Compact, Low-Profile, Linearly and Circularly Polarized Filtennas Enabled with Custom-Designed Feed-Probe Structures

Ming Chun Tang, Dajiang Li, Yang Wang, Kun Zhi Hu, Richard W. Ziolkowski

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


Compact, low-profile, linearly polarized (LP), and circularly polarized (CP) patch-based filtennas are realized with a custom-designed coupling probe. It introduces a deep null at both the lower and upper band edges of the filter response. These two nulls facilitate a quasi-elliptic bandpass behavior and can be independently controlled to achieve sharp band-edge skirts and high out-of-band suppression levels. The CP version evolves from the LP design by introducing a T-shaped near-field resonant parasitic (NFRP) element near the probe to create two transmission paths with an inherent 90° phase difference. Its presence facilitates the simultaneous excitation of the TM10 and TM01 modes of the patch without the need for any power divider or phase delay line, reducing the design complexity and lowering the insertion loss. Prototypes were fabricated, assembled, and tested. The measured results agree well with their simulated values. They are low profile (0.03 \lambda _{0} height) and compact in size ( 0.04~\lambda _{0}^{2} footprint). The LP and CP prototypes exhibit, respectively, a -10-dB fractional impedance bandwidth of 7% and an overlapping axial ratio fractional bandwidth of 4.5%. Excellent measured performance characteristics are demonstrated, including flat passband realized gain values and filter responses with sharp roll-off rates and high out-of-band suppression levels.

Original languageEnglish (US)
Article number9049344
Pages (from-to)5247-5256
Number of pages10
JournalIEEE Transactions on Antennas and Propagation
Issue number7
StatePublished - Jul 2020


  • Circularly polarized (CP) antennas
  • compact antennas
  • filtennas
  • linearly polarized (LP) antennas
  • low-profile antennas
  • near-field resonant parasitic (NFRP) elements

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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