Size reduction of microstrip patch antennas with left-handed transmission line loading

• Published in: IET microwaves, antennas & propagation Vol. 1; no. 1; p. 39
• Main Authors: Rajab, K Z, Mittra, R, Lanagan, M T
• Format: Journal Article
• Language: English
• Published: Stevenage The Institution of Engineering & Technology 01.02.2007
• Subjects: Antennas; Ceramics; Finite difference method; Mathematical analysis; Microwave antennas; Patch antennas; Resonant frequencies; Simulation
• ISSN: 1751-8725; 1751-8733
• DOI: 10.1049/iet-map:20050334

A procedure for designing an electrically small microstrip patch antenna (MPA) is developed, wherein the length of a side of the MPA is reduced to significantly less than a half-wavelength. The field distribution in the loaded MPA remains relatively unperturbed, unlike the (0) mode case that attempts to decrease the size by introducing a shorting-post; consequently, very low cross-polarisation behaviour is observed. The theory to predict the full spectrum of resonant frequencies of the antenna is developed, with finite-difference time-domain simulations used to finalise the antenna design. Finally, an electrically small ((λ/6) x (λ/4)) and thin (<lλ/65) antenna is fabricated at 465 MHz using low-temperature co-fired ceramic technology and tested for key figures of merit, including the resonant frequency and radiation pattern. The shortened antenna not only shows performance comparable to a conventional unloaded MPA, but also exhibits good cross-polarisation. The loaded MPA achieved an area reduction of 83% as compared to an unloaded version.