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

K. Z. Rajab, R. Mittra, M. T. Lanagan

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


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 MPA is loaded with a resonant circuit equivalent to that of a left-handed transmission line to artificially increase the effective wavelength of the device, thus creating a resonance equivalent to, but at a lower frequency than the unloaded {10} mode. 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)×(λ/4)) and thin (<λ/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.

Original languageEnglish (US)
Pages (from-to)39-44
Number of pages6
JournalIET Microwaves, Antennas and Propagation
Issue number1
StatePublished - Feb 2007

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering


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