Leaky-Wave Radiation From 2-D Dielectric Lattices Excited by an Embedded Electric Line Source

Abstract

This paper presents an analytical and numerical investigation of the radiation features of an interesting class of electromagnetic bandgap (EBG) structures excited by an electric line source. The radiation from two-dimensional (2-D) lattices made with lossless dielectric cylinders, typically optimized by using the Bloch analysis of the corresponding 2-D photonic crystals, are originally investigated in terms of leaky waves. A thorough modal analysis of open waveguides, composed by a finite number of periodic chains of circular dielectric rods, is presented that shows a multiplicity of bound and leaky modes. Two radiation windows are identified and the relevant directive features are described in terms of properly excited dominant leaky modes. The possible excitation of higher order leaky modes and guided modes has been carefully considered, by also capturing the relevant residue contributions in a nonspectral representation of the excited fields. The final results on radiated fields by realistic truncated structures, obtained by ad-hoc software as well as full-wave EM simulators, are in excellent agreement with those predicted by the proposed leaky-wave approach.

Highly Directive Leaky-Wave Radiation in 2-D Dielectric Photonic Crystals

“…Directive radiation by elementary sources embedded in PCLWAs is related to the presence of a band-gap between dielectric and air bands in the corresponding 2-D PC lattices and it is observed at the lower edge of the air band [3]- [5], [15]. Hence a preliminary Bloch-wave analysis of the DRPC and HPC 2-D lattices is needed to fix geometrical and physical parameters of the PCLWA.…”

“…2(a), formed by N y = 12 circular voids in the transverse y-direction). Here, adopting the leaky-wave approach proposed in [15] and using the tailored numerical procedure developed in [18], the directive features of such kind of radiators have been investigated. A complete analysis, including structures with lossless dielectric rods in free space as well as the dual configuration consisting of circular voids in a hosting lossless dielectric medium, where both even and odd number of rods or voids are considered, is performed.…”

“…By placing an electric line source in the PMC bisection planes or slightly above the PEC bisection planes, where maxima of the electric fields of the leaky AM 0 are present for the different geometries investigated (see the black dots for the four different cases in Fig. 2(b)), only the leaky AM 0 is excited [15] and directive radiation with two beams at both sides of the open waveguide can be obtained. In Fig.…”

“…Then a leaky-wave formalism was used to explain the radiative phenomenology, mainly when homogenized structures were considered [11], [12], but also in PCs and quasicrystals [13], [14]. Recently, the radiation mechanism of 2-D dielectric lattices has been thoroughly examined in terms of leaky waves [15], showing that a joined Fig. 1.…”

On the input impedance of probe‐fed electromagnetic bandgap antennas based on lattice modes

“…It is identified more clearly in Figure 3b, where the three‐dimensional dispersion diagram of the lattice of Figure 3a is plotted. A mode with k x = π / a and k y = 0 can also propagate at the same frequency, but it has been shown that single modes can be selectively excited in a square lattice [31]. Any lattice mode different from the radiation one will be referred to as spurious or unwanted mode.…”