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This work describes the principle of operation, assembly and performance of one branch of the 44 GHz back end module (BEM) for the Planck low frequency instrument (LFI). This subsystem constitutes a fully 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.

The PLANCK mission of the European Space Agency is devoted to produce sky maps of the cosmic microwave background radiation. The low-frequency instrument is a wide-band cryogenic microwave radiometer array operating at 30, 44, and 70 GHz. The design, test techniques, and performance of the complete differential radiometer at 30 GHz are presented. This elegant breadboard 30-GHz radiometer is composed of a front-end module (FEM) assembled at the Jodrell Bank Observatory, Cheshire, U.K., and a back-end module assembled at the Universidad de Cantabria, Cantabria, Spain, and Telecomunicacio, Universitat Politecnica de Catalunya, Barcelona, Spain. The system noise temperature was excellent, mainly due to the very low noise performance of the FEM amplifiers, which achieved an average noise temperature of 9.4 K. Index Terms--Cosmic microwave background (CMB), cryogenic, low-noise amplifier (LNA), microwave radiometer, PLANCK low-frequency instrument (LFI).

In this paper a new large-signal metal semiconductor field effect transitor (MESFET) model suitable for applications to nonlinear microwave CAD has been developed and the different phenomena involved in the nonlinear behavior of the transistor have been studied. The importance of this work lies in the fact that multibias starting points (hot and cold device) for pulsed measurements are used to derive a single expression for [I.sub.ds] that describes the dc as well as the small and large signal behavior of the transistor, while taking into account the quiescent point dependence. The algorithms of this new model can easily be incorporated into commercially available nonlinear simulators. The operating-point dependent current [I.sub.ds] is modeled by two nonlinear sources: one of them is the dc characteristic nonlinear equation, and the other represents the differences between dc and pulsed characteristics at every bias point. A complete large-signal model is presented for a 10 * 140 [[micro]meter] GaAs-MESFET chip (F20 process) from the GEC-MARCONI Foundry and a 16 * 250 [[micro]meter] MESFET chip (DIOM process) from the Siemens Foundry. Comparisons have been made between simulations and measurements of pulsed characteristics at different operating points. There was very good agreement between the [P.sub.in]/[P.sub.out] measurements and the MDS simulations using the complete large signal model.

In this work we present a new design of a Wideband Reflection-Type Tunable Phase Shifter (WRTTPS) for smart front-ends applications. The proposed WRTTPS is based on a short-circuited 3- dB/90° Branch-Line Coupler (BLC), whose characteristics can be electronically tuned using Variable Capacitance Diodes (VCDs) at the reflecting load. The combination of a transmission line in series with two parallel varactors enhances the phase shifter performance, and by adding twocrossed microstrip transmission lines to the conventional BLC the bandwidth improves from 17 to 43.34 %. We experimentally implemented the phase shifter and demonstrated that it produces a wide tunable phase range and full transmission within the experimental uncertainty. This novel topology has a fractional bandwidth of around 43.34 % which is greater than 1 GHz at the central frequency 2.63 GHz and provides a relative phase shifting up to 360°. A good agreement has been shown between simulated and measured results. [ABSTRACT FROM AUTHOR]

