Radiation Characteristics of a Microstrip Patch Over an Electromagnetic Bandgap Surface

• Published in: IEEE transactions on antennas and propagation 2007-06, Vol.55 (6), p.1691-1697
• Main Authors: Jing Liang, Yang, H-Y.D.
• Format: Article
• Language: English
• Subjects: Antennas; Applied sciences; Cavity resonators; Couplings; Design engineering; Electromagnetic bandgap (EBG); Electromagnetic radiation; Exact sciences and technology; high-impedance surface (HIS); Joining; Metamaterials; Microstrip antennas; Microstrip lines; microstrip patch antenna; Microstrip resonators; Microstrip transmission lines; Patch antennas; periodic microstrip line; Periodic structures; Photonic band gap; Radiocommunications; Resonance; Resonators; Telecommunications; Telecommunications and information theory
• ISSN: 0018-926X; 1558-2221
• DOI: 10.1109/TAP.2007.898633

Radiation characteristics of a microstrip patch over an electromagnetic bandgap (EBG) substrate are investigated in this paper. This paper focuses on a mushroom-type EBG structure, although the design is applicable to various EBG profiles. The patch antenna is modeled as a half-wavelength resonator of an EBG-loaded microstrip transmission line. Through a full-wave eigenmode analysis of a microstrip line on an EBG structure, it is found that the resonant patch will not see a high-impedance surface (HIS), but rather it is coupled to the EBG structure as an open cavity resonator. Due to strong near-field coupling, the propagation characteristics including the bandgap zones are very different with or without the patch cover. The use of an EBG structure as a bulk material for antennas is seen inappropriate. The EBG surface is found to have the effect of reducing the patch resonant length and bandwidth. A prototype of a microstrip line proximity fed to a patch antenna is fabricated and tested to verify the analysis.