Document Type


Date of Award

Summer 8-31-2009

Degree Name

Master of Science in Electrical Engineering - (M.S.)


Electrical and Computer Engineering

First Advisor

Edip Niver

Second Advisor

Gerald Martin Whitman

Third Advisor

Ali N. Akansu

Fourth Advisor

William N. Carr


In this thesis, novel designs of radio-frequency identification (RFID) tag antennas with better matching characteristics to achieve extended range for passive tags have been investigated in the ultra-high frequency (UHF) band. A variety of cavitybacked/coupled microstrip dipole antennas in 915 MHz range were considered. Additionally, a negative impedance converter designed to cancel out antenna's input capacitance at resonance frequency and to produce the real antenna input impedance was designed, simulated and implemented for an RFID antenna. Numerical simulations have been carried out using ORCAD software package (Cadence), ADS software package (Agilent) and HFSS software package (ANSYS/ANSOFT Inc). Antennas have been designed, fabricated and tested; and a comparison of simulated and measured results were done. Further work is recommended to tune antennas to lower the return loss at operating frequency, in order to achieve an optimized range for use with passive tags.