A Low-Profile Dual-Band Dual-Polarized Quasi-Endfire Phased Array for mmWave 5G Smartphones

Abstract

This paper presents a very low-profile (0.105λ 0 at 28 GHz) dual-band dual-polarized millimeter-wave phased array for 5G smartphones. The array element is based on two distinct dual-band antennas to realize two orthogonal linear polarizations. A planar folded dipole with a parasitic strip is used to produce horizontally polarized radiation, and a novel hexagonal bridge antenna is devised to generate vertically polarized radiation while maintaining a very low profile. A prototype of a 1 × 4 phased array is designed and implemented on a multilayer laminate using standard printed circuit board process. The real estate of the array is kept within 6.5 mm × 23 mm × 1.12 mm. For both polarizations, the −10 dB bandwidth covers 25.4-30.84 GHz and 38-40 GHz with peak gains of 11.31 and 11.93 dBi at two center frequencies, respectively. The overlapped 3 dB scan ranges between both polarizations are ±45 • at 28 GHz and ±39 • at 39 GHz. This work considers a number of important design challenges of implementing low-cost mmWave antennas in smartphones, providing a practical solution to mmWave 5G mobile devices.

A Near-Field-Based Gain and Pattern Measurement Technique for Probe-Fed Millimeter-Wave Antennas [Measurements Corner]

“…For demonstration purposes, two 28-GHz antennas are fabricated and then tested using the NF-to-FF method. The first antenna is a horizontally polarized tapered slot antenna [27], and the second one is a vertically polarized hexagonal bridge antenna [18].…”

“…The second example is the vertically polarized hexagonal bridge antenna reported in [18]. The antenna is fabricated on a multilayer RO4003C substrate w ith a total height of 1.12 mm.…”

“…The antenna geometry and measured reflection coefficients are adapted from the original article and presented in Figure 12 for the reader's convenience. In [18], the NF measurements are used only to determine the normalized radiation patterns of the antenna. The image method is used to obtain the absolute gain.…”

“…The image method is used to obtain the absolute gain. Here we use the NF comparison method to characterize the gain of the antenna and compare the result with the value reported in [18].…”

“…On the other hand, in the proposed NF-to-FF method, the superposition is performed on the calibrated complex NF data of each element, which can be precisely measured using the very NF scan system. In our recent work [18], it is demonstrated that the proposed method is able to characterize the radiation performance of a 1 × 4 phased array with high-level accuracy.…”