A novel design, fabrication, and packaging technology is proposed for liquid crystal (LC)-based beam-scanning leaky-wave antennas (LWAs). Different from conventional ones, extra dispersion sensitivity enhancement (DSE) components are introduced to increase the slope of effective phase constant versus frequency of LWAs and, hence, the beam scanning range. CST MW Studio software package is used to validate the design method. It is shown that, by adding the DSE components, the electrical beam scanning range is extended by more than 56% in the Ku satellite communication band, where good impedance matching and balanced condition are kept for both extreme tuning states of LCs. Prototypes of the designed LC-composite right/left-handed LWAs with and without the DSE components are fabricated and measured. The fabrication methodology incorporating printed circuit board and precision metal processing technology ensures the mechanical stability, flexible design, perfect packaging, and low cost. Finally, the feature-selective validation technique validates that the measured and simulated results are in good agreement.

In this study, a dual-tuned mode of liquid crystal (LC) material was proposed and adopted on reconfigurable metamaterial antennas to expand the fixed-frequency beam-steering range. The novel dual-tuned mode of the LC is composed of double LC layers combined with composite right/left-handed (CRLH) transmission line theory. Through a multi-separated metal layer, the double LC layers can be loaded with controllable bias voltage independently. Therefore, the LC material exhibits four extreme states, among which the permittivity of LC can be varied linearly. On the strength of the dual-tuned mode of LC, a CRLH unit cell is elaborately designed on three-layer substrates with balanced dispersion values under arbitrary LC state. Then five CRLH unit cells are cascaded to form an electronically controlled beam-steering CRLH metamaterial antenna on a downlink Ku satellite communication band with dual-tuned characteristics. The simulated results demonstrate that the metamaterial antenna features’ continuous electronic beam-steering capacity from broadside to −35° at 14.4 GHz. Furthermore, the beam-steering properties are implemented in a broad frequency band from 13.8 GHz to 17 GHz, with good impedance matching. The proposed dual-tuned mode can make the regulation of LC material more flexible and enlarge the beam-steering range simultaneously.

The estimation of direction of arrival (DOA) is paramount in the realm of practical array signal processing systems. Nevertheless, traditional estimation methods often rely heavily on the Gaussian noise assumption, rendering them ineffective in achieving high-precision estimates in environments plagued by strong impulsive noise. To address this challenge, this paper introduces a novel DOA estimation algorithm that leverages mixed fractional lower-order correntropy (MFLOCR) in the context of Alpha-stable distributed impulsive noise. Correntropy is used as a measure of the similarity of the signals, using a Gaussian function to smooth extreme values and provide greater robustness against impulsive noise. By utilizing diverse kernel lengths to jointly regulate the kernel function, the concept of correntropy is expanded and implemented in the fractional lower-order moment (FLOM) algorithm for received signals. Subsequently, the MFLOCR is derived by adjusting the resulting form of correntropy. Finally, an enhanced DOA estimation algorithm is proposed that combines the MFLOCR operator with the MUSIC algorithm, specifically tailored for impulsive noise environments. Furthermore, a proof of boundedness is provided to validate the effectiveness of the proposed approach in such noisy conditions. Simulation experiments confirmed that the proposed method outperforms existing DOA estimation methods in the context of intense impulsive noise, a low generalized signal-to-noise ratio (GSNR), and a smaller number of snapshots.

Partially impaired sensor arrays pose a significant challenge in accurately estimating signal parameters. The occurrence of bad data is highly probable, resulting in random loss of source information and substantial performance degradation in parameter estimation. In this paper, a tensor variational sparse Bayesian learning (TVSBL) method is proposed for the estimate of direction of arrival (DOA) and polarization parameters jointly based on a conformal polarization sensitive array (CPSA), taking into account scenarios with the partially impaired sensor array. First, a sparse tensor-based received data model is developed for CPSAs that incorporates bad data. Then, a column vector detection method is proposed to diagnose the positions of the impaired sensors. In scenarios involving partially impaired sensor arrays, a low-rank matrix completion method is employed to recover the random loss of signal information. Finally, variational sparse Bayesian learning (VSBL) and minimum eigenvector methods are utilized sequentially to obtain the DOA and polarization parameters estimation, successively. Furthermore, the Cramér-Rao bound is given for the proposed method. Simulation results validated the effectiveness of the proposed method.

A dual-beam continuous-scanning spoof surface plasmon polariton (SSPP) leaky-wave antenna (LWA) with synergistic phase-reversal modulation and broadside radiation stabilization is proposed and experimentally validated. The antenna is built on a composite SSPP guiding unit composed of T-shaped resonator elements and semi-elliptical patches, which provides SSPP-type slow-wave guidance and supports spatial-harmonic radiation. Periodic phase reversal is introduced to excite the target −1st spatial harmonic and alleviate the open-stopband (OSB) effect caused by Bragg-reflection accumulation near broadside. Different from an isolated radiating patch, the semi-elliptical patch is incorporated as part of the composite SSPP unit and participates in the modal and dispersion behavior. Owing to its relatively weaker field confinement, it further facilitates residual broadside energy leakage and stabilizes the radiation response. As a result, broadside-stable dual-beam continuous scanning is achieved without an obvious gain dip around broadside. The fabricated prototype scans continuously from −90° to 48° over 5.61–7.84 GHz, with a scanning rate of 4.16°/% and an average gain of 10.6 dBi. The measured results agree well with simulations.