الفهرس 
CHAPTER 1: IntroductionOnly 14 pages are availabe for public view
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Abstract
This thesis introduces the analysis and design of water liquid antennas (WLA) for
wireless communication systems. WLA is an antenna which use water to transmit and receive electromagnetic waves. Water based antennas have many advantages
compared with traditional liquid antennas such as low cost, safety material, ecofriendly and reconfigurable material. Other liquids like mercury is atoxic material and eutectic gallium indium (EGAIN) is expensive material. There are many parameters affect the water antennas performance like frequency, temperature and salinity. In this thesis, WLAs are employed in several applications such as wearable application WIFI, MIMO, and LTE applications in radio frequency (RF) ranges. The electrical properties of the water are investigated at different temperatures. The
radiation properties of the reconfigurable water antennas are investigated and analyzed using a finite integral technique (FIT) and finite element method (FEM). A
cubic DRA water antenna with strip feeding at a 2.4 GHz is introduced. A partial ground plane is used to increase the bandwidth and is compared with the full ground
plane. A parametric study on the effect of different feeding mechanism on the performance of the antenna is investigated. A water microstrip antenna (WMA) with polarization reconfigurable states is explained. The antenna has low profile, flexible and low cost structure. The water is held by a container from a dielectric material and the antenna is fed by an L-shaped probe. The radiation characteristics of a single element WMA with circularly polarized radiation for WiMax and RFID systems at 2.45 GHz are investigated. The WMA has a high radiation efficiency of 95% with 28.6 % matching bandwidth. The effect of varying the environmental temperature on the performance of the WMA is introduced. To realize the polarization reconfigurability, two adjacent containers are designed with a single feeding. Therefore, the polarization of the proposed antenna is switched between three
Abstract
different states, according to the water injection or extraction from containers. When a single container is filled with water and the other is empty the radiated field will have right-hand or left-hand circular polarization. When both containers are filled with water a linearly-polarized (LP) wave is radiated. Consequently, the reconfigurable polarization is obtained by controlling the water flow, where a wide circular polarization bandwidth of 29.5 % is obtained. The water patch antenna is applied in MIMO systems and 5G applications. High efficiency salty water based reflectarray antenna for maritime wireless communications at 740 MHz is introduced. The proposed reflectarray consists of 169 unit-cell elements with area of 330.2 × 330.2 cm2. Each unit-cell element consists of a cylindrical dielectric container filled with salty water and is mounted on a conducting plate. It introduces a reflection phase variation from 0 to 313 .ْ The reflectarray is designed and analyzed using the finite integral technique and compared with that calculated using the finite element method. The radiation characteristics of 13 × 13 salty water based reflectarray are investigated and presented. The main beam direction of the salty water based reflectarray is controlled by the water level in each unit-cell element through an electronic valves. The reflectarray introduces a maximum gain of 26.2 dB at 740 MHz and 1-dB gain bandwidth of 50 MHz. The effect of temperature variation on the radiation characteristics of the water-based reflectarray is investigated. A polarization reconfigurable DRA based on liquid flow control is presented. The DRA consists of a rectangular dielectric material with two pairs of unsymmetrical rectangular holes drilled on the dielectric DRA. By alternating liquid injection and extraction in the two pairs of holes, different cases of polarization are produced. A parametric study on the effect of two pairs of holes are investigated for optimum CP radiation. Left-hand, right hand circular polarization and linear polarization are obtained.