Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 8 of 8 for “"helical antennas"”.
-
Multifilar Hemispherical Helical Antennas
Helices are broadband antennas that provide moderate gain, largely real input impedance and circular polarization when operating in the axial mode regime. A modified form of the helix, the spherical helix, has been shown to yield similar polarization and gain characteristics over a narrow bandwidth …
-
Helical Antennas with Truncated Spherical Geometry
A new variation of the spherical helical antenna made of a wire wound over a hemispherical surface and backed by a conducting ground plane is introduced. A constant spacing is maintained between the turns of winding. The geometry of this antenna is fully described by the number of turns and the …
-
New Designs for Wideband Hemispherical Helical Antennas
A unique property of spherical and hemispherical helical antennas is that they provide very broad half-power beamwdiths and circular polarization over a narrow bandwidth. In this thesis, new designs for hemispherical helical antennas are introduced that provide significant improvement in bandwidth, …
-
Numerical Analysis of Helical and Log-periodic Antennas for Short Pulse Applications
The planar log-periodic (LP) and helical antennas are numerically studied as two antennas with a wide range of applications. The advantages of the LP antenna are the large adjustable bandwidth as a frequency independence radiator, its low profile, and that it can be made to be elliptically …
-
Helical Antenna Optimization Using Genetic Algorithms
The genetic algorithm (GA) is used to design helical antennas that provide a significantly larger bandwidth than conventional helices with the same size. Over the bandwidth of operation, the GA-optimized helix offers considerably smaller axial-ratio and slightly higher gain than the conventional …
-
Low-power dual-band on-body antenna for wireless body sensor networks
… as a central antenna for WBAN. Five types of helical antennas are proposed in the present thesishaving a dual-frequency operation at 2.45 GHz and 5.8 GHz. The proposed antennas are optimized to maximize the Signal-to-Noise-Ratio (SNR) and, hence, to minimize the BER and the Specific Absorption …
-
Modelling and analysis of complex electromagnetic problems using FDTD subgridding in hybrid computational methods. Development of hybridised Method of Moments, Finite-Difference Time-Domain method and subgridded Finite-Difference Time-Domain method for precise computation of electromagnetic interaction with arbitrarily complex geometries
… parallel wires, such as dipoles, loops and helical antennas are computed. The results are found to be stable and showed good agreement with less comprehensive earlier work by others. The work also investigated the interaction between overhead high voltage transmission lines and underground …