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In this paper, a new measurement method is proposed to estimate simultaneously the complex permittivity and the complex permeability for a magneto-dielectric sample, which may contain several layers, using a X-band rectangular waveguide WR90. The Sij-parameters at the reference planes in the rectangular waveguide loaded by a material sample are measured as a function of frequency using the E8634A Vector Network Analyzer. Also, by applying the two-dimensional finite difference in time domain (2D-FDTD), the expressions for these parameters as a function of complex permittivity and complex permeability are calculated even if the sample do not cover all the section of the waveguide. The Nelder-Mead algorithm is then used to estimate the complex permittivity and complex permeability by matching the measured and calculated Sijparameters. This method has been validated by estimating, at the X-band, the complex permittivity and complex permeability of two materials such as FR4 Epoxy and Titanium Carbide powder (TiC). [ABSTRACT FROM AUTHOR]

In this paper, a new measurement method is proposed to estimate the complex permittivity for each layer in a multi-layer dielectric material using a Ku-band rectangular waveguide WR62. The Sij-parameters at the reference planes in the rectangular waveguide loaded by a multi-layer material sample are measured as a function of frequency using the E8634A Network Analyzer. Also, by applying the two-dimensional finite difference in time domain (2D-FDTD), the expressions for these parameters as a function of complex permittivity of each layer are calculated. The Nelder-Mead algorithm is then used to estimate the complex permittivity of each layer by matching the measured and calculated Sij - parameters. This method has been validated by estimating, at the Ku-band, the complex permittivity of each layer of three bi-layer and one tri-layer dielectric materials. A comparison of estimated values of the complex permittivity obtained from multi-layer measurements and mono-layer measurements is presented. [ABSTRACT FROM AUTHOR]

This article demonstrates the feasibility of a novel waveguide dual-mode two-way power divider that is based on an evolved junction having a dedicated T-shaped central matching element (scatterer). This scatterer, with matching sections facing all three ports, provides equal power division and routes the two TE10/TE01 orthogonal modes of a square waveguide toward the corresponding output ports. The proposed design is compact, easily scalable and can be cascaded to obtain $2^{N}$ output ports, being $N$ the number of division stages. Moreover, this structure represents the first waveguide dual-mode two-way reactive power divider (three physical ports) reported in the scientific literature. An exemplary has been manufactured showing an 11% relative bandwidth at 12 GHz and less than −50 dB of cross-coupling. Transmission loss and isolation between output ports are in good agreement with electromagnetic (EM) simulations. [ABSTRACT FROM AUTHOR]

Aquasi-octave bandwidth arbitrary-angle compact waveguide twist using a single matching step is presented. The proposed twist, based on a single intermediate ridge waveguide section that broadens its mono-mode operation, exhibits a similar wave impedance to the rectangular waveguide connected to its ports thus facilitating the reflections minimization in an extended frequency range. An exemplary 45° twist has been manufactured in the 10GHz to 19.3GHz frequency range (~ 64%) for demonstration purposes. The measured data are in concordance with those predicted by the simulation. This result represents, to the authors' knowledge, today's state-of-the-art in terms of compactness and bandwidth performance. [ABSTRACT FROM AUTHOR]

This paper demonstrates the feasibility of very compact and broadband square waveguide bends able to transmit both linear and circular polarizations. A careful control of the bend profile for dual-linear polarization or the use of a new septum-polarizer-like geometry for dual-circular polarization allows to reach full band operation ~34% in the first case and broadband operation ~20% for the second application. Experimental validations show excellent agreement with the theoretical predictions thus effectively extending the previous bandwidth limitations. [ABSTRACT FROM PUBLISHER]

A compact differential phase shifter compact differential phase shifter structure that exhibits both full structure that exhibits both full-band operation and easy mechanical manufacture is presented. I and easy mechanical manufacture is presented. I consists of a rectangular waveguide loaded with consists of a rectangular waveguide loaded with single ridge sections terminated by a unique H single ridge sections terminated by a unique H plane step widening to stand plane step widening to standard waveguide dimensions. Two prototypes of 90º and 180 dimensions. Two prototypes of 90º and 18º differential phase shifters with reference to an differential phase shifters with reference to an empty waveguide of the same length were designed empty waveguide of the same length were designed and tested for the WR75 waveguide band. In both and tested for the WR75 waveguide band. In both cases the differential phase shifter exhibits a cases the differential phase shifter exhibits a maximum measured phase error of ±2.5º and ±3.5º um measured phase error of ±2.5º and ±3.5º respectively, with return losses better than 24 dB respectively, with return losses better than 24 dB and insertion losses lower than 0.06 dB over a and insertion losses lower than 0.06 dB over a >40% bandwidth, which represents state >40% bandwidth, which represents state-of-the-ar achievement for non-dielectric loaded waveguide dielectric loaded waveguide circuits. Furthermore, this structure is well suited more, this structure is well suited for H-plane millimetre-wave integration. wave integration. [ABSTRACT FROM AUTHOR]

