Energy Harvesting of Ambient E.M Waves by Employing Different Types of R.F. Antenna

Used to operate small electronic devices, such as the cell phones. This work will deal with the electromagnetic signals as a renewable energy sources. An analog circuit will prepare using diodes and a charged capacitance and antenna to convert the energy of ambient E.M. waves (Radio Frequencies RF) to a D.C. voltage. The measurements will be demonstrated using different kinds of antenna. In addition, the ambient RF frequency according to Iraq/Babylon/Hilla city will be collected from the communications tower and measured using a receiver circuit.in this paper used three kinds of antenna, wire antenna, air antenna, dish antenna, Measuring the DC Power. the amount of the DC Power that obtained using a dish antenna is approximate the energy that collected using an air antenna. The amount of the DC. Power could be controlled by the charging time (RC) of the capacities.

Design of a Crooked-Wire Antenna by Differential Evolution and 3D Printing

Antenna design often requires dealing with multiple constraints in the requirements, and the designs can be modeled as constrained optimization problems (COPs). However, the constraints are usually very strange, and then the feasible solutions are hard to be found. At the same time, the robustness for antenna design is an important consideration as well. To solve the above issues, the combination of differential evolution algorithm (DE) and 3D-printing technique is presented to design a new crooked-wire antenna. In the design process, DE is adopted to handle the constraints since DE is simple and efficient in finding feasible solutions. The objective of the modeled COP, which is the sum of variance of the gain, axial ratio, and VSWR over the frequency band, is used to enhance the robustness of the antenna and widen the frequency band without additional computational cost. The precision of fabricating the antenna is ensured by using 3D-printing. The design of the NASA LADEE satellite antenna is chosen as an example to verify the method of this paper.

Directivity enhancement of a cylindrical wire antenna by a graded index dielectric shell designed using strictly conformal transformation optics

A transformation-optical method is presented to enhance the directivity of a cylindrical wire antenna by using an all-dielectric graded index medium. The strictly conformal mapping between two doubly connected virtual and physical domains is established numerically. Multiple directive beams are produced, providing directive emission. The state-of-the-art optical path rescaling method is employed to mitigate the superluminal regions. The resulting transformation medium is all-dielectric and nondispersive, which can provide broadband functionality and facilitate the realization of the device using available fabrication technologies. The realization of the device is demonstrated by dielectric perforation based on the effective medium theory. The device’s functionality is verified by carrying out both ray-tracing and full-wave simulations using finite-element-based software COMSOL Multiphysics.

ABOUT THE FEATURES OF CALCULATING THE NEAR ELECTRIC FIELD ESTABLISHED BY THE TRANSMITTING VLF, LF TRAILING WIRE ANTENNA ON THE ENGINE POD OF TUG AIRCRAFT

The near electric field established by the transmitting VLF, LF trailing wire antenna on the engine pod of the tug aircraft is calculated by the Pocklington’s integral equation method. Here are considered the features of solving the problem related to the small electric lengths of the aircraft and pod.

Closed-Form Expressions for Numerical Evaluation of Self-Impedance Terms Involved on Wire Antenna Analysis by the Method of Moments

This paper proposes new closed expressions of self-impedance using the Method of Moments with the Point Matching Procedure and piecewise constant and linear basis functions in different configurations, which allow saving computing time for the solution of wire antennas with complex geometries. The new expressions have complexity O(1) with well-defined theoretical bound errors. They were compared with an adaptive numerical integration. We obtain an accuracy between 7 and 16 digits depending on the chosen basis function and segmentation used. Besides, the computing time involved in the calculation of the self-impedance terms was evaluated and compared with the time required by the adaptative quadrature integration solution of the same problem. Expressions have a run-time bounded between 50 and 200 times faster than an adaptive numerical integration assuming full computation of all constant of the expressions.

Design and Development of a Near Isotropic Printed Arc Antenna for Direction of Arrival (DoA) Applications

This research presents an easy to fabricate isotropic printed arc antenna element to be used for direction of arrival (DoA) arrays. The proposed antenna exhibits a total gain variation of 0.5 dB over the entire sphere for 40 MHz impedance bandwidth at 1 GHz, which is the best design isotropy reported in literature so far. In addition, the isotropic bandwidth of the antenna for total gain variation of ≤3 dB is 225 MHz with 86% efficiency. The isotropic wire antenna is first designed and simulated in Numerical Electromagnetic code (NEC). An equivalent printed antenna is then simulated in CST, where single (short circuited) stub is integrated with the antenna for input matching and the results of NEC simulations are verified. The planar antenna is then manufactured using FR4 substrate for measurements. Good agreement between the measured and simulated results is observed, however the total gain variation is increased to 2 dB for the fabricated antenna. This is because of the unavoidable field scattering from the antenna substrate, the feed cables, and the antenna testing platform.