We define here a new symmetry operator called reciprocation. Apertures that remain unchanged afler reciprocation are called self-reciprocal, and have a number of unique properties. When excited suddenly by a voltage, a self-reciprocal aperture becomes an antenna. This antenna is an approximation to a TEM horn, to a lens IRA (TEM feed + lens), or to a reflector IRA (TEM feed + reflector). Becaus...

In recent works the authors have shown that it is possible to retrieve the full velocity vector of a moving target from Synthetic Aperture Radar (SAR) data using a single sensor. This paper addresses the design of the radiation antenna pattern leading to the best velocity estimates. Aiming at this goal, the Fisher information matrix for the unknown moving targets velocity parameters is computed...

Different fractal antennas based on aperture coupled feeding technique are studied, analysed and compared for size reduction, low profile, and good omini‐dirctional pattern suitable for RFID applications. The results are used as a guideline to propose modified fractal shapes patch antennas having lower size reduction parameters. All the designed antennas are bas...

Nomenclature A Aperture area of the antenna (square meters) D Diameter of antenna aperture (meters) Ef Gravitational potential energy due to film (Joules) Ep Hydrostatic pressure potential energy (Joules) ET Total energy of the inflatable reflector system (Joules) F Focal length of antenna (meters) G Effective antenna gain GI Ideal antenna gain g Acceleration due to gravity (meters per square s...

Some new focusing properties of time-domain ultra wide band (UWB) focusing array antennas are presented. The large current radiator (LCR) is considered as the UWB antenna element. Each LCR is replaced by a set of infinitesimal dipoles modeling both the near field and the far field patterns of the antenna element, as well as the coupling between the elements. Several antenna arrays with differen...

This paper proposes a patch antenna array as an alternative feed for dish antennas on board satellites to solve the weight problem constituted by conventional feed horns. An 8x1 linear, C-Band, circular patch antenna array configuration with a broadside radiation pattern is designed as feed for a dish antenna with F/D ratio of 0.36 corresponding to aperture illumination of 140. The result of an...

An isolation enhanced dual polarized microstrip patch antenna has been designed for Sband Synthetic Aperture Radar. This antenna operates at 3.125 GHz with operating bandwidth of 150 MHz or 4.8%. The electromagnetic power is coupled from the feed line to radiating patch through proximity coupling feeding technique for better bandwidth achievement. A centre groundshorted microstrip line is creat...

The future National Polar-orbiting Environmental Satellite System (NPOESS) Microwave Imager/Sounder (MIS), a space-borne conical scanning radiometer, uses an offset main reflector with multiple antenna feedhorns to receive upwelling microwave radiation from the Earth’s surface and atmosphere. The offset reflector approach is a convenient and economic way to achieve the desired antenna footprint...

Antenna efficiency is one of the most important figures merit a radio telescope for observations, especially at millimeter wavelengths or shorter wavelengths, even multibeam telescope. To analyze system with beam waveguide, lossless antenna consisting two apertures in series considered frame scalar wave approximation. We found that can be evaluated field distribution over second aperture, and f...

The design and analysis of an ultra wideband aperture antenna with dual-band-notched characteristics are presented. The proposed antenna consists of a circular ring exciting stub on the front side and a circular slot on the back ground plane. By utilizing a parasitic strip and a T-shaped stub on the antenna structure, two notched bands of 850 MHz (3.5-4.35 GHz) and 900 MHz (5.05-5.95 GHz) are a...