Nonradiative Dielectric Guides Research Articles

Leaky Wave-Guide Based Dielectric Resonator Antenna for Millimeter-Wave Applications

In this paper, a leaky wave antenna based on the parallel non-radiative dielectric guide (NRD) has been proposed. This novel design uses two parallel dielectric strip waveguides having a dielectric constant of 2.2 are placed over a substrate of the dielectric constant of 2.55 and both are separated by a ground plane. The upper structure is bounded by deflating conducting strip having distance less than λ0/2. The leakage from this antenna is in the form of surface wave concentrated more in the broadside direction rather than usual endfire or off broadside direction. It has been observed the proposed radiating structure has radiation efficiency of 82%, the peak gain of 5.94 dB with narrow impedance bandwidth, and the resonating frequency at 13.59 GHz, 13.43 GHz, and 13.93 GHz. A comparative analysis is made by increasing the height of the dielectric strip to increase the number of modes. This leaky-wave structure based on a non-radiative dielectric (NRD) guide can be a suitable candidate for the device to device (D2D) communication in the millimeter-wave band.

Propagation Characteristics of a Novel NRD Guide with Double-Layer LHM Slab

A new waveguiding structure based on NRD (Nonradiative Dielectric) guide with a double-layer LHM (Left Hand Material) slab is carefully investigated. Rigorous multi-mode network treatment combining with mode matching method is carried out to analyze the propagation characteristics of the structure. Theoretical analysis results reveal that depending on the choice of permittivity and permeability of the two dielectric slabs, the guiding structure is of series distinct and interesting properties, such as anomalous dispersion, opposite polarization modes coupling, and the existence of complex mode. Besides, the new configuration can also be used as a leaky wave antenna working in the dominant or the first higher order mode. All these particular features create various applications in electromagnetic engineering.

Electric field integral equation approach for accurate modeling of transmission loss properties and leakage phenomena in NRD-guide of arbitrary cross section

An electric field integral equation method has been developed for accurately modeling both transmission losses and leakage behaviors along nonradiative dielectric (NRD) guides of arbitrary cross-sectional shape and arbitrary inhomogeneous dielectric permittivity. The method is verified by comparing its modeling results with measured ones as well as with results obtained from a mode-matching method for bench-mark structures. The leakage properties of elliptical NRD guides and also the complete losses in trapezoidal NRD guides are studied in detail for the first time to demonstrate the advantages of the new method. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007.

Leaky Characteristics of Modified NRD Guide with Finite Parallel Plate Length

Leaky wave characteristics of modified NRD (Nonradiative Dielectric) guide with parallel plate length are systemically investigated. A technique is used to investigate the leaky property of the guide structure, whichis formulated by effectively combining the multimode network theory with the mode-matching method. In the paper, two phenomena are carefully studied: First, the asymmetric position of the dielectric rod generates a leaky hybrid mode that could produce cross talk between components of the circuit. Second, when the length of metallic plate is finite, another type of leaky mode creates which influences and even couples to the normal leaky guide mode under appropriate circumstances.

Analysis of Inhomogeneously Dielectric Filled Cavities Coupled to Dielectric-Loaded Waveguides: Application to the Study of NRD-Guide Components

In this paper, we present two contributions. First, we develop a computationally efficient technique for the full-wave characterization of inhomogeneously dielectric-filled cavities connected to inhomogeneously dielectric-loaded waveguides. This method is based on the expansion of the electromagnetic field within the cavity in terms of their solenoidal and irrotational modes. The presented formulation allows the treatment of hybrid modes in the waveguide ports, where the definition of a characteristic modal impedance or admittance is not possible. The multimode scattering matrix of the structure is computed throughout an efficient implementation of the orthonormal-basis method for the calculation of the cavity modes. Secondly, we have employed the present technique for the analysis and design of nonradiative dielectric (NRD) guide components and discontinuities. Moreover, the application of the bi-orthonormal-basis method for the calculation of the full-spectrum of NRD guides is demonstrated as being a very efficient approach for the rigorous treatment of such guides. Next, an efficient computer-aided design tool has been developed for the analysis of complex NRD-guide circuits. We have compared our simulations with theoretical and experimental results available in the technical literature, fully validating our software. This code has been employed for the specific analysis of a linear continuous taper to match two NRD guides with different widths, demonstrating a considerable reduction of the return losses over a wide frequency band. Finally, stopband and bandpass NRD-guide filters based on an electromagnetic-bandgap concept are presented.

Selection of proper modes of an NRD guide using a perturbing boundary

A novel method to remove unwanted modes in the analysis of nonradiative dielectric (NRD) guide is proposed. Those modes are originated by the compulsory truncation of an infinite boundary to restrict finite-element domain. It will be shown that unwanted modes can be filtered out by a special boundary concept named a perturbing boundary condition. This method is applied to obtaining the propagation constant of inhomogeneous NRD guides and NRD guides with a trapezoidal cross section of which analytic solutions do not exist.

Spectral-domain Green's function of magnetic type for NRD guides and H-guides

Nonradiative dielectric guides and H-guides are widely used in millimeter-wave integrated circuits and antennas. To analyze the behavior of discontinuities, obstacles, and slots in such structures, an increasingly used mathematical formulation is the integral-equation approach, for which Green's function is required. Here, an efficient programmable full-wave Green's function, due to a magnetic-current element placed inside the dielectric layer, is derived in the spectral domain. In the derivation procedure, the field is divided into two parts: the incident and scattering fields. The contribution of the surface wave is included in the scattering part, while the singularity, when the field and source points are the same, is presented in the incident field part. By doing so, one can deal with the singularity caused by the source and surface-wave poles encountered in the integration separately and freely. The Green's function is then used to analyze the radiation characteristics of a single transverse slot in upper plate of the H-guide. The results obtained are in good agreement with experimental data available in literature.

Analysis and measurement of NRD-guide leaky wave coupler in Ka-band

A new structure for a nonradiative dielectric (NRD) waveguide directional coupler has been developed. The structure combines two NRD guides and a dielectric slab guide in order to utilize a leakage mechanism for coupling. The coupling depends on this leaky mechanism, but not on field interactions as in a conventional proximity coupler. A theoretical formula for calculation of the decay constant is derived. The field along the NRD guide and the decay constant are measured at Ka band (35 GHz) and compared with the theoretical data. Reasonable agreement between the measured and theoretical data is found.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>