Mert Kalfa

Bilkent University · Department of Electrical & Electronic Engineering

We propose and demonstrate a multiple-precision arithmetic framework applied to the inherent hierarchical tree structure of the multilevel fast multipole algorithm (MLFMA), dubbed the multiple-precision arithmetic MLFMA (MPA-MLFMA) that provides an unconventional but elegant treatment to both the low-frequency breakdown and the efficiency limitatio...

Semantic signal processing and communications are poised to play a central part in developing the next generation of sensor devices and networks. A crucial component of a semantic system is the extraction of semantic signals from the raw input signals, which has become increasingly tractable with the recent advances in machine learning (ML) and art...

Advances in compressed sensing (CS) theory have brought new perspectives to encoding and decoding of signals with sparse representations. The encoding strategies are determined by measurement matrices whose design is a critical aspect of the CS applications. In this study, we propose a novel measurement matrix design methodology for direction of ar...

Semantic signal processing and communications are poised to play a central part in developing the next generation of sensor devices and networks. A crucial component of a semantic system is the extraction of semantic signals from the raw input signals, which has become increasingly tractable with the recent advances in machine learning (ML) and art...

Advances in machine learning technology have enabled real-time extraction of semantic information in signals which can revolutionize signal processing techniques and improve their performance significantly for the next generation of applications. With the objective of a concrete representation and efficient processing of the semantic information, w...

Advances in machine learning technology have enabled real-time extraction of semantic information in signals which can revolutionize signal processing techniques and improve their performance significantly for the next generation of applications. With the objective of a concrete representation and efficient processing of the semantic information, w...

The current state-of-the-art error control of Multilevel Fast Multipole Algorithm (MLFMA) is valid for any given error threshold at any frequency, but it requires a multiple-precision arithmetic framework to be implemented. In this work, we use asymptotic approximations and curve-fitting techniques to derive accurate closed-form expressions for the...

We introduce and demonstrate a new error control scheme for the computation of far-zone interactions in the multilevel fast multipole algorithm (MLFMA) when implemented within a multiple-precision arithmetic (MPA) framework. The proposed scheme provides the optimum truncation numbers as well as the machine precisions given the desired relative erro...

Slotted waveguide array antennas offer low cross-polarization and high power handling capacity, and they are low-profile which enables them to be used in conformal and structurally-integrated antenna solutions. Hence, they are excellent candidates for phased array antennas in radar applications, especially in air platforms. Aerodynamics and radar c...

A method of moments/Green's function (MoM/GF) technique in the space domain is used for the rigorous and fast analysis of cylindrically conformal slotted sectoral waveguide arrays (SSWGAs) in the presence of multilayered cylindrical dielectric radomes. Representing the slots by fictitious magnetic currents via the equivalence principle, the geometr...

An accelerated method for characterizing active reflection coefficients in electrically large uniform active phased arrays is presented. The proposed method only requires the S-parameters related to the center and few edge elements, which dramatically reduces the total number of measurements to be performed with a 2-port vector network analyzer (VN...

form only given. Slotted waveguide antenna arrays with dielectric covers are widely used in both military and civil applications due to their low-profile, high power handling capacity, and the ability to conform to the host platform. Conformity is especially required for air platforms where aerodynamics and radar cross section (RCS) of the vehicle...

form only given. The design and analysis of dielectric-covered slotted waveguide arrays are of great interest in many military and civil applications, because of their low-profile, high efficiency and high power handling capabilities. Regarding the efficient and accurate analysis of such antennas, integral equation (IE) based methods that utilize t...

Closed-form Green's function (CFGF) representations are developed for tangential magnetic current sources to calculate the mutual coupling between apertures on perfectly conducting circular cylinders covered with dielectric layers. The new representations are obtained by first rewriting the corresponding spectral domain Green's function representat...