Hala Elsadek

Antenna Designs with Electromagnetic Band Gap Structures

The word “meta”, in Greek language, means beyond. It implies that the electromagnetic response of metamaterials (MTMs) is unachievable or unavailable in conventional materials. Many efforts have been done to search for an adequate definition for MTMs. In 2002, J.B. Pendry wrote in a conference paper: “meta-materials, materials whose permeability and permittivity derive from their structure”. Later, in 2006, C. Caloz and T. Itoh wrote: “Electromagnetic metamaterials are broadly defined as artificial effectively homogeneous electromagnetic structures with unusual properties not readily available in nature” [1]. Perhaps, a serious obstacle on the road to a universal definition for the term MTMs is the fact that researchers working with these objects do not commonly agree on their most essential characteristics. In [2] and [3], some of the problematic aspects of the non-naturality definition were raised, like the difficulty in separating classical composites from the new class of metamaterials. Another argument against the “not found in nature” property is that it unnecessary excludes impressive examples of natural media that could be called metamaterials par excellence, such as structural colors [4].

Design of compact DRH antenna For GPR transmitter application

A compact double-ridged horn antenna (DRH) for the transmitter of ground penetrating radar applications in the frequency range of 80MHz to 1GHz. Within this contribution the design and simulation of such an antenna will be considered for water level detection in Egyptian dessert aquifers (depth ≥ 10m). Among the varying horn design parameters, the linear and exponentially tapered walls are studied as well as variations of the curvature of the dielectric waveguide between the two ridges enhancing matching hence reducing size and increasing operational bandwidth. The design goal is a broad bandwidth antenna with maintaining compact dimensions. Two modifications have been introduced on the conventional triangular. first multifunction tapering of the horn plates with curvature ending, second inserting protruding two ridges between the aperture planes and filling the space between the ridges with high constant dielectric material, in order to lower the operating frequency without increasing the size of the original setup. The proposed design has been applied to subsurface radar applications. The antenna 80 × 70 × 117cm resembles improvement in size as compared with some commercial GPR horn antennas as Satimo Horn model SH 68 (operating range 68-1020MHz with dimensions 2.98×1.61×2.5m). Simulations are done using CST Microwave Studio.

A compact 3D-microwave holographic pointer system using a size reduced microstrip planar array

A compact system for a three dimensional (3D) pointer (mouse) is possible by combining microwave holography with microstrip antenna arrays to enter 3D coordinates of a point in space into computer memory. To reach the practical reduced size system, new solutions are proposed in both the receiving planar array antenna for constructing the point hologram image and the holographic algorithms for reconstructing the microwave hologram.

Size reduced microstrip planar antenna array for a compact 3D-mouse microwave holographic system

A compact system for establishing a three dimensional (3D) mouse or pointer is possible by combining microwave holography with microstrip antenna arrays to enter 3D coordinates of a point in space into computer memory. To get the reduction on the system size, new solutions are proposed in both the holographic algorithms and the receiving planar array antenna.