Design and realization of high power low loss combiners

Suna, Gonca
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 GHz frequency ranges are investigated and implemented. It is shown that planar probe coaxial waveguide combiner has much lower loss compared to the other ones. Therefore, 8 identical 2 W power amplifiers are combined using planar probe coaxial waveguide combiners of two different operating frequency bands to get 15 W outputs in both 8-12 and 15-18 GHz frequency ranges successfully.


Countermeasure methods for high power microwave pulses /
Keskin, Muharrem; Demir, Şimşek; Department of Electrical and Electronics Engineering (2014)
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 limit...
Design and Performance Analysis of a Grid Connected PWM-VSI System
Kantar, Emre; Usluer, S. Nadir; Hava, Ahmet Masum (2013-11-30)
Pulse-width modulation (PWM) voltage source inverters (VSIs) are favorable interface devices to the power grid for renewable energy systems. This paper deals with the design of the LCL-filter and inverter for the grid-connected VSI. A complete design procedure for both reactive and passive components of LCL-filter is demonstrated with a new iterative approach in selection of the filter inductors. The design process for a two-level VSI is clearly illustrated through an example and the dynamic response is inv...
Development andcharacterization of activated carbon / transition metal phosphide composites for electrochemical capacitors
Köse, Kadir Özgün; Aydınol, Mehmet Kadri (null; 2019-09-11)
Electrochemical capacitors are the energy storage devices based mainly on electrical double layer formation. Their power densities are exceptionally high; however, their energy densities are characteristically low to compete various types of batteries in market. Therefore, there have been great amount of studies to enhance electrochemical capacitors’ energy density. Utilization of inorganic materials such as transition metal oxides and/or phosphides is one of the most common strategies to increase energy de...
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...
Design and Analysis of PLLs for Line-connected Converters in Three Phase Systems
Vyawahare, D.; Kose, H.; AYDEMİR, MEHMET TİMUR; Chandorkar, M. C. (2011-09-10)
This paper is concerned with phase locked loop (PLL) structures for use in the control of line connected power electronic converters in three phase systems. Such converters have to operate under conditions in which the power system phase voltages are often unbalanced. The unbalanced and distorted line voltage vector as observed in the stationary reference frame generally has instantaneous rates of change components in the radial as well as in the angular directions. The essential task of a PLL in this conte...
Citation Formats
G. Suna, “Design and realization of high power low loss combiners,” M.S. - Master of Science, Middle East Technical University, 2013.