الفهرس 
CHAPTER 1: IntroductionOnly 14 pages are availabe for public view
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Abstract
This thesis addresses the analysis and design of reconfigurable sensing antennas (RSAs).
RSA is an antenna which is not only transmit and receive electromagnetic waves, but also
can sense the ambient environments. The radiation characteristics of a RSA are
reconfigured by a physical sensor unit whose properties depend on the environment.
Several antennas have been designed to monitor the humidity level, gas concentration,
movement, and temperature.
In this thesis, RSAs are designed to monitor variations such as angular displacement sensor,
temperature sensing in radio frequency (RF) ranges and in THz ranges and gas sensing.
The radiation properties of the reconfigurable antennas are investigated and analyzed using
a finite integral technique (FIT) and finite element method (FEM). A planar circular split
ring resonator (CSRR) coupled to microstrip transmission line (TL) for the rotation angle
sensor is introduced. For each rotation angle, the CSRR acts as a stop-band filter and
absorbs the signal flow through the TL. The CSRR sensor introduces a resonance at 4.13
GHz with a -10 dB bandwidth of 370 MHz. High attenuation of 40 dB is achieved with
reflection of 0.17 dB. A parametric study on the effect of each of CSRR design parameters
on the performance of the sensor is introduced. The performance of the proposed sensor
for rotation angle detection is investigated. A five-elements equivalent circuit model is
prepared to represent the inductive and capacitive coupling of the CSRR and TL. The
particle swarm optimization (PSO) technique is employed to find the optimal values of the
equivalent circuit elements at different rotation angles.
The multiresonator circuit is used for encoding data by the chipless tag as cascaded
curl resonators with changing its length placed close to a microstrip line. The chipless RFID
tag, operates in 3-7GHz band is proposed. The transmission coefficient, magnitude and
phase, is used to indicate the coded signal. Integration of circular ultra wide band (UWB)
microstrip monopoles and curl resonators to form a chipless tag are presented. The
encoding of data is changed by inserting a cut in order to shift the curl resonant frequencyAbstract
outside the band of interest. Temperature sensor chipless RFID tag is proposed for dual
performance of tagging and sensing temperature simultaneously.
A microstrip patch antenna based on the indium antimonide (InSb) semiconductor
material for temperature sensing applications is introduced. The proposed sensing antenna
is designed and optimized to operate in the THz band. The electrical properties (complex
relative permittivity) of the InSb-material is investigated at different temperatures. The
proposed sensing antenna introduces high temperature sensing sensitivity of 1.588 GHz/K.
The impedance matching bandwidth is 9.57% with maximum gain of 6.4 dBi at 300 K.
Broadside temperature insensitive radiation pattern is obtained. The proposed sensor is
designed for temperature sensing range from 250 K to 400K. The antenna resonant
frequency can be controlled via changing the temperature of the surrounding medium with
wide tuning range from 264 GHz to 502.2 GHz. The proposed sensor has a wideband
frequency tuning range of 90.2 %. The radiation efficiency is increased from 2.5% at T=250
K to 86.3% at T=400 K. An equivalent circuit of five lumped elements for the sensing
antenna is estimated using particle swarm optimization technique at different temperatures.
A polarization independent gas sensor using crescent plasmonic dipole antenna
loaded with graphene monolayer for environment monitoring is proposed. Single, dual,
and four arms crescent dipoles are designed and investigated. The proposed gas sensor has
reconfigurable absorption characteristics in the wavelength range from 900 nm to 1600 nm.
A parametric study on the effect of the sensor dimensions and polarization of the
illuminated waves on the total absorption of different gases is investigated. A graphene
monolayer is used to enhance the gas molecule absorption in its unbiased state. An
enhancement of the total absorption cross-section (ACS) values for n=1.4 is 1.028×105 nm2
for unloaded sensor, and is 1.77×105 for the graphene loaded case. The unloaded graphene
sensor sensitivity is 630 nm/RIU, and for the graphene loaded case is 677.5 nm/RIU. Dualpolarized crescent dipole consists of two orthogonal arms is designed to give the same
sensitivity for x- and y-polarized E-field illumination. A polarization independent gas
sensor consists of four crescents dipole arms rotated with 45o is explained. An enhancement
of gas absorption is achieved by using a sensor array of four-arms dipole sensor. DifferentAbstract
array sizes loaded with graphene monolayer are investigated. The total ACS peak value is
7.84×106nm2 for 6×6 dipole array.