Dielectric-filled Rectangular Waveguide Research Articles

Design of a Compact Omnidirectional Leaky-Wave Antenna Fed by Higher Order Mode

This article presents a novel leaky-wave antenna (LWA) based on a dielectric-filled rectangular waveguide (RWG) and fed by a higher order mode. The proposed quasi-uniform LWA has a compact configuration that is suitable for microwave applications, featuring the omnidirectional radiation patterns and low cross-polarization. In the frequency band of interest, the higher order mode, i.e., the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode, performs as a fast wave in the proposed quasi-uniform LWA, radiating via the transverse slots etched on the walls. The advantage of the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode for LWA applications is analyzed and demonstrated. This higher order mode is excited via a mode convertor from an inline coaxial line to the dielectric-filled RWG. For the reduction in sidelobe levels at high frequencies, −25 dB Taylor amplitude distribution is applied to the etched slots. The dielectric-filled LWA with the inline coaxial feeding is fabricated and measured. The measurement is consistent with the simulation, showing frequency-driven beam-scanning capability with low cross-polarization in the elevation plane. The simulated and measured radiation patterns in the azimuth plane illustrate the omnidirectional radiation patterns and thus confirm the radiating performance of the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode in the proposed LWA. The advantages of the scanned beams and omnidirectional radiations are promising for radar systems.

General Mapping Between Complex Spatial and Temporal Frequencies by Analytical Continuation

This article introduces a general technique for intermapping the complex spatial frequency (or propagation constant) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\gamma =\alpha +j\beta $ </tex-math></inline-formula> and the temporal frequency <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\omega = \omega _{\text {r}}+j\omega _{\text {i}}$ </tex-math></inline-formula> of arbitrary electromagnetic media and structures. This technique is based on the analytic property of complex functions that describe physical phenomena; it invokes the analytic continuity theorem to assert the unicity of the mapping function and builds this function from known data within a restricted domain of its analyticity by curve fitting to a generic polynomial expansion. It is not only applicable to canonical problems admitting an analytical solution but also to <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">general</i> medium or structure problems, from eigen- or driven-mode full-wave simulation results. The proposed technique is demonstrated for several systems, namely, an unbounded lossy medium, a dielectric-filled rectangular waveguide, a periodically loaded transmission line, a 1-D photonic crystal, and a series-fed patch (SFP) leaky-wave antenna (LWA), and it is validated either by analytical results or by full-wave simulated results.

Triple‐mode bandpass filter

triple‐mode bandpass filter

A Simplified Design Inline Microstrip-to-Waveguide Transition

A simplified design of an inline transition between microstrip and rectangular waveguide is presented in this paper. The transition makes use of a dielectric filled rectangular waveguide (DFRW) as an intermediate step, which simplifies manufacturing and allows for an analytical design. The behavior of the transition has been experimentally validated in the W-band by means of a back-to-back configuration. Good performance has been achieved: a return loss greaterthan 10 dB and mean insertion loss lower than 1 dB.

Wide-Beam SIW-Slot Antenna for Wide-Angle Scanning Phased Array

In order to enhance the scanning range of planar phased arrays, a planar substrate integrated waveguide slot (SIW-slot) antenna with wide beamwidth is proposed in this letter. The proposed antenna is fabricated on a single-layer substrate, which is fully covered with a metal ground on the back. The SIW works like a dielectric-filled rectangular waveguide working in the ${TE}_{10}$ mode. There are four inclined slots etched on the top metal layer following the rules of rectangular waveguide slot antenna. The electric fields in the slots work as equivalent magnetic currents. As opposed to normal microstrip antennas, the equivalent magnetic currents from the slots over a larger metal ground can radiate with a wide beamwidth. Its operating bandwidth is from 5.4 to 6.45 GHz with a relative bandwidth of 17.7%. Meanwhile, the 3-dB beamwidth in the ${x}{z}$ -plane is between 130° and 148° in the whole operating band. Furthermore, the SIW-slot element is employed in a ${1} \times {8}$ planar phased array. The measured results show that the main lobe of phased array can obtain a wide-angle scanning from $- {\hbox{71}}^\circ $ to 73° in the whole operating band.

THB‐filled monolithic rectangular waveguides for millimeter wave applications

A monolithic wafer-level dielectric-filled rectangular waveguide for millimeter-wave applications is designed and fabricated. Unlike the existing wafer-level rectangular waveguides that are based on hybrid integration techniques to assemble the waveguide, the three-step fabrication process of the proposed waveguide enables the simultaneous monolithic fabrication of the dielectric-filled waveguide as well as planar circuitry on one substrate. The maximum temperature during the entire fabrication process stays lower than 200 °C which is desirable for integrated circuit (IC) fabrication. Besides, the RF performance of the presented waveguide only depends on the RF properties of the filling dielectric not the carrier substrate (as in the case of Substrate Integrated Waveguides), which makes it ideal for silicon micro-fabrication technology. A negative-tone thick photoresist called THB N151 which can reach a thickness of 90 μm by single spinning is used and characterised. The results show a relative permittivity of ɛr′ = 3 and a loss tangent of tanδ = 0.018 for THB 151 which surpasses the RF performance of the highly used SU8 photoresist. An average insertion loss of 0.21 dB/mm is measured for the THB-filled waveguide for the frequency range of 35–50 GHz. To perform the wafer-level measurements, the waveguide is integrated with CPW to rectangular transition. Furthermore, it has been illustrated that other monolithic waveguide structures such as Turn or Y-junction can be potentially developed by using the proposed solution.

