing applications. Results from simulation, fabrication, and testing of a sixteen-element stacked-patch array antenna, optimized for an L-band frequency of operation, are presented. The design center frequencies were 1.26 GHz and 1.413 GHz with 10 MHz and 25 MHz bandwidths in each band, respectively. Due to the large number of design parameters and demanding design requirements of beam-efficiency, sidelobe levels, and polarization characteristics, particle-swarm optimization (PSO) and finite-difference time-domain (FDTD) simulations were used for synthesis and analysis. Cancellation techniques, based on symmetry, were applied to the antenna ports, with a custom-built feed network to reduce cross polarization. Simulations and measurement results from a spherical near-field test facility confirmed excellent performance of the array configuration, with a beam efficiency of greater than 90%, isolation better than -35 dB, and cross polarization in the main beam of the array better than -40 dB. From the sixteen-element array simulations and experimental verifications, one of the objectives of the present study is to suggest the possibility of using customized dual-frequency, dual-polarized arrays as potential feeds for reflectors to replace the traditionally used conical horns for future soil-moisture and sea-salinity missions     

Noise temperature and gain loss due to paints and primers: a casestudy of DSN antennas

In achieving high performance for reflector antennas, it has been noted that it is essential to carefully assess the roles of surface paints and primers. A thorough literature search has revealed that not much has been reported on this very important engineering-implementation topic. It is one of the main objectives of this feature article to provide a detailed study on the effects of paints and primers on reflector-antenna performance. In particular, as a case study, this paper presents excess-noise-temperature and added-gain loss data at 32 GHz for various combinations of paints and primers currently being studied for use on DSN (Deep Space Network) antenna reflector surfaces. It is shown that 500FHR6 acrylic urethane-based paint has the lowest excess-noise-temperature contribution. Previously, it has been recommended that this paint be used for all new DSN beam-waveguide antennas being constructed, and for all those 34-m and 70-m antennas with reflector surfaces that need repainting. The results, methodologies, and observations presented in this article are also applicable to other reflector-antenna configurations