An octave bandwidth concept for compact rectangular-to-circular and square-to-circular waveguide transitions based on the use of intermediate octagonal-shaped sections is presented. Apart from its inherent bandwidth capability and spurious mode free operation, this architecture offers some other useful advantages such as easy fabrication, low losses, and extremely short length (less than 0.75 \lambda0, with \lambda0 being the wavelength at the center frequency), which allows their use in the millimeter-wave frequency range. Experimental verification is provided through the measurement of a rectangular-to-circular mode transformer covering more than the super-extended C-band (3.6–7.025 GHz) with 30-dB return loss and 0.1-dB insertion loss, which represents state-of-the-art performance in terms of bandwidth. [ABSTRACT FROM AUTHOR]

A >40% bandwidth fully scalable turnstile-based waveguide orthomode transducer having excellent phase performance is described for the WR75 standard rectangular waveguide. Flexible bandwidth tuning is achieved through the use of an interchangeable stepped scattering element. Reduced height waveguide topology provides a simple, compact, and robust design against mechanical tolerances. The intrinsic broadband nature of half-height E-plane bends and single-step power combiners assures high order mode free increased bandwidth in balanced phase operation. The designed orthomode transducer exhibits a return loss better than 23 dB at any port, an insertion loss less than 0.06 dB, and an isolation of 50 dB over the full bandwidth. Moreover, the phase difference between orthogonal polarizations is lower than 0.7° over the band, thus enabling applications where phase-matched outputs are required. This design has been chosen for the QUIJOTE cosmic microwave background experiment due to its cost-effective, compact design, and high-quality performance as well as being readily scalable to the WR51 and WR28 waveguide bands. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010. [ABSTRACT FROM AUTHOR]

One means of converting the port conditions of a magic-tee into those of a 90° hybrid is to introduce external sections of waveguide at the symmetrical H-plane output ports having the necessary 90° phase difference. The purpose of this article is to describe a number of realizations of such differential phase shifters (DPS), including an exact synthesis procedure not requiring computer optimization. A typical design consists of a capacitively loaded waveguide for one section and an essentially inductive waveguide for the other. The latter is simply a uniform waveguide of reduced width when compared with that of the capacitive section. An example capacitive ridge DPS exhibits a maximum phase error of ±2° over a 20% bandwidth in WR75 waveguide with a return loss of better than 40 dB and an insertion loss <0.06 dB. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009. [ABSTRACT FROM AUTHOR]

This work describes the principle of operation, assembly and performance of one branch of the 44 GHz back end module (REM) for the Planck low frequency instrument (LFI). This subsystem constitutes a fully rep representative branch of the qualification-model version (QM). It includes waveguide to microstrip transition, GaAs pseudomorphic high electron mobility transistor (PHEMT) low noise amplifiers (LNA), bandpass filter, square-law detector and dc amplifier. The fundamentals of the design of the RF part are described and all of the components have been tested individually before integration. Using single tone and wideband noise stimuli, the output voltage has been measured for several input powers, in order to obtain the sensitivity factor of the complete BEM. The effective bandwidth and the equivalent noise temperature have been calculated from the measurements, taking into account the frequency dependence on the noise source and the BEM. Finally the low frequency output power spectrum has been obtained and a maximum 1/f knee frequency around 200 Hz has been measured with a 3 dB output signal video bandwidth above 50 KHz. [ABSTRACT FROM AUTHOR]

This work introduces a simplified multi-aperture iris notch suitable for designing waveguide filters having an extremely improved compactness/rejection ratio, regarding available solutions, and adequate pass-band performances. The proposed iris architecture, analyzed for the first time, exhibits a unique transmission zero in the waveguide mono-mode bandwidth which can be easily located below or above the pass-band. The frequency of this transmission zero is evaluated in terms of the iris dimensions thus providing useful guidelines for designing filters with suitable responses. As a consequence of this simplified topology, any designed filter can be easily manufactured by cutting along its E-field symmetry plane. This strategy greatly improves the filter's insertion loss regarding classical implementations based on more complicated arrangements with piled thin metallic sheets. Two exemplary filters have been designed and tested to be used in a high-performance X-band SATCOM terminal with an 80% size reduction with respect to the existing systems. Both filters covering the Rx (7.25–75 GHz) and Tx (7.9–8.4 GHz) sub-bands show a reflection of −25 dB with insertion losses below 1 dB in the pass-band, whereas they present a very sharp out-of-band rejection of at least 90 dB, that is, a 600 dB/GHz slope at X band. [ABSTRACT FROM AUTHOR]

Very high-power and high-efficiency microwave applications require waveguide structures to combine/divide the power from/to a variable number of high-power solid-state devices. In the literature, among the different waveguide configurations, those capable of providing the maximum output power show a limited relative bandwidth. To overcome this limitation, in this paper a full-band (40%) waveguide power divider/combiner specifically designed for high-power applications (up to several kW) is presented. The proposed structure uses an evolved turnstile junction with a standard rectangular waveguide common port, rotated 45°, with respect to its central axis, to divide/combine the signal to/from the four output/input rectangular ports. The inclusion of an oversized central cavity together with circular and rectangular waveguide impedance transformers at the common port allows the achievement of a full-band operation with excellent electrical performance, while maintaining a very simple and compact configuration. Only two layers of metal are required for the physical implementation of this structure in platelet configuration. A prototype has been designed covering the full Ka-band (26.5–40 GHz), showing an excellent measured performance with around 30 dB of return loss, 0.18 dB of insertion loss, and less than 1.5° of phase imbalance. [ABSTRACT FROM AUTHOR]