Wideband Transmitarray With Reduced Profile

Qi Luo,Mohammed Sobhy,Xuexia Yang,Steven Gao

doi:10.1109/lawp.2018.2794605

Qi Luo, Mohammed Sobhy + Show 2 more

Open Access

https://doi.org/10.1109/lawp.2018.2794605

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Abstract

This letter presents a wideband transmitarray (TA) with reduced profile. A novel unit cell based on a wideband bandpass filter is developed and applied to the design of the TA. The TA consists of two identical trilayer frequency selective surfaces (FSSs), thus it has a lower profile compared to traditional designs that use at least four FSS layers separated by quarter-wavelength air gaps to obtain the 360° phase shift range. The FSS has a pair of square patches printed on the top and bottom layers, and a square slot loaded by four microstrip lines printed on the middle layer. The phase shift is achieved by simultaneously adjusting the size of the square patches. Within the frequency band of interest, the developed unit cell shows low insertion loss and sufficient phase shift range. An equivalent circuit model is developed to better understand the operating principles of the FSS. To validate the design concept, one prototype operating at 13.5 GHz is designed, fabricated, and measured. The measurement results show that the designed TA achieves 16% 1 dB gain bandwidth and 60% aperture efficiency. The developed unit cell has symmetric configurations so it can also be applied to the design of dual-polarized or circularly polarized TAs.

Highlights

H IGH-GAIN, wideband, and lightweight antennas are highly desirable for many wireless systems, such as satellite communications [1]
The TA unit cell consists of two such frequency selective surfaces (FSSs) separated by a quarter-wavelength air gap, and by using this unit cell, a wideband TA with a reduced profile and high efficiency operating at 13.5 GHz was designed, fabricated, and measured
Another reason is that the feed antenna has higher spillover than the simulation, which is caused by the inaccuracy of the simulation

Summary

INTRODUCTION

H IGH-GAIN, wideband, and lightweight antennas are highly desirable for many wireless systems, such as satellite communications [1]. There is an approximately quarter-wavelength air gap, and the total thickness of this TA is 0.76λ Another wideband TA using similar configuration was reported in [9], which uses four conductive layers printed on four substrates spaced by air gaps to obtain the 360◦ phase shift range. There are several reported works on reducing the profile of the FSS-based TA designs while maintaining the 360◦ phase shift range of the unit cell. The TA unit cell consists of two such FSSs separated by a quarter-wavelength air gap, and by using this unit cell, a wideband TA with a reduced profile and high efficiency operating at 13.5 GHz was designed, fabricated, and measured. Similar gain bandwidth [8], [9], the presented design reduces the profile to 0.36λ while maintaining the wideband operation with promising aperture efficiency.

DESIGN OF THE TA UNIT CELL

DESIGN OF THE TA AND EXPERIMENTAL RESULTS

CONCLUSION