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ISSN: 1937-6472

Vol. 92

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2021-03-29 PIER B Vol. 92, 47-70, 2021. doi:10.2528/PIERB20122806

Design and Implementation of FPGA-Based FFT Co-Processor Using Verilog Hardware Description Language

Yung-Chong Lee, Yee Kit Chan, and Voon Koo

In this research project, the hardware implementation of a Field-Programmable Gate Array (FPGA) based Fast Fourier Transform (FFT) will be carried out by using Verilog Hardware Description Language (HDL). Since FFT serves as the core for the Range Doppler Algorithm (RDA) in Synthetic Aperture Radar (SAR) processing, it is of paramount importance to evaluate the algorithm and its computational complexity for the design of an efficient FFT hardware architecture. The design process and Verilog hardware description language which is used to describe and model a digital FPGA-based SAR processor will be introduced. Detailed explanation of the hardware implementation for FFT and Inverse Fast Fourier Transform (IFFT) in SAR processing are thus presented. The performance evaluations of the proposed processors including the comparison of the proposed processor with MATLAB-based processor, timing considerations of the processor, and lastly the hardware resources usage considerations are delivered at the end of this paper.

2021-03-24 PIER B Vol. 92, 19-45, 2021. doi:10.2528/PIERB21020506

Characteristics Mode Analysis: a Review of its Concepts, Recent Trends, State-of-the-Art Developments and its Interpretation with a Fractal UWB MIMO Antenna

Asutosh Mohanty and Bikash Ranjan Behera

In this article, we present a compact and efficient diametrically-fed dual port fractal UWB MIMO antenna for portable handheld wireless devices. The electromagnetic behaviour on conducting body is analyzed through classical approach based characteristics mode analysis (CMA). Their intrinsic characteristics are explored on the basis of (a) modal surface current distributions, (b) narrow/broad bandwidth capability and (c) radiation potentials. Concurrent analysis is persuaded on diametrically-fed dual port fed fractal conducting surface, that provides interesting facets on the combinatory effect of electromagnetic performance and physical behaviour on metallic radiator, metallic ground planes (unconnected/connected) and combination of two aforementioned metallic compact geometries. Theoretical insights are investigated for essential/non-essential modes existing in proposed geometry. The investigation through CMA also gives plethoric information on the feed location of antenna on modal surface currents and similar trends to capture its radiation potentials on the current nulls existing in the physical body. A broad classification of modes is explained, covering the CMA modal dynamics such as (a) characteristics angle (CA), (b) eigen values (EV) and (c) modal significance (MS). These additive parameters in general reflect the resemblance of Q-factor≈B.W. for narrowband/wideband traits, electrically/magnetically coupled energy behaviour and radiative potential for far-field propagation. Thus, in a nut-shell, it can be inferred that `CMA provides physically intuitive guidance for the analysis and designing of antenna structures'. To support the findings highlighted in this particular study, a concise review about the theory of characteristic modes and the practical examples that use such concepts are taken into consideration.

2021-03-19 PIER B Vol. 92, 1-18, 2021. doi:10.2528/PIERB21011501

Capacitance Matrix Revisited

Ivica Smolić and Bruno Klajn

The capacitance matrix relates potentials and charges on a system of conductors. We review and rigorously generalize its properties, block-diagonal structure and inequalities, deduced from the geometry of system of conductors and analytic properties of the permittivity tensor. Furthermore, we discuss alternative choices of regularization of the capacitance matrix, which allow us to find the charge exchanged between the conductors having been brought to an equal potential. Finally, we discuss the tacit approximations used in standard treatments of the electric circuits, demonstrating how the formulae for the capacitance of capacitors connected in parallel and series may be recovered from the capacitance matrix.