Countermeasure methods for high power microwave pulses /

Keskin, Muharrem
In this thesis, a limiter structure is investigated to decrease the effects of High Power Microwave (HPM) pulses coupled from front-door by using vanadium dioxide (VO2). To prove that vanadium dioxide can be used as an RF limiter, this structure is examined, realized and measured. Firstly, susceptibility of LNA to HPM pulses is investigated by an experimental setup to determine the destruction threshold levels of LNA technology for direct injection of HPM pulses. Based on these threshold levels, diode limiter technology is examined in terms of power handling capacity and response time. The behaviors of two diode limiters against the HPM attacks are studied to have a general idea about diode technology. As a result of this study, for pulses having high amplitudes and short pulse widths, diode technology is not enough to protect the vulnerable front-end devices like LNA’s. Therefore, another limiter structure is needed to handle the HPM pulses. To produce a VO2 limiter, VO2 material is synthesized by using two hydrothermal methods. Then, these produced samples are characterized with X-ray diffraction technique and extraction of resistance characteristics. With this obtained material, a limiter is realized and performance of the limiter is measured and discussed.


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...
Design and development of electromagnetic wave absorbing composites effective at microwave frequencies /
Hamat, Özgür; Dericioğlu, Arcan Fehmi; Department of Metallurgical and Materials Engineering (2014)
In the scope of this study, EM wave absorbing composites effective at microwave frequencies having crucial properties for their structural applicability will be designed and developed making use of a novel approach originating from our research group. For this purpose, surfaces of glass and polymeric fiber woven fabrics were modified via metal coatings with nm order thickness, where EM wave absorbing structural composites were formed by incorporating multilayered combinations of these surface-modified woven...
BULUTAY, C; PRASAD, S (1993-06-01)
Three-dimensional condensed asymmetrical node, variable grid, transmission-line matrix (TLM) method has been used in analyzing several millimeter waveguides on anisotropic substrates. The dispersion characteristics of image guides together with field and energy confinement properties at millimeter-wave frequencies have been investigated. Edge coupled microstrip line on a uniaxial substrate is analyzed for the even and odd mode dispersion characteristics. Finally the same analysis is repeated for bilateral f...
Development of high performance uncooled infrared detector materials
Kebapçı, Başak; Akın, Tayfun; Turan, Raşit; Department of Micro and Nanotechnology (2011)
This thesis reports both the optimizations of the vanadium oxide (VOx) thin film as an active infrared detector material by the magnetron sputtering deposition method and its use during fabrication of proper resistors for the microbolometers. Vanadium oxide is a preferred material for microbolometers, as it provides high TCR value, low noise, and reasonable resistance, and a number of high-tech companies have used this material to obtain state-of-the-art microbolometer arrays. This material is first used in...
Detection of far-infrared radiation using glow discharge detectors
Takan, TAYLAN; ALASGARZADE, Namig; Uzun Kaymak, İlker Ümit; Sahin, Asaf B.; Altan, Hakan (2016-05-01)
The plasma medium, created inside the neon indicator lamp, enables the detection of a wide wavelength range of differential or modulated EM signals. The interaction between the plasma and various frequency EM waves are still being investigated and in the mm-wave/terahertz range the interaction mechanism is still not well understood. In this study commercially available neon indicator lamps are studied using both time-domain and continuous wave mm-wave/THz measurement systems. The glow discharge detector res...
Citation Formats
M. Keskin, “Countermeasure methods for high power microwave pulses /,” M.S. - Master of Science, Middle East Technical University, 2014.