Design of high power waveguide limiter /

Download
2014
Yılmaz, Abdullah
Microwave limiters are protector structures. Microwave limiters protect the receiver circuits from high power microwave signals. Receiver circuits of radar systems are able to process the signals with low level amplitude. This situation results in usage of very sensitive circuit blocks. These sensitive circuit blocks, such as LNAs, are protected from high power signals by limiters. The causes of the undesired microwave signals with high level amplitude can be transmitter to receiver leakage and high power microwave short pulses coming from outside as an enemy attack. Transmitter leakages are predictable threats because transmitted signal timing is known. However threats from outside is unpredictable because the time of threat cannot be known. Outside threats can cause problem in the radar system at any time. In order to protect receiver channel of radar system, low response time high power microwave limiter must be used. In this study, two critical points are aimed. The limiter, which can handle the signals with kW power levels, and which have low response time is aimed. Two different single stage waveguide limiters, whose operating frequency bands are 9.4-10 GHz, are designed with two different high power pin diodes. Linear/Nonlinear measurements of waveguide limiters are performed. Then these two single stage limiters are connected in cascade and the resulting two stage waveguide limiter is measured. In order to increase the sensitivity and the response speed of the waveguide limiter, the waveguide detector is designed with the Schottky diode. The limiters are measured with the WG detector. Circuit designs and simulations are performed using AWR® and CST®.

Suggestions

Design and realization of high power low loss combiners
Suna, Gonca; Yıldırım, Nevzat; Department of Electrical and Electronics Engineering (2013)
In recent high power microwave systems, power generation is commonly achieved by combining a bunch of transistor amplifier. Regarding the efficiency of power combining operation, insertion loss of the combiner is a critical parameter. In this thesis, several low loss power combiners, namely, microstrip Wilkinson combiner in 6-18 GHz frequency range, suspended stripline branchline couplers in 16.5-17.5 GHz frequency range and finally, planar probe coaxial waveguide combiners in 8.5- 11.5 GHz and 15.5-17.5 GH...
Modelling and Precalculation of Additional Losses of Inverter Fed Asynchronous Induction Machines for Traction Applications
Muellner, F.; Neudorfer, H.; Schmidt, E. (2011-09-10)
The inverter supply of asynchronous induction machines for traction applications has a major influence on both electromagnetic and thermal performance. In addition asynchronous induction machines used with traction drives of rail transportation vehicles have different design strategies compared against commonly used standard machines. Generally, the design of these machines requires high electromagnetic and thermal stress. Thus, the additional losses caused by the inverter have to be considered with the ini...
DEVELOPMENT OF POLYMER MATRIX COMPOSITES WITH TUNABLE DIELECTRIC PROPERTIES
Özkaragöz, Nadire Nazlı; Dericioğlu, Arcan Fehmi; Department of Metallurgical and Materials Engineering (2022-2-08)
Ferroelectric materials are used in different applications because of their superior electrical and dielectric properties. Ferroelectric materials are polarized when an electrical field is applied to the material. This spontaneous polarization continues even if an electrical field is removed. BST (Barium Strontium Titanate) is one of the attractive ferroelectric materials which has a high dielectric constant and low dielectric loss tangent (tanδ). High dielectric constant and low loss tangent are necessary ...
Design and realization of a broad band antenna loaded with a metamaterial-inspired lens for subsurface microwave imaging applications
Yeşilyurt, Ömer; Sayan, Gönül; Department of Electrical and Electronics Engineering (2019)
Ultra-wideband antennas are critical sensors for microwave imaging. In this work, radiation performance of an antipodal Vivaldi antenna is enhanced by using a broadband metasurface lens structure in 1-6 GHz bandwidth. Radiation pattern for the lens integrated antenna is more directive due to electromagnetic properties of the metasurface lens. In order to create such a lens, electrically responsive metamaterial unit cells with high effective permittivity values are designed. As we want to obtain a broadband ...
Controlling light inside a multi-mode fiber by wavefront shaping
Binici, Halil İbrahim; Yüce, Emre; Kocaman, Serdar; Department of Micro and Nanotechnology (2018)
Light is the primary tool used for collecting information from macroscopic and microscopic structures of matter. Micro-nano technology based materials like microcavities, waveguides, photonic crystals and fibers are used for confining light in space and the latter enable long distance information transfer. To increase the capacity of an information link, the core size of an optical fiber must be increased. Due to increased size of the fiber, the number of supported modes increases and becomes a multi-mode f...
Citation Formats
A. Yılmaz, “Design of high power waveguide limiter /,” M.S. - Master of Science, Middle East Technical University, 2014.