Spherical near field antenna measurements

Download

index.pdf

Date

2019

Author

Kılıç, Hüsnü Doğan

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

257
views

167
downloads

Accurate determination of the antenna characteristics is one of the key subjects where different methods have been developed for this purpose. When advantages and facilities of these methods are considered, near field measurements have come forward especially in recent years. In this thesis, one of these methods which is referred to as spherical near field measurement method, has been studied. First, wave expansion in the spherical coordinates is introduced. This enables expressing the field as summation of modes which are composed of vector wave functions and coefficients of these functions. It is shown that by obtaining coefficients for measurement distance, field can be obtained at any other distance with these coefficients. However, test setup of an antenna is composed of receiver and transmitter such that one of them is antenna under test and other is measurement antenna which is usually called the probe. Hence, probe effects on the measurement must also be included for accurate results. Initially, Lorentz’s Reciprocity Theorem had been used for this purpose. Then scattering matrix theory has been more commonly used. In this thesis study, scattering matrix theory is explained and generation of transmission formula with the probe compensation is presented. Different numerical integration techniques are used in order to calculate wave coefficients and comparisons are given. Eventually, tests with the theoretical data and results of measured antennas are performed and results are discussed.

Subject Keywords

Antennas (Electronics)., Keywords: Near Field to Far Field Transformation, Spherical Wave Expansion, Scattering Matrix Theory of Antenna, Transmission Formula, Numerical Integration.

URI

http://etd.lib.metu.edu.tr/upload/12624392/index.pdf
https://hdl.handle.net/11511/44170

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Design of Irregularly Shaped Patch Antennas by using the Multiport Network Model Sener, Goker; Alatan, Lale; Kuzuoğlu, Mustafa (2008-07-11) The multiport network model (MNM) is an analytical method that is used to analyze microstrip antennas. MNM is based on defining ports along the periphery of the patch and evaluating the impedance matrix corresponding to these ports by using the Greenpsilas function for the cavity under the patch. For regular rectangular, triangular and circular patches, analytical expressions for the Greenpsilas function are available. In the analysis of irregular patches, Greenpsilas functions cannot be calculated explicit...
Development of PDMS-based micromachining process for microfluidic reconfigurable antennas / Seyedpour Esmaeilzad, SeyedehNasim; Külah, Haluk; Topallı, Kağan; Department of Electrical and Electronics Engineering (2015) The objective of this thesis is to develop fabrication methods to implement microfluidic-based reconfigurable antennas. As the initial structure, a microfluidic based reconfigurable antenna is developed for transmitarrays, which consists of a multi-layered structure incorporating a microfluidic channel to confine liquid metal. The microfluidic channels are fabricated using soft lithography techniques where the channel material is PDMS. PDMS-to-glass and PDMS-to-PDMS bonding processes are optimized to achiev...
Analysis of spherical-rectangular printed antennas and antenna arrays using cavity model Demir, Oğuz; Dural Ünver, Mevlüde Gülbin; Department of Electrical and Electronics Engineering (2017) Printed antennas are commonly used since these antennas are preferred in many applications due to their advantageous properties. In order to employ these antennas in such applications, a thorough investigation and analysis are generally required. Although this can be implemented with fully numerical methods for the sake of high accuracy, the complex calculations required in the process lead to heavy computational load, hence generally demands high quality simulation software. In this thesis, the spherical-r...
Modified neural multiple source tracking algorithm in the presence of mutual coupling Caylar, Selcuk; Leblebicioğlu, Mehmet Kemal; Dural, Guelbin (2007-06-15) In smart antenna systems, mutual coupling between elements can significantly degrade the processing algorithms [1]. In this paper mutual coupling effects on Modified Neural Multiple Source Tracking Algorithm (MN-MUST) has been studied. MN-MUST algorithm applied to the Uniform Circular Array (UCA) geometry for the first time. The validity of MN-MUST algorithm in the presence of mutual coupling has been proved for both Uniform Linear Array (ULA) and UCA. Simulation results of MN-MUST algorithm are provided fo...
Reconfigurable CPW-FED dual-frequency rectangular slot antenna using RF MEMS technology Erdil, Emre; Topalli, Kagan; Aydın Çivi, Hatice Özlem; Akın, Tayfun (2005-07-08) A reconfigurable dual-frequency rectangular slot antenna using MEMS technology is presented. In this structure, a rectangular slot antenna is integrated with MEMS cantilever type capacitors. Simulation results show that the structure has a dual frequency behavior where both of the resonant frequencies can be reconfigured dynamically. By the actuation of MEMS cantilevers, the lower resonant frequency shifts 1.2 GHz, whereas the higher resonant frequency has a shift of 330 MHz without any distortion of the ra...

Citation Formats

H. D. Kılıç, “Spherical near field antenna measurements,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Electrical and Electronics Engineering., Middle East Technical University, 2019.