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Multistatic radar is a promising option for the low-cost collection of multiple-Doppler weather observations. However, due to the use of low-directivity antennas at the receivers in these systems, they typically suffer from extremely high two-way sidelobe levels compared to monostatic radars. Doppler velocity estimation biases induced by sidelobe contamination have proved to be a significant obstacle to more widespread adoption of this technology. It has been noted in the existing literature that the technique of sidelobe whitening, first developed for use in monostatic systems, has the potential to mitigate this issue. However, the existing sidelobe whitening algorithm is not suitable for use in this application, as it is only capable of achieving whitening in the two-way antenna pattern, whereas an algorithm to be used in the multistatic case must be able to achieve this result in the transmit pattern alone. This article proposes an alternate sidelobe whitening technique based on the method of alternating projections which allows for effective whitening in the one-way antenna pattern. A multistatic weather radar time-series simulator is used in conjunction with numerical weather prediction data to demonstrate the effectiveness of this method in mitigating multiple-Doppler measurement biases. [ABSTRACT FROM AUTHOR]

This contribution presents the results of a dual-polarized radiating element designed to achieve low cross-polarization (lower than −40 dB measured for the E-and H-plane, at least −30 dB in the D-plane based on simulations) and large fractional bandwidth (18%) over wide scanning angles (±60°). The proposed design includes multiple features that enable high isolation between ports, reduction of spurious radiation, highly symmetrical radiated fields, and suppression of diffracted fields between contiguous subarray gaps. To verify the polarimetric requirements for a weather radar, simulated and measured results, including electronic scanning of the array and embedded element patterns of the antenna, are shown. [ABSTRACT FROM AUTHOR]

Spectral regrowth and waveform distortion caused by wideband signals input into active phased array antenna systems is the problem this paper addresses. The paper's unique contribution is the development of the impedance-dependent memory polynomial model, capable of solving nonlinear predistortion model parameters for a solid-state high power amplifier with varying load impedance resulting from active electronic beamsteering. Wideband load impedance mismatched tests demonstrate the effectiveness of this technique on a 2.7 GHz, 8 W amplifier. [ABSTRACT FROM PUBLISHER]

Future weather radar systems will need to provide rapid updates within a flexible multifunctional overall radar network. This naturally leads to the use of electronically scanned phased array antennas. However, the traditional multifaced planar antenna approaches suffer from having radiation patterns that are variant in both beam shape and polarization as a function of electronic scan angle; even with practically challenging angle-dependent polarization correction, this places limitations on how accurately weather can be measured. A cylindrical array with commutated beams, on the other hand, can theoretically provide patterns that are invariant with respect to azimuth scanning with very pure polarizations. This paper summarizes recent measurements of the cylindrical polarimetric phased array radar demonstrator, a system designed to explore the benefits and limitations of a cylindrical array approach to these future weather radar applications. [ABSTRACT FROM PUBLISHER]

As active electronically steerable arrays become more prominent, a new paradigm of assigning bits to a set of digital phase shifters, necessary for analog and digital beamforming, is proposed. It is well known that a modern day digital phase shifter which is associated with each transmit/receive module typically relies on three to seven bits. Each of these phase shifters provide a desired resolution of 45^\circ to 2.8125^\circ, respectively. When an array is steered with a fixed precision set of phase shifters, there are some angles where results are significantly better than others. For example, six bit phase shifters can provide exact 11.25^\circdifferential phases in a linear array, but not 15^\circ, and subsequent quantization errors lead to reduced pointing accuracy and increased sidelobe levels. However, these errors can be minimized if the set of shifters operate collectively instead of independently with “blind” quantization. In particular this study seeks the solution for the following problem: for a set of N phase shifters, each defined by B bits, determine the optimal way to distribute the N\times B bits so that the array performance is maximized. [ABSTRACT FROM PUBLISHER]