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 research presents a novel integrated multiband antenna system manufactured and tested for Smart Industries applications. The proposed system consists of a miniaturized planar antenna with multi-arms conceived to cover the most required frequency bands in industry 4.0 such as GPS Band, UMTS Band, ISM Band, LTE Bands, and WiMax Bands. The manufactured design was verified using Arduino programmable circuit board interfaced to SIM900 module and digital sensors for data collection. Depending on the commands received through the human machine interface (HMI) from the end-user, the developed algorithm within the Arduino controls the SIM900 to select the adequate wireless technology to transmit the data and thus reconfigures the antenna to radiate at the target frequency band. The proposed system is easy to deploy inside industrial machines and cost-effective for large scale use. The paper first introduces the main challenges and benefits of miniaturized low-cost antennas systems for Smart Industries and Internet Of Things. Further the parametric study and final dimensions of the design and simulation results are discussed. The proposed design is fabricated, and the measurements of the radiation pattern and return loss are performed. The antenna, with measured maximum gain up to 10 dBi and measured S11 up to -20 dB, exhibits excellent performance for all the frequencies required in Smart Industries such as 1.6GHz, 1.8GHz, 2.3GHz, 2.4GHz, 2.6GHz, 3.5GHz, and 5.8GHz. The proposed antenna system was implemented and tested inside an industrial machine for Yogurt and Milk production and compared to existing commercial solutions. This study shows that the proposed antenna system is suitable for smart factories since it is miniaturized for internal integration, and it has self-frequency-adaptation and low power consumption, allowing the end-user to remotely control and monitor machines and smart devices. [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 article presents the design, simulation and machining of a dual Orthomode Transducer for feeding antenna using waveguide technology. Linear orthogonal polarizations in common port are separated to single linear polarizations in other ports. This device is developed to work in K and Ka bands and could be exploited in satellite communications applications. Also, it is designed to provide good scattering parameters results experienced with simulation tools and real load laboratory measurement. The designed circuit exhibits important results with return losses less than 25 dB, insertion losses in theory of about 0.05 dB as well as a good isolation of 40 dB in both frequency bands of interest (19.4GHz-21.8GHz) and (27GHz-32 GHz). [ABSTRACT FROM AUTHOR]

This paper presents a new design of the fractal multiband antenna structure. The proposed antenna is optimized by using CST-MW studio, this structure is a CPW-Fed antenna which makes it easier to integrate with RF devices. The final validated circuit is designed to operate in the Industrial Scientific and Medical (ISM 2.4 - 2.5GHz), worldwide interoperability for microwave access (WiMAX 3.30 - 3.80 GHz), IMT advanced system (3.40 - 4.20 GHz). The properties of antennas, for example, yield loss, radiation patterns and gain are determined by numerical simulation and measurement. [ABSTRACT FROM AUTHOR]

This paper presents a novel design of a pentagonal-shaped planar dual-band monopole antenna with a modified ground structure. The validated antenna is compact with a size of 57x50x1,6 mm3. It is printed on an FR-4 substrate and fed by a 50 Ohm microstrip line. The final circuit operates in the DCS frequency band at 1.8 GHz and the WiMAX at 3.5 GHz. To achieve such antenna, we have used different optimization methods integrated in CST Microwave Studio. The obtained results are compared with another electromagnetic solver Ansoft's HFSS. After the realization, we have tested and validated this antenna. The measurement results present an agreement with the numerical results. [ABSTRACT FROM AUTHOR]

In this study, we present an implementation of Ultra Wide Band (UWB) Koch Snowflake antenna for Radio Frequency Identification (RFID) applications. The compact antenna, based on the Koch Snowflake shape, is fed by coplanar waveguide (CPW) and by microstrip line with an overall size of 31 x 27 x 1 6mm³. The simulation analysis is performed by CST Microwave Studio and compared with HFSS software. The antenna design exhibits a very wide operating bandwidth of 13GHz (3.4-16.4GHz) and 11GHz (3.5-14.577 GHz) with return loss better than 10 dB for microstrip line antenna and CPW antenna respectively. A prototype of CPW and microstrip antenna was fabricated on an FR4 substrate and measured. Simulated and measured results are in close agreement. The small size of the antenna and the obtained results show that the proposed antenna is an excellent candidate for UWB-RFID localization system applications. [ABSTRACT FROM AUTHOR]

In this paper, we propose a dual band Radio Frequency Identification (RFID) reader antenna. The reader antenna operates at 2.45GHz and 5.8GHz. It has two resonances, the first one in the radiation patch, and the second one in the protruding stub located at the ground plane. The radiating patch of the present compact antenna has the dimensions of 15.6mm x 8.8mm. The matching techniques using stub tuning are adopted in this work. A good impedance bandwidth of 148.48MHz and 204.85MHz has been achieved for 2.45GHz and 5.8GHz respectively while the return loss s11 <-10dB. The proposed antenna is simple and compact in size, providing broadband impedance matching and an appropriate gain, 1.92dBi and 3.385dBi for the lower and upper bands respectively. The comparison between measured and simulated results shows a good agreement, which validates the proposed concept. [ABSTRACT FROM AUTