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- Johan C. E. Sten, Arto Hujanen, PÃ¤ivi K. Koivisto
- 2001

Expressions are derived for the smallest achievable radiation quality factor ( ) of an electrically small antenna in front of a conducting plane. Applying the low-frequency approximation to the source region involving an electric or a magnetic point dipole plus their images behind the plane, an expression is formed for the field in the radiation zone. Theâ€¦ (More)

- Arto Hujanen, Johan C. E. Sten
- Annales des TÃ©lÃ©communications
- 2001

In this work the scattering of plane waves from a finite sized perfectly conducting wedge as a .function of its opening angle and the width of its faces is studied using the combination of physical optics (po) and the physical theory of diffraction (PTD). To find out under which circumstances the PTD contribution is significant compared to the Po, the ratioâ€¦ (More)

A transformation linking spherical multipole fields with generalized spheroidal multipole fields is derived. Applications including the inverse diffraction problem for spherically-scanned near field data for sources that due to conformal considerations are efficiently described using spheroidal (either oblate or prolate) volume support regions are discussedâ€¦ (More)

A key structure in so-called metamaterial mediums is the elementary split-ring resonator. We consider in this paper the lowfrequency electromagnetic scattering by a split-ring particle modelled as a perfectly conducting wire ring, furnished with a narrow gap, and derive analytical solutions for the electric and magnetic dipole moments for different kinds ofâ€¦ (More)

INTRODUCTION Recently, we have investigated the classical inverse source problem of reconstructing an unknown radiating source from knowledge of the exterior field it generates, with emphasis on sources whose support is contained within a spheroidal volume which can be oblate or prolate [1]. This facilitates the source inversion treatment of a variety ofâ€¦ (More)

- Johan C. E. Sten, Arto Hujanen
- Annales des TÃ©lÃ©communications
- 2006

- Johan C. E. Sten, Daniel Sjoberg
- 2009 3rd European Conference on Antennas andâ€¦
- 2009

The elementary split ring resonator is a key structure in so-called “metamaterial” mediums. In this presentation, low-frequency electromagnetic scattering by a split ring, modelled as a perfectly conducting wire ring furnished with a narrow gap, is presented and analytical results are given for the electric and magnetic dipole moments forâ€¦ (More)

The magnetic energy and inductance of current distributions on the surface of a torus are considered. Specifically, we investigate the influence of the aspect ratio of the torus, and of the pitch angle for helical current densities, on the energy. We show that, for a fixed surface area of the torus, the energy experiences a minimum for a certain pitchâ€¦ (More)

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