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3 Journal of Telecommunications and Information Technology

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A wideband smart antenna employing spatial signal processing

Uthansakul M., Białkowski M. E.

Journal of Telecommunications and Information Technology

2007

nr 1

13-17

A smart antenna with capability of beam steering in azimuth over a wide frequency band using only spatial signal processing is presented. Filters and tapped-delay networks employed in conventional wideband linear arrays are avoided by using a two-dimensional rectangular array structure. In this array, only constant real-valued weighting coefficients, realized with amplifiers or attenuators, are used to form a desired radiation pattern. In order to estimate direction of arrival of a wideband signal, the MUSIC algorithm in conjunction with an interpolated array technique is applied. In the interpolated array technique, a composite covariance matrix is generated, which is a simple addition of covariance matrices of narrowband virtual arrays, being stretched or compressed versions of a nominal array. A working prototype of this wideband array is presented. Its operation is assessed via full EM simulations and measurements.

Spatial power combiner using a planar active transmitarray of stacked patches

Tai F.-C. E., Białkowski M. E.

Journal of Telecommunications and Information Technology

2005

nr 2

45-49

An X-band spatial power combiner, which uses a planar transmitarray (TXA) of orthogonally polarized stacked microstrip patches integrated with input and output ports of transistor amplifiers is described. In order to obtain an increased operational bandwidth, the unit cell of the combiner with various stacked patch (SP) configurations is investigated. The configuration showing the smallest insertion losses is chosen for developing a TXA. The constructed spatial combiner includes a 4×4 cell TXA placed between two hard horn antennas. Its performance is assessed experimentally in terms of amplification gain and combining efficiency.

A broadband uniplanar quasi-Yagi antenna - parameter study in application to a spatial power combiner

Białkowski M.E., Song H.J., Kabacik P.

Journal of Telecommunications and Information Technology

2001

nr 4

41-47

A parameter study is performed of a broadband uniolanar quasi-Yagi antenna with regard to its design and use in a spatial power combiner. A 3D full-wave electromagnetic field analysis is applied to identify parameters, which mostly affect the design frequency and operational handwidth of this antenna. Optimal design conditions are determined. Using these design criteria a passive spatial power combiner employing trays of back-to-back connected quasi-Yagi antennas is developed. This combiner is investigated in terms of insertion losses and field uniformity, which are key factors in obtaining high power combining efficiency.