Farhad Farzami

Pattern Reconfigurable Antenna


A printed dipole antenna is designed with two parasitic elements loaded by embedded resonators to provide reconllgurable patterns.

Thin Magneto-dielectric Substrate for Antenna Miniaturizing

Miniaturization of a rectangular microstrip antenna using a magneto-dielectric substrate is discussed theoretically and experimentally.

Pattern Reconfigurable Printed Dipole Antenna Using Loaded Parasitic Elements
A printed dipole antenna is designed with  two parasitic elements loaded by embedded resonators to provide reconfigurable patterns. The embedded resonators in the parasitic elements are loaded by varactor diodes, which change the phase and the transmission coefficient responses of the parasitic elements. This allows the parasitic elements to act as either a director, a reflector or a neutral element. The proposed printed dipole antenna with two loaded parasitic elements acts as a printed Yagi-Uda antenna.  Because the parasitic elements can act as either a director or a reflector, the directed gain can be increased and  the Front to Back Ratio (FBR) may be improved up to  42~dB. It is also possible to achieve different target FBR if broadcasting is needed in two directions of the boresight. This pattern reshaping can be obtained as quickly as the diodes can change their capacitance. The antenna is designed to operate at 2.4~GHz, but this design approach can be applied to other  frequency bands. The simulation  and measurement results are in  good agreement.
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Microstrip Antenna Miniaturization by Using a Novel Magneto-dielectric Substrate
Miniaturization of a rectangular microstrip antenna using a magneto-dielectric substrate is discussed theoretically and experimentally. A compact magneto-dielectric substrate is designed using a metamaterial structure which can reduce the antenna dimensions by increasing the constitutive parameters of the substrate. Furthermore, the proposed structure is thin enough to be embedded in a single dielectric substrate. The area of the microstrip antenna with the proposed magneto-dielectric substrate at 2.4GHz is reduced up to about 65% compared to a conventional dielectric microstrip antenna. The bandwidth of the miniaturized antenna is almost unchanged due to the increase of the magnetic permeability at the designed 2.4 GHz frequency. Finally a fabricated version of the miniaturized antenna is tested and measured. The results of the meaurement and simulation are in good agreement.
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