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In this article, the design and implementation of a low-loss bidirectional microelectromechanical system (MEMS)-like passive beamformer for emerging millimeter-wave (mm-Wave) applications are illustrated. A 4 $\times $ 4 phased-array antenna (PAA) is fabricated employing the proposed beamformer for demonstration. The phase shifter (PS) embedded in the beamformer operates based on the principle of loaded-transmission line (TL) PSs. Slow wave mechanism is employed to shrink the size of the PS. The PS measurement results show the average insertion loss (IL) of 1.3 dB in all the tuning states and the IL variation is 0.9 dB. The PS provides 380° of the phase tuning range in a compact footprint area of 2.4 mm $\times $ 3 mm. The antenna array incorporates slot-coupled patch antennas with left-handed circularly polarized (LHCP) radiation. The operating frequency bandwidth of the antenna system ranges from 28 to 30 GHz to provide co-pol/X-pol discrimination of more than 12 dB for all the steering angles. Measurement results show the beam steering angular range of ± 30° in both elevation and azimuth planes. The measurement results also show the peak directivity of 18.48 dBic and the radiation efficiency of 58% at boresight at the frequency of 29 GHz. The efficiency drops 16% when the steering angle reaches the maximum. [ABSTRACT FROM AUTHOR]

A low-cost and low-profile $Ka$ -band passive phased-array antenna (PAA) using continuously tunable substrate-integrated waveguide (SIW) phase shifter is presented in this article. The phase shifting mechanism is based on perturbing the electric field of the slotted SIW (SSIW) line by putting a high dielectric constant slab over the slot of SIW. A systematic approach based on a simple transmission line (TL) circuit model which can support different modes is developed as a fast method for design optimization. It provides insightful physical understanding of the operating mechanism of the proposed phase shifter. In addition, a fully verified TL model of the $1\times 4$ SIW PAA is presented and used to predict and optimize the overall reflection coefficients and radiation patterns at different scanning angles. The TL circuit model is verified by full-wave simulations. As a design example, a $1\times 4$ SIW-based phased-array is designed, fabricated, and measured to validate phase shifter performance and capabilities. The prototype exhibits a continuous beam scanning range from −20° to +20° covering the whole operating band of 29–31 GHz. [ABSTRACT FROM AUTHOR]

This letter presents a low-cost, low-profile, and high-performance $Ka$ -band continuously tunable substrate integrated waveguide (SIW) phase shifter. The proposed phase shifter consists of a slot cut on the SIW’s broad wall and a high dielectric constant slab over the slot. The phase-shifting mechanism is based on perturbing the electric field of the SIW’s fundamental mode, TE10-like, by putting a high dielectric constant slab over the slot of SIW structure to create slow wave phenomena. A prototype is designed, fabricated, and measured. The fabricated phase shifter exhibits linear phase–frequency response behavior with an average insertion loss less than 1.5 dB with an insertion loss variation less than 0.5 dB over a phase shift range of 275° in the operating frequency band (29–31 GHz). The phase shifter consumes a maximum of 25-mW power. [ABSTRACT FROM AUTHOR]

This article presents a new class of tunable passive two-way phase shifters, which can provide an arbitrary phase shift ratio at two different transmit and receive frequencies ($f_{T}$ and $f_{R}$) simultaneously. The proposed phase shifter uses one control element to control both paths. This architecture consists of two transmit and receive paths and a high dielectric constant slab over the paths. By properly setting the length ratio between transmit and receive lines under the dielectric slab, the proposed phase shifters can realize any arbitrary phase shift ratio. For fast and accurate modeling of the proposed phase shifter, a simple Transmission Line (TL) circuit model is presented in this article and verified by full-wave simulations and measurement. The model can be used for calculating the reflection coefficient and phase shift. In order to prove the concept, two phase shifters, one with equal phase shift ($\Phi _{T}/\Phi _{R}=1$) and the other with the phase shift is equal to the ratio transmit frequency and receive frequency ($\Phi _{T}/\Phi _{R}=f_{T}/f_{R}$), are designed, fabricated, and measured. All results show very good agreement between the proposed TL model, the full-wave solver, and measurement results. This type of phase shifter can be used for many beam-forming antenna systems, such as interleaved arrays, full-duplex arrays, and multiband arrays. [ABSTRACT FROM AUTHOR]

This paper presents a low-profile, high-performance, and low-cost Ka-band circularly polarized (CP) passive phased-array antenna (PAA) system. A $1\times 4$ passive subarray operating at the Ka-band frequency band is investigated, developed, and tested as a possible building block for mobile satellite communication systems. In particular, a CP antenna integrated with a high-performance passive phase shifter is presented and experimentally verified. A new low-cost and low-profile magnetic actuator is proposed to precisely control the phase state of the phase shifter. A 3-D printed polymer package is utilized to enclose the phase shifter and reduce the environmental effects. The proposed CP passive PAA achieves high-performance right-hand CP radiation with high cross-polarization discrimination over a wide scan angle from 0° to ±38° over the frequency band (29.5–30.5 GHz). An axial ratio (AR) < 3 dB is demonstrated over the entire scanning range. Moreover, the measured radiation efficiency is 60% at boresight. The gain drops by 1 dB at ±38° scanning angles. [ABSTRACT FROM AUTHOR]

A highly efficient millimeter-wave (mmW)/Terahertz (THz) dielectric antenna is proposed. The proposed suspended tapered antenna [made of high resistivity silicon (Si)] is fabricated in a new mmW/THz integrated technology platform called silicon-on-glass (SOG). The fabrication process makes the tapered antenna with deep reactive ion etching of the Si layer of the SOG platform, wherein a part of the glass substrate below the antenna tapered section is etched. The glass substrate below the antenna is etched in hydrofluoric acid (HF 49%) before bonding to the Si wafer. The antenna is designed to radiate both E_x- and E_y-polarizations over the frequency band of 110–130 GHz and features additional advantages including highly linear polarization, high-directivity, integrability, and low-cost fabrication. Numerical and experimental results are presented to validate the high-performance proposed antenna. Experiments show gains of 17.5 dBi at 115 GHz and 18.3 dBi at 128 GHz for E_x^11- and E_y^11-modes excitations, respectively. These two polarizations show measured efficiencies of 94% and 99%, respectively. [ABSTRACT FROM PUBLISHER]

This paper proposes a compact, low-loss, and low cost phase shifter for millimeter-wave phased array systems. The basic idea is to modify the propagation mode of a coplanar waveguide (CPW) by placing a high dielectric constant (40< \varepsilon r < 170) slab on top of it. The phase shift is varied by changing the air gap between the CPW line and the dielectric slab. A piezoelectric transducer has been used to control this air gap precisely. For fast but accurate modeling of the proposed phase shifter, two methods one based on spectral domain analysis and the other based on the conformal mapping have been developed and verified with full wave simulations and measurements. A prototype structure with the operational frequency range from 20 to 40 GHz is presented. The maximum phase shift obtained for the electrically controlled version at 40 GHz is 103 ^\circ with loss variation of 0.2 dB. The total length is 2 mm. [ABSTRACT FROM PUBLISHER]