Pattern Synthesis of Dual-band Shared Aperture Interleaved Linear Antenna Arrays

This paper presents an approach to improve the efficiency of an array aperture by interleaving two different arrays in the same aperture area. Two sub-arrays working at different frequencies are interleaved in the same linear aperture area. The available aperture area is efficiently used. The element positions of antenna array are optimized by using Invasive Weed Optimization (IWO) to reduce the peak side lobe level (PSLL) of the radiation pattern. To overcome the shortness of traditional methods which can only fulfill the design of shared aperture antenna array working at the same frequency, this method can achieve the design of dual-band antenna array with wide working frequency range. Simulation results show that the proposed method is feasible and efficient in the synthesis of dual-band shared aperture antenna array

Phased-Array Antenna Calibration and Cross-polarization improvement of an X-band Weather Radar

Modifications and updates to an existing X-band dual-polarization phased-array weather radar. Efforts to improve the polarization isolation of the antenna. Characterization via near-field range and field measurements.Dual-polarized phased-array radars used for weather retrieval purposes is an emerging tendency over the last few years. The dual-polarization technology provides an expanded range of weather products and the reliability of these polarimetric products rely on the beam shape quality of the system under use and its polarization isolation. This thesis presents the calibration process of a one-dimensional scanning phased-array radar to assure its beamforming quality. A cross-polarization cancellation technique, with no additional hardware requirements, is tested and appeared to optimize the array settings for an improved isolation and therefore, for a better data quality.Radares formados por agrupaciones de antenas que trabajan con dos polarizaciones con la intención de tomar medidas meteorológicas es una tendencia a la alza en los últimos años. El hecho de utilizar dos polarizaciones ofrece una gama ampliada de productos meteorológicos y la fiabilidad de estos dependerá de la cualidad del haz radiado por el radar y del aislamiento entre las polarizaciones de éstos. Esta tesis presenta el proceso de calibración de un radar, formado por una agrupación de antenas que escanean en una dimension, con tal de garantir la calidad de los haces producidos. Una técnica para cancelar la polarización no deseada, sin la necesidad de ningún hardware adicional, ha sido probada y ha mostrado que puede mejorar la configuración de la agrupación para obtener una mejora del aislamiento y mejorar así, la cualidad de los datos.Radars formats per agrupacions d’antenes que treballen amb dues polarizations amb l’intenció de mesurar paràmetres meteorològics és una tendencia que va en augment en els últims anys. El fet d’utilitzar dues polarizations ofereix una gama ampliada de productes meteorològics i la fiabilitat d’aquests dependrà de la qualitat que tinguin els feixos radiats pel radar així com de l’aïllament entre les polaritzacions d’aquests. Aquesta tesis presenta el procés de calibració d’un radar, format per una agrupació d’antenes que escanejen en una dimensió, per tal de garantir la qualitat dels feixos produïts. Una tècnica per cancelar la polarització no desitjada, sense la necessitat de hardware adicional, ha estat provada i ha mostrat que pot millorar la configuració de l’agrupació per tal d’obtenir una millora en el l’aïllament i així millorar-ne la qualitat de les dades

New Polarization Basis for Polarimetric Phased Array Weather Radar: Theory and Polarimetric Variables Measurement

A novel scheme is developed for mitigating measurement biases in agile-beam polarimetric phased array weather radar. Based on the orthogonal Huygens source dual-polarized element model, a polarization measurement basis for planar polarimetric phased array radar (PPAR) is proposed. The proposed polarization basis is orthogonal to itself after a 90° rotation along the array’s broadside and can well measure the characteristics of dual-polarized element. With polarimetric measurements being undertaken in this polarization basis, the measurement biases caused by the unsymmetrical projections of dual-polarized element’s fields onto the local horizontal and vertical directions of radiated beam can be mitigated. Polarimetric variables for precipitation estimation and classification are derived from the scattering covariance matrix in horizontal and vertical polarization basis. In addition, the estimates of these parameters based on the time series data acquired with the new polarization basis are also investigated. Finally, autocorrelation methods for both the alternate transmission and simultaneous reception mode and the simultaneous transmission and simultaneous reception mode are developed