Sven Nordebo

A semi-infinite quadratic programming algorithm with applications to array pattern synthesis

This paper presents a new extended active set strategy for optimizing antenna arrays by semi-infinite quadratic programming. The optimality criterion is either to maximize the directivity of the antenna or to minimize its sidelobe energy when subjected to a specified peak sidelobe level. Additional linear constraints are used to form the mainlobe. The design approach is applied to a numerical example that deals with the design of a narrow-band circular antenna array for the far field.

Optimum Pole Position for Digital Laguerre Network with Least Square Error Criterion

The digital Laguerre network has been studied as a means of implementing filters with a much smaller number of coefficients compared to Finite Impulse Response (FIR) filters. This paper considers the selection of the optimum pole for the Laguerre network. We propose a new effective algorithm for solving the optimum pole selection problem. Simulation results are presented, and comparison between the Laguerre structure and FIR filter structure are given.

Application of infinite dimensional linear programming to FIR filter design with time domain constraints

Previously the envelope-constrained filtering problem was formulated as designing an FIR filter such that the filters L/sub 2/ norm is minimised subject to the constraint that its response to a specified input pulse lies within a prescribed envelope. We recast this filter design problem as a frequency-domain L/sub /spl infin// optimization problem with time-domain constraints. Motivations for solving this problem are given. Then infinite dimensional linear programming techniques are used for the design of the required FIR filter. For illustration, we apply the approach to a numerical example which deals with the design of an equalization filter for a digital transmission channel.

Chebyshev Optimization of Circular Arrays

The lobe design of a narrow-band antenna array is formulated as a complex Chebyshev optimization problem. Previously, the solution of similar problems have been approximated using various techniques including conventional finite-dimensional linear programming. In this paper, recently developed semi-infinite linear programming techniques employing simplex extension algorithms are used to design the required antenna array.

Design of linear phase FIR filters with recursive structure and discrete coefficients

We consider a class of FIR filters defined by the first order difference routing digital filter (DRDF) structure and sums of two powers-of-two coefficients. A novel design method is developed for constructing high quality filters with reference to the min-max error criterion. This method is highly efficient in terms of computational time. Simulation studies show a large improvement over existing methods such as quantization. In some cases, the peak ripple magnitude over the stop and pass bands is reduced by up to 13 dB over the quantization method. These results are achieved even for cases involving small number of delays.

Design of Antenna Array Using Dual Nested Complex Approximation

This paper presents a new practical approach to complex Chebyshev approximation by semi-infinite linear programming. By the new front-end technique, the associated semi-infinite linear programming problem is solved exploiting the finiteness of the related Lagrange multipliers by adapting finitedimensional linear programming to the dual semi-infinite problem, and thereby taking advantage of the numerical stability and efficiency of conventional linear programming software packages. Furthermore, the optimization procedure is simple to describe theoretically and straightforward to implement in computer coding. The new design technique is therefore highly accessible. The algorithm is formally introduced as the linear Dual Nested Complex Approximation (DNCA) algorithm. The DNCA algorithm is versatile and can be applied to a variety of applications such as narrow-band as well as broad-band beamformers with any geometry, conventional Finite Impulse Response (FIR) filters, analog and digital Laguerre networks, and digital FIR equalizers. The proposed optimization technique is applied to several numerical examples dealing with the design of a narrow-band basestation antenna array for mobile communication.

Application of infinite dimensional linear programming to IIR filter design with time domain constraints

Recently developed infinite dimensional linear programming techniques are used for the design of recursive filters with complex Chebyshev error criteria and time-domain constraints. The approach is applied to a numerical example which deals with the design of a Laguerre network as an equalization filter for a digital transmission channel.