Gain-Equalized Multibeam Antenna Fed by a Compact Dual-Layer Rotman Lens at Ka-Band

Jianping Li, Chong He, Haijun Fan, Ronghong Jin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


This communication presents a gain-equalized $K_{a}$ -band Rotman lens-fed antenna by using phase gradient transmission lines (PGTLs). With PGTLs, the variation trend of the output progressive phase differences among the feeding ports is inverted. The aperture loss of the planar antenna array is then partially compensated by the efficiency of the lens when performing a wide-angle beam scanning. Hence, gain equalization is achieved among multiple beams with an acceptable gain degradation. To reduce the total size, the Rotman lens with PGTLs, the feeding networks, and the antenna array are stacked vertically. Meanwhile, the feeding network is implemented with substrate integrated coaxial lines, suppressing the parallel-plate mode inside the multilayer structure. In order to validate the proposed design, a compact Rotman lens-fed antenna operating at 24.75-27.5 GHz (FBW = 10.5%) is designed and fabricated. The results show that the gain drop of the Rotman lens-fed multibeam antenna is reduced from 4.4 to 1.5 dB at the design frequency of 26 GHz, covering a wide angular range between ±56°.

Original languageEnglish
Pages (from-to)2307-2311
Number of pages5
JournalIEEE Transactions on Antennas and Propagation
Issue number3
Early online date15 Sept 2021
Publication statusPublished - Mar 2022


  • Gain equalization
  • phase gradient transmission lines (PGTLs)
  • Rotman lens-fed antenna
  • substrate integrated coaxial lines (SICLs)

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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