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A low-profile dual-polarized magneto electric (ME) dipole antenna configuration implemented on standard multilayer PCB technology is here reported. The proposed radiator is conceived for dual-polarized 28 GHz 5G phased array applications. Wideband operation is achieved by applying several low-frequency techniques which allow to fulfil the 5G requirements without increasing the dielectric core thickness. A $4\times8$ ME-dipole phased array is then designed, fabricated, and tested. The measured beam scanning range without the blindness in the E-plane is ±55° for the vertical polarization. Stable radiation patterns and a gain of up to 22 dBi are also achieved. The thickness of the antenna layers is significantly lower with respect to the other configurations in the literature while providing similar performance. Having reduced the antenna core thickness results in a structurally balanced stack-up, lighter and easier to fabricate with high yield. In addition, high isolation between the elements allows superior beam scanning performances. The proposed design is well suited to both packaging technologies and standard PCB processes and is an attractive candidate for the millimeter-wave applications in the fifth generation (5G) mobile systems.

To enhance the capabilities of high-resolution imaging or beamforming, the trend goes towards arrays with high-channel count and large aperture sizes. The operation at increasing mm-wave frequencies exacerbates the consequences of manufacturing tolerances on the array performance, further necessitating the development of high-quality calibrations. Thereby, a large number of array response vectors, addressed in the following as data points, is stored. Typically, one data point is measured at a time for each angle. To reduce the calibration effort, hereby defined as the number of required measurements, a calibration setup employing active calibration targets (ACT) is proposed. This setup allows the storage of a multitude of data points within a single measurement. In addition, this measurement setup is placed in the near-field of the array to relax the requirements on the size of the anechoic chamber. Employing multiple targets makes it challenging to compensate the near-field effects. Therefore, methods are discussed to ensure a consistent quality of the calibration considering the near-field influences from the ACTs. Exemplary measurements deploying an antenna array operating at 78.5 GHz demonstrate that this calibration measurement setup employing three ACTs placed in the near-field of the array reduces the calibration effort by a factor of 3 compared to state-of-the-art setups. The average deviation of the antenna phase relations amounts to 4.1 degree, proving that the presented setup achieves the same calibration quality as state-of-the-art setups.

Distributed phased arrays based on unmanned aerial vehicle (UAV) swarm with small antenna elements on each micro-UAV are expected to achieve much better performance than the traditional phased arrays due to a large amount of swarm mobile individuals and deployment flexibility. To avoid the possible collisions of the flying UAVs, a large separation distance between UAVs is required, but grating lobes can appear when the array element spacing is larger than one-half wavelength. To solve this issue, array antennas with aperiodic element placement are normally used to mitigate the grating lobes, while suffering from a high collision risk for UAVs due to the reduced array element separation in the aperiodic array. This paper proposes a novel 3-D aperiodic array design by adding an additional degree of freedom in the optimization of array configuration. The sidelobe levels can be largely reduced from the planar periodic arrays. In addition, the collision risk for UAVs represented by the minimum separation distance between array elements can be largely decreased from the planar aperiodic arrays. This work provides a feasible strategy for the design and optimization of the UAV swarm-based phased arrays for practical applications.

To overcome the limited payload dedicated to onboard antennas for CubeSat/SmallSat applications, this paper presents a novel, foldable, dual-polarized Tightly Coupled Dipole Array (TCDA). In comparison to previous vertical feeds used for TCDAs, this array integrates a planar microstrip balun feed to enable foldability. The proposed array attains 5.4:1 (0.6-3.20 GHz) impedance bandwidth with VSWR < 3 at broadside and scans down to 45° at all azimuth planes. Notably, a substrate-integrated in-plane folding mechanism based on Lamina Emergent Torsion (LET) joints is employed to achieve foldability coupled with a simple fabrication process. The average simulated radiation efficiency was 95% across the band. A $5\,\, \times8$ prototype array was fabricated and tested to verify the finite array’s foldability, bandwidth, and gain performance. This prototype achieves 80% one-dimensional size reduction, yielding 60% overall volume reduction. Consequently, the array prototype can be folded and stowed in a compact volume of 1.4U (25 cm $ \times7.2$ cm $ \times9$ cm).

A reconfigurable phased array architecture utilizing a two-port half-loop antenna (THLA) is proposed and demonstrated at mmWave spectrum. The polarization, pattern, and beam steering can be freely reconfigured without any changes in the hardware by adjusting the weighting vectors of each port through software control. The proposed concept is demonstrated using an 8 RF port configuration and its isolation, gain, beam pattern, and beam steering resolutions are studied. Afterward, a $2\times 2$ THLA is exemplified as a proof-of-concept prototype for verifying its versatile radiation modes under realistic conditions. A low temperature co-fired ceramic process is applied to demonstrate its compatibility with conventional RF modules. Among the versatile modes of the $2\times 2$ THLA, 23 distinct radiation modes are selected and experimentally verified. The reflection and mutual coupling coefficients of the $2\times 2$ THLA are measured to be less than −10 dB at 28 GHz spectrum. Furthermore, the maximum gain of 8.47 dBi is confirmed at 28 GHz. This is the first to demonstrate a fully reconfigurable antenna which eliminates the need of any external and lumped components applicable for universal mmWave wireless applications.