Accurate and efficient design technique for wideband substrate integrated waveguide directional couplers

In this article, we present an efficient technique for the accurate design of wideband substrate integrate waveguide directional couplers. By tapering the coupling section, the bandwidth of substrate integrated waveguide (SIW) directional couplers can be enlarged. Two design aspects are involved in this approach. First, the even-mode propagation constant in the tapered coupling section is accurately extracted with the help of a numerical thru-reflect-line calibration technique. Then, it is fitted into the model of a uniform dielectric-filled rectangular waveguide and thereafter extrapolated to the operation range of the odd mode. Second, equivalent circuit models of the waveguide bifurcation effects are also presented together with parametric values. Based on the results of extraction, a 90° 3-dB directional coupler is developed to validate the proposed design approach. To achieve the reverse phasing at two output ports, the prototyped 90° 3-dB directional coupler is subsequently integrated with a novel broadband fixed phase shifter developed with the SIW technology, of which a systematic synthesis procedure has been proposed in this article. Measured performance of both 90° and 180° 3-dB couplers confirms the accuracy of our proposed design approach. This kind of wide-band directional coupler can find applications in wideband power dividing/combining circuits within a single-layer platform. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012. © 2012 Wiley Periodicals, Inc.

Modal Analysis of Dielectric-Filled Rectangular Waveguide With Transverse Slots

The dispersion relations and modes for a dielectric-filled rectangular waveguide with transverse slots are investigated. The differences between the air-filled and the dielectric-filled rectangular waveguides with transverse slots are analyzed. The dielectric-filled rectangular waveguide with transverse slots supports a leaky waveguide mode, a surface-wave mode and a proper waveguide mode. The complex propagation wavenumber is calculated by enforcing an aperture magnetic field integral equation using either a space-domain approach or a spectral-domain approach. The physical significance of the solutions is explained. The theoretical results agree very well with the results from HFSS simulation.

Half-Mode Substrate Integrated Waveguide Transverse Slot Array Antennas

Transverse slot array antennas fed by a half-mode substrate integrated waveguide (HMSIW) are proposed and developed in this paper. The design concept of these new radiating structures is based on the study of the field distribution and phase constant along the HMSIW as well as on the resonant characteristics of a single slot etched on its top conducting wall. Two types of HMSIW-fed slot array antennas, operating, respectively, in X-band and Ka-band, are designed following a procedure similar to the design of slot array antennas fed by a dielectric-filled rectangular waveguide. Compared with slot array antennas fed by a conventional rectangular waveguide, such proposed HMSIW-fed slot array antennas possess the advantages of low profile, compact size, low cost, and easy integration with other microwave and millimeter wave planar circuits. It is worth noting that the width of HMSIW slot array antennas is reduced by nearly half compared to that of slot array antennas fed by a substrate integrated waveguide.

Novel TE/sub 10δ/ rectangular-waveguide-type resonators and their bandpass filter applications

New dielectric-filled rectangular-waveguide-type TE/sub 10/spl delta// resonators are presented. A dielectric-filled rectangular waveguide section (WGS) has inductive impedance at the open-end faces. Using this property and the frequency dependency of the wave impedance of the WGS, we calculated the resonant frequency and the slope parameter of the waveguide-type resonators. The resonant frequency depends strongly on the width of the WGS and loosely on the height and the length. The calculated resonant frequencies agree well with measured data. One of the proposed bandpass filters shows highly reduced spurious up to three times the center frequency. Quality factors of the resonator and effects of a housing are also discussed.

Mode-Matching Analysis of Waveguide T-Junction Loaded With an H-Plane Dielectric Slab - Abstract

This paper presents a full-wave mode-matching analysis of a rectangular waveguide T-junction partially loaded with an H-plane dielectric slab. First, the longitudinal section electric (LSE) and longitudinal section magnetic (LSM) modes in an H-plane dielectric-filled rectangular waveguide are obtained. Second, the dielectric-loaded T-junction is then divided into four regions and their electromagnetic fields are expanded into the summation of their modal functions using the resonator method. Finally, a mode-matching process for the tangential field components across regional interfaces is carried out to derive the generalized scattering matrix of the waveguide T-junction. Using the cascading connection technique of generalized scattering matrix, various waveguide couplers and power dividers/combiners with H-plane dielectric slabs can be easily analyzed and designed. Numerical results are presented and compared with those obtained by measurement or Ansoft's HFSS. Good agreement is observed.

35 GHz Varactor analogue phase modulator in integrating waveguide technology

Design method, fabrication process and measurement results of a linear analogue phase modulator in Ka-band with abrupt varactor diode are presented. The modulator was realised in integrating waveguide technology, which is based on a completely dielectric-filled rectangular waveguide. The 180° phase shift over the frequency band 34.3?35.4 GHz has been received with phase nonlinearity less than 3.5% and insertion loss of 3 ± 0.4 dB.

Analysis of Dielectrc-Filled Waveguide Coupling to Plasmas in the ICRF

Dielectric-filled waveguides may be advantageous for heating reactor-grade tokamak plasmas, due to their compactness and power-handling capability. We present a theoretical analysis of coax excitation and plasma impedance for a dielectric-filled rectangular waveguide. The plasma reflection coefficient is obtained by matching plasma and waveguide fields at the interface. The numerical results show that the reflection coefficients can be made small by careful tailoring of the waveguide dimensions to the density profile for heating at the second or third harmonic of deuterium. We present a scattering matrix approach for the design of a coaxial feed to match the waveguide in the presence of a wide range of plasma loading. For a waveguide filled with a high permittivity dielectric, a shorted probe gives better coupling than an open-ended probe.