This brief presents a novel wideband 90° phase shifter using broadside-coupled microstrip lines (MSLs). Firstly, compared with its traditional counterpart, the proposed one can significantly increase the coupling degree as inquired in the traditional design so as to realize a much wide operating bandwidth in a simple topology. Secondly, for facilitating the design process, this brief introduces a synthesis method to efficiently design the proposed broadband phase shifter with prescribed parameters. Finally, to verify the proposed design, a prototype of the proposed phase shifter is designed, fabricated, and measured. The measured results show that the wideband phase shifter proposed in this brief can achieve 90°±3°, S ₁₁ <−22 dB, and fractional bandwidth (FBW) of 80%.

We propose a synthesis method to design a 90° bent fair circular waveguide TE01 mode transition based on the non-uniform rational B-spline technique. The transition by this method has advantages of small geometry, high transmission with wide band and high profile fairness. An example of design of such a transition is presented. The simulation shows that the transition exhibits a transmission as high as 99.3% at the central frequency 35 GHz and has a bandwidth of 16.7% when keeping the transmission over 95%. Furthermore, the profile is extremely fair, which meets the requirements to decrease the geometry errors between actual device and its design, to reduce the machining difficulty in the machining process. The hot test data indicate that good transmission of the TE01 mode is obtained.

Adaptive beamforming is sensitive to steering vector (SV) and covariance matrix mismatches, especially when the signal of interest (SOI) component exists in the training sequence. In this paper, we present a low-complexity robust adaptive beamforming (RAB) method based on an interference–noise covariance matrix (INCM) reconstruction and SOI SV estimation. First, the proposed method employs the minimum mean square error criterion to construct the blocking matrix. Then, the projection matrix is obtained by projecting the blocking matrix onto the signal subspace of the sample covariance matrix (SCM). The INCM is reconstructed by replacing part of the eigenvector columns of the SCM with the corresponding eigenvectors of the projection matrix. On the other hand, the SOI SV is estimated via the iterative mismatch approximation method. The proposed method only needs to know the priori-knowledge of the array geometry and angular region where the SOI is located. The simulation results showed that the proposed method can deal with multiple types of mismatches, while taking into account both low complexity and high robustness.

The requirements of 5G/6G promote progress in the miniaturization of the antenna array, which promotes the development of a closely spaced decoupling technique. However, the present techniques face the common problem of beam tilt if the spacing is close. Thus, a pattern-corrected, closely-spaced technique is proposed in this paper for the two patch antennas with the λ₀/20 edge-to-edge distance of the H-plane. The corresponding structure, which is inserted at the center of the spacing, consists of a vertical wall with a single substrate and two symmetrical T-type metals, and a slot at the center is reserved to adequately accommodate the vertical wall. The vertical strip at the other end of the T-type metal is connected to the ground of the patch antenna, while the parallel strip is placed exactly above the patch substrate. After an exact analysis, a prototype was fabricated and measured, and the results showed that the measurements agreed well with those of the simulations, the decoupling coefficients in the 5.8 GHz band were below −20 dB, and the measured radiation pattern at 5.81 GHz was corrected to the broadside from 28° and the maximum realized gain was 5.30 dB.

In this paper, two ultra-wideband monopoles in a colinear structure are presented for application in remote terrestrial communication systems. The antennas consist of a loaded monopole with a hat and an elevated loaded monopole located in the upper position. All lumped loads are modeled as linear frequency-dependent components to approximate the practical component property for achieving ultra-wideband characteristics, since the constant value property of a component is only present in a relatively narrow band. The antennas are simulated by the method of moments (MoM) with asymptotic waveform evaluation (AWE) to speed up frequency sweep across a wide bandwidth. For proper simulation with the AWE process, the parallel RLC load with linear frequency-dependent components is modeled in a corresponding impedance function. With the optimized load parameters, one antenna covers 30–750 MHz with a VSWR < 3.5 and the other one covers 800 MHz–3000 MHz with a VSWR < 2.5, which are promising results for terrestrial omnidirectional applications.