F. Ayoub

A MIMO cognitive radio antenna system

This paper presents an antenna system dedicated for cognitive radio applications. The proposed antenna system consists of two sets of radiating structures. The first set is a two port frequency reconfigurable antenna and the second set is a two port sensing antenna. A prototype antenna is simulated, built and tested to prove the validity of a MIMO system for cognitive radio applications. A good agreement is found between the simulated and the measured data.

3D printed miniaturized quadrifilar helix antenna

This paper presents the design of a 3D printed quadrifilar helix antenna. The antenna is miniaturized by loading the tip of each helix by metallic circles of equal dimensions. The effect of decreasing the resonant frequency is also achieved by introducing a dielectric material within the antennas physical structure. A prototype is fabricated and tested to prove the proposed technique. A good agreement is obtained between the theoretical and measured results.

Liquid crystal reconfigurable circularly polarized patch antenna

Traditional patch antennas are light-weight and easy to manufacture, but suffer from narrow operational bandwidth. The topic considered here is the design and development of a reconfigurable right handed circular polarized patch antenna at the X-band. Reconfigurability of the studied antenna stems from the highly anisotropic dielectric properties of nematic liquid crystals (LC). Both, simulated and experimental data are presented and discussed.

A frequency/pattern reconfigurable modified dipole antenna array

This paper presents a reconfigurable antenna array that is made of four printed dipole elements. The change in the array operating frequency is achieved by feeding separately each array element via an external reconfigurable feeding network. The pattern diversity is achieved by incorporating a printed reflector between the array elements. A prototype antenna is fabricated and tested.

Frequency-tunable patch array using highly anisotropic liquid crystal

A liquid crystal (LC) based microstrip patch antenna array with frequency tuning capabilities operating in the X-band is presented. Frequency tunable capabilities of the presented antenna array are shown to come from the dielectric anisotropy of liquid crystals at microwave frequencies. This array is fed by a single microstrip line, with individual control of each array element. The design thus offers total array tunability from a single unaltered RF source.

Preliminary rain attenuation studies for W/V-band wave propagation experiment

The need to investigate higher frequencies for satellite communication led to the W/V-band Terrestrial Link Experiment (WTLE) project. This project is assessing atmospheric propagation effects at W/V-band frequencies, particularly rain-fade. In this paper, two rain attenuation models (i.e., the ITU-R and the Silva-Mello model) are compared to experimental measurements. The step-by-step comparison, along with all the tools used, is described herein.

Reconfigurable cyclical patch antenna

The design of a reconfigurable cyclical printed antenna is discussed in this paper. The antennas topology allows a wide bandwidth of operation and an ability for radiation pattern reconfiguration.. The antenna is designed at Ka-band, with different modes of radiation pattern characteristics. The different operational states reshape the radiation beam and redirect major radiation pattern lobes towards desired directions. The antenna is proposed for radar applications where such reconfigurable characteristic is desired.

The integration of solar cells with PIFA for energy harvesting

This paper presents the idea of achieving a multi-source energy harvesting for improved DC conversion efficiency. Solar cells are integrated with a PIFA that is connected to a wideband rectifying circuit. The wideband rectifying circuit is designed to rectify the RF signals captured by the PIFA. The integrated solar cells with the PIFA are used to extract a DC signal from the solar energy. Prototypes are fabricated and tested as a proof of concept.

Software enabled cognitive radio antenna system

In this paper we discuss an antenna system composed of a reconfigurable communicating antenna and a wideband antenna for sensing purposes. The communicating antenna is a microstrip antenna that is reconfigured by moving its ground plane in a vertical or tilting manner. The sensing antenna is a printed monopole antenna designed for wideband sensing. The whole system is compactly packed and software controlled by an Arduino Uno microcontroller.

2-D cross slotted W-band waveguides array

This paper discusses the design of an 8×16 cross slotted rectangular waveguide array. The array produces a gain of 25 dB at 86 GHz. Great isolation is achieved between the Left Hand Circularly Polarized (LHCP) and Right Hand Circularly Polarized (RHCP) patterns over the entire Half Power Beamwidth (HPBW). Feeding the array at different ports enables both LHCP and RHCP radiation patterns. The array can be proposed for space communication in addition to its ability to be deployed into terrestrial communication systems.