Within the context of modern digital phased array (DPA) radios, differential Radio Frequency (RF) front-ends provide much greater immunity to noise and distortion by suppressing second order harmonics. Recent advancements in differential RF front-ends offer high dynamic range, high linearity, and low noise in the transceiver chain. However, a major roadblock to fully differential systems is the presence of common-mode resonances. In this article, we present a novel wideband differential feed for dipole arrays that overcomes this bottleneck. Our dipole array is developed for the L-S band (viz. 1.05 GHz to 3.2 GHz) with emphasis on dual-linear polarization and resonance-free scanning to low angles. The novelty of this article is the Balanced Wideband Impedance Transformer (BWIT) feed that mitigates common-mode currents across the entire band while scanning to low angles. Array simulations are verified with measurements of an $8\times 8$ prototype in a volume of 384mmx384mmx57 mm. The array achieves resonance-free scanning across a 3:1 impedance bandwidth with VSWR

Modern phased arrays require large instantaneous bandwidths, wide fields of view, and low profiles to conduct multiple functions. Many of these phased arrays rely on emerging high speed ADCs and advanced balanced transceivers. The benefits of balanced front-ends include improved linearity, dynamic range, isolation, and noise resilience. The application of a differential phased array in such a system removes extraneous losses caused by baluns, though the issue of feed-borne E-plane scan resonances must be considered. We address the E-plane scan resonance issue through an improved Balanced Wideband Impedance Transformer (BWIT) feed for the ultra-wideband (UWB) Tightly Coupled Dipole Array (TCDA). This BWIT feed has already demonstrated mitigated common-modes over a 3:1 bandwidth ratio while scanning to low angles. Here, our differential TCDA (D-TCDA) is developed for the L-C band (viz. 1.0 GHz to 6.1 GHz) with emphasis on resonance-free wide-angle scanning. Rigorous EM model and circuit analysis is included to verify the BWIT performance. Under a VSWR < 3 definition, the improved array achieves a 6:1 impedance bandwidth ratio (BWR) with resonance-free scanning in all planes. An exception is the H-plane scanning at 60° where the VSWR < 4. Array simulations are verified with measurements for an $8\times 8$ single-polarized prototype.

Reconfigurable and deployable antenna arrays are required communications and remote sensing onboard small satellites/CubeSats. There is also a need for packing before launch due to the limited payload space for exo-atmospheric deployments. In this context, origami-based aperture packing and unpacking is relevant and attractive for low-volume storage. However, after several physical morphing cycles, origami apertures may not maintain the performance exhibited by fixed apertures. That is, origami-based antenna arrays are likely to suffer from reduced gain and polarization purity. Therefore, physical effects caused by origami folding should be analytically incorporated into the design. This paper proposes a statistical analysis to study the gain performance of deployable ultra-wideband Miura-ori apertures by including geometrical errors inherent to a partially deployed state. A closed-form expression of the gain degradation is derived and verified using full-wave simulations.

In the upper millimeter wave range above 100 GHz, the effect of array imperfections like manufacturing uncertainties and mutual antenna coupling increases, which leads to deviations from the nominal antenna positions and angle-dependent errors in direction-of-arrival (DoA) estimation. The proposed calibration procedure aims to correct the assumed array response model, based on nominal antenna positions and therefore to improve the measurement accuracy of the array. Typically, the calibration parameters are obtained by interpolating a data set consisting of calibration measurements at known angles. The required number of measurement points in the calibration procedure increases with larger array size, which makes array calibration very time-consuming and costly. In this article, a highly efficient angular array calibration procedure is proposed based on the modal wave expansion technique. After an initial theoretical formulation of the modal wave expansion followed by simulations, it is shown how the limitation of the minimum required number of measurement points in conventional calibration techniques can be eliminated. Experimental results with an antenna array at 150 GHz demonstrate that this novel approach achieves a significant reduction of the number of angular measurement points, especially for large arrays with a high channel count, without degrading the DoA estimation performance.

A wide-band phased array antenna with wide-angle scanning capability for mobile communication system is proposed in this article. An air cavity is properly embedded into the substrate under each array element. This method is very simple and can efficiently enhance wide-angle scanning performance by improving the wide-angle scanning impedance matching (WAIM) and realizing the beam-width of elements in the array. Besides, the operating bandwidth is also extended with the proposed approach. The wide-angle scanning capability is analyzed and verified by both the linear array antennas (on large ground planes in detail) and the planar array. Two $1\times 8$ linear arrays and one $8\times 8$ planar array are demonstrated, which achieve the beam scanning of around ±60° with a realized gain reduction under 3.5 dB in the wide operating bandwidth (37.4%). Furthermore, the beam in the E-plane can scan over ±70° with a realized gain reduction under less than 3 dB. Two linear array prototypes with wide-angle scanning capacity in two planes are fabricated and characterized, yielding good performance within overall operational bandwidth. The measured results align very well with the simulated. The proposed wideband phased array with large scanning coverage is a promising candidate for 5G mobile communications.