A low-cost single-layer wideband microstrip antenna array is presented for 60-GHz band applications. Each microstrip radiation element is fed by a modified L-shaped probe to enhance the impedance bandwidth. The proposed microstrip antenna array is excited by a novel coplanar waveguide (CPW) feed network, which not only has a simple structure by abandoning the traditional air bridges (wire bonds) above the CPW T-junctions but also provides pairs of broadband differential outputs. Experimentally, two 4 $\,\times\,$ 4 antenna arrays with different polarizations were designed and fabricated on the double-sided single-layer printed circuit board. The linearly polarized array exhibits an impedance bandwidth ( ${\hbox{SWR}}\leq 2$ ) of 25.5% and a gain of around 15.2 dBi. The circularly polarized array, employing the same CPW feed network to excite sequentially rotated circularly polarized elements, achieves an impedance bandwidth ( ${\hbox{SWR}}\leq 2$ ) of 17.8%, a 3-dB axial ratio bandwidth of 15.6%, and a gain of around 14.5 dBi.

Low-Cost Wideband Microstrip Antenna Array for 60-GHz Applications

Cavity-backed patch antenna arrays with full corporate substrate integrated waveguide (SIW) feed networks are demonstrated at V-band for applications with the needs of high-gain antennas. A prototype of $16 \times 16$ radiating elements with a waveguide transition is fabricated by applying standard printed circuit board (PCB) facilities. A gain up to 30.1 dBi with a 3-dB gain bandwidth of 16.1%, an impedance bandwidth of 15.3% for $\mathrm{SWR} \,{ , and symmetrically broadside radiation patterns with $-40\,\mathrm{dB}$ cross-polarizations are achieved. The performance of the proposed antenna array is also systematically evaluated. The result serves as a reference for designing large antenna arrays operating at millimeter-wave frequencies.

60-GHz Substrate Integrated Waveguide Fed Cavity-Backed Aperture-Coupled Microstrip Patch Antenna Arrays

A low-cost high-gain and broadband substrate integrated waveguide (SIW)-fed patch antenna array is demonstrated at the 60-GHz band. A single-layered SIW feeding network with wideband T-junctions and wideband high-gain cavity-backed patch antennas are employed to achieve high gain and wideband performance simultaneously. Although the proposed antenna array has a multilayered structure, it can be fabricated by conventional low-cost single-layered printed circuit board (PCB) technology and then realized by stacking and fixing all of single layers together. The simulated and measured impedance bandwidths of a 4 × 4 antenna array are 27.5% and 22.6% for 10 dB. The discrepancy between simulation and measurement is analyzed. A gain up to 19.6 dBi, and symmetrical unidirectional radiation patterns with low cross polarization are also achieved. With advantages of low fabrication cost and good performances, the proposed antenna array is a promising candidate for millimeter-wave wireless communication systems.

Low-Cost High-Gain and Broadband Substrate- Integrated-Waveguide-Fed Patch Antenna Array for 60-GHz Band

Phased-array modules at frequencies >20 GHz are expected to play an important role for 5G applications. Antenna-in-package (AiP) is a reliable and cost-effective method to realize these phased arrays. This paper introduces a practical Ka-band AiP structure and discusses the antenna element design and implementation tradeoffs. The AiP design is based on multilayer organic buildup substrates that are suitable for phased-array module integration needs and supports both horizontal and vertical polarizations. Measurement results from the fabricated antenna prototypes show 0.8 GHz return loss bandwidth and 3.8-dBi peak gain at 30.5 GHz. Simulation results agree with the measured ones.

Antenna-in-Package Design Considerations for Ka-Band 5G Communication Applications

A novel single-fed low-cost wideband and high-gain slotted cavity antenna based on substrate integrated waveguide (SIW) technology using high-order cavity modes is demonstrated in this paper. High-order resonant modes ( ${\text T}{{\text E}_{{130}}}$ , ${\text T}{{\text E}_{{310}}}$ , ${\text T}{{\text E}_{{330}}}$ ) inside the cavity are simply excited by a coaxial probe which is located at the center of the antenna. Energy is coupled out of the cavity by a $3 \times 3$ slot array etched on the top surface of the cavity. Two antennas with different polarizations are designed and tested. Measured results show that the linearly polarized prototype achieves an impedance bandwidth $\left(\vert{{\text S}_{{\text 11}}}\vert of $> {26}\% $ (28 to 36.6 GHz), and a 1-dB gain bandwidth of 14.1% (30.3 to 34.9 GHz). In addition, a measured maximum gain of 13.8 dBi and radiation efficiency of 92% are obtained. To generate circularly polarized radiation, a rotated dipole array is placed in front of the proposed linearly polarized antenna. Measured results show that the circularly polarized antenna exhibits a common bandwidth (10-dB return loss bandwidth, 3-dB axial ratio bandwidth, and 1-dB gain bandwidth) of 11%.

Low-Cost Wideband and High-Gain Slotted Cavity Antenna Using High-Order Modes for Millimeter-Wave Application

A 4 $\,\times\,$ 4 L-probe patch antenna array using multilayer low temperature co-fired ceramic (LTCC) technology is presented for 60-GHz band applications. The proposed antenna array is designed with a high gain in the impedance bandwidth by introducing a novel soft-surface structure. The soft-surface structure comprised of metal strips and via fences reduces the losses caused by severe surface waves and mutual coupling between adjacent elements to improve the radiation performance. The proposed antenna array is convenient for integrated applications. The fabricated antenna array excluding the measurement transition has dimension of 14.4 $\,\times\,$ 14.4 $\,\times\,$ 1 mm $^{3}$ . The simulated and measured impedance and radiation performance are studied and compared. Good agreement is achieved between simulation and measurement. The proposed antenna array shows a wide simulated impedance of 29% from 53 GHz to 71 GHz for $\vert {S}_{11}\vert dB, measured broadband 3-dB gain bandwidth of 18.3% from 54.5 GHz to 65.5 GHz and the gain up to 17.5 dBi at 60 GHz, respectively.

Wideband High-Gain 60-GHz LTCC L-Probe Patch Antenna Array With a Soft Surface

An unconditionally stable finite-difference time-domain (FDTD) method based on the weighted Laguerre polynomials (WLP) for solving Maxwell's equations had been proposed. In this paper, a memory efficient modification to the proposed methodology is described. In this novel modification, the divergence theorem is introduced in the WLP-FDTD method, in which Maxwell's divergence equation replaces one of the curl equations. This leads to a more memory-efficient matrix equation and a more rapid computational speed. A numerical example considering a two dimensional (2-D) TE case is present to validate the efficiency of the proposed algorithm.

A Memory-Efficient Formulation of the Unconditionally Stable FDTD Method for Solving Maxwell's Equations

A compact wideband and wide-scanning planar triangular-lattice phased array is proposed. The proposed element is a U-slot microstrip antenna surrounded by a substrate-integrated cavity (SIC) structure fed by a 50 $\Omega$ coaxial cable. The scan blindness is effectively shifted out of the operation band as the SIC structure obstructs the surface wave and mutual coupling. The proposed array is arranged in a triangular lattice with fewer elements than a rectangular one. A $4\times 8$ planar array prototype is fabricated and measured over $X$ -band. The antenna provides a bandwidth of over 30% frequency range under ±60° scanning in all azimuth planes.

Wideband Wide-Scanning Planar Triangular-Lattice Phased Array With Substrate-Integrated Cavity-Backed U-Slot Patches

A 4×4 L-probe patch antenna array using multilayer low temperature co-fired ceramic (LTCC) technology is presented for V-band applications. The proposed antenna array is designed with high gain and stable peak gain in the wideband impedance bandwidth. A novel soft-surface structure is introduced as the gain enhanced structure to improve the gain performance. The proposed soft-surface structure comprised of metal strips and via fences is used to reduce the losses caused by severe surface waves and mutual coupling between adjacent elements to improve the radiation performance. The fabricated antenna array excluding the measurement transition has dimension of 14.4×14.4×1mm3. Good agreement is achieved between simulated and measured results. The proposed antenna array shows a wide simulated impedance of 29% from 53GHz to 71GHz for |S 11 | < −10dB, and the measured gain up to 17.5dBi at 60GHz, respectively.

A 60-GHz wideband L-probe patch antenna array with gain enhanced structure based on LTCC technology

A novel integration approach is developed for efficiently evaluating double surface integrals in time-domain integral equation formulations. The approach mainly consists of an angular integration scheme for inner 2-D integrals and a modified outer integration scheme. The approach proposed can handle the singularity and near-hypersingularity of the 4-D integrals, and is sufficiently general for arbitrary types of basis functions over planar domains. As several numerical results will demonstrate, the proposed approach has high accuracy and rapid convergence rate for a variety of integral kernels.

Wei-Xing Sheng

Papers

Wideband High-Gain 60-GHz LTCC L-Probe Patch Antenna Array With a Soft Surface

A Memory-Efficient Formulation of the Unconditionally Stable FDTD Method for Solving Maxwell's Equations

Wideband Wide-Scanning Planar Triangular-Lattice Phased Array With Substrate-Integrated Cavity-Backed U-Slot Patches

A 60-GHz wideband L-probe patch antenna array with gain enhanced structure based on LTCC technology

Fast and Accurate Evaluation of Double Surface Integrals in Time-Domain Integral Equation Formulations