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The determination of a small number of samples to characterize the antenna far field with a controlled accuracy is addressed. The radiation operator that maps the equivalent currents to the far field is built from the outer dimensions of the antenna under test and is discretized into the so-called radiation matrix using the methods of moments. This matrix is approximated up to the measurement accuracy by truncating its singular value decomposition accordingly. This operation enables to construct numerically a reduced basis of the radiated fields. The dimension of this basis and consequently the number of field samples is shown to be determined by the area of the equivalent current convex surface, in agreement with the fundamental works on the minimum non-redundant samplings. The influence of the field sampling strategy and noise on the far-field pattern reconstruction are investigated in order to determine a realistic small number of field samples. Finally, the characterization of two radiating structures from the so-derived reduced number of samples validates experimentally the proposed approach and demonstrates its practical relevance.

A vectorial modal method is presented based on transverse magnetic and transverse electric mode expansion, which significantly simplifies the evaluation of the operator matrix. The method, which features a true open boundary condition, is introduced for an orthogonal curvilinear coordinate system with the specific examples of circular and elliptical geometries presented. We validate the method by considering challenging problems, such as the calculation of spontaneous emission rates, of modal reflection coefficients and of the effect of the emitter spatial misalignment on the spontaneous emission β factor. Results are compared with literature.

We present a numerical investigation of the performance of the micropillar cavity single-photon source featuring an elliptical cross section. While ellipticity serves to establish polarization control of the emitted photons, it introduces a trade-off due to reduced coupling to a Gaussian profile in the far field and the need for significantly increased pumping power when a resonant excitation pumping scheme is implemented. Starting from a circular micropillar, we identify optimum geometrical parameters leading to a maximum polarized coupling efficiency of 0.90 to a Gaussian profile in the far field combined with a modest relative increase in the pump power of 16 dB.

The desire to reduce the mass per unit length and to increase phase stability of coaxial radio-frequency (RF) power cables for space application motivates a new design idea, namely to replace solid dielectric with a periodic chain of hollow pearls. The design of the dielectric pearls must allow for bending flexibility of the cable even if they are made from a stiff material such as silicon glass. An important requirement of RF power cables for space applications is their phase stability, which is influenced by the material-dielectric-constant tolerance over a large temperature range as well as by changes in geometry. This paper presents an original closed-form model based on rigid-body motion to predict the kinematic response of dielectric pearls to the bending of the cable. Particularly, the model maps the eccentricity of the inner and outer conductors with respect to each other and the axial strain of the bent cable along its centreline. The model results indicate that mass reductions of the periodic hollow-pearl design over conventional solid PTFE dielectrics are significant.

In this contribution, open boundary elliptical nanophotonic structures are modeled and simulated via a full-wave vectorial modal method. Analytical basis modes based on the splitting of transverse magnetic and transverse electric fields are constructed. The special basis modes used in the implementation lead to analytical coupling integrals, and therefore fast and efficient simulations.

Phaseless near field measurements are an attractive solution to characterize antennas at reasonable costs, especially at high frequencies. The source reconstruction method is applied to compute the equivalent currents representing the antenna under test using two phaseless surface scans. The reconstruction of these equivalent currents uses recently proposed phase retrieval algorithms that mitigate some of the shortcomings of existing techniques with an automatic settings of the initial guess. In addition to be readily available and easy to be plugged in electromagnetic modeling tools, these routines exhibit good phase recovery performances and robustness with respect to noise, separation between scanning planes and near field sampling step. The proposed procedure is applied to determine the far field radiated by various types of antennas operating in different frequency bands from phaseless near field scans. Experimental validations of two radiating structures show its potentialities and interest.

In this work, ohmic losses present in arbitrarily shaped waveguide-based structures are rigorously considered. For such purpose, a software tool based on the perturbation of the boundary conditions on the metallic walls of the waveguides combined with an Integral-Equation (IE) analysis technique is proposed. In order to obtain the modal chart of waveguides with arbitrary cross-section, the Boundary Integral – Resonant Mode Expansion (BI-RME) method is also employed. To show the advantages of the proposed technique a computer-aided design software package based on this modal analysis tool has been applied to predict the propagation loss effects in complex waveguide components.

This paper is a preprint of a paper submitted to IET Microwaves Antennas and Propagation and is subject to Institution of Engineering and Technology Copyright. If accepted, the copy of record will be available at IET Digital Library, The accurate consideration of propagation losses in arbitrarily shaped waveguide-based structures is studied in this paper. For such a purpose, a software tool based on the perturbation of the boundary conditions on the waveguide metallic walls and on the boundary integral resonant mode expansion method has been developed. To show the advantages of the proposed technique with respect to the classic power-loss method, the complex propagation wavenumbers of a double ridge and an elliptical waveguide have been first computed and compared with results of a commercial software based on the finite element technique. Next a circular, a sectorial shaped and a triangular shaped waveguide have been considered. Then, a computer-aided design software package based on this modal analysis tool has been applied to predict the propagation loss effects in complex waveguide structures, such as an evanescent mode ridge waveguide filter, a traditional dual mode filter with circular cavities and a twist component for K-band applications.

The accurate consideration of propagation losses in arbitrarily shaped waveguide-based structures is studied in this paper. For such a purpose, a software tool based on the perturbation of the boundary conditions on the waveguide metallic walls and on the boundary integral - resonant mode expansion method has been developed. To show the advantages of the proposed technique with respect to the classic power-loss method, the complex propagation wavenumbers of a double ridge and an elliptical waveguide have been first computed and compared with results of a commercial software based on the finite element technique. Next a circular, a sectorial shaped and a triangular shaped waveguide have been considered. Then, a computer-aided design software package based on this modal analysis tool has been applied to predict the propagation loss effects in complex waveguide structures, such as an evanescent mode ridge waveguide filter, a traditional dual mode filter with circular cavities and a twist component for K-band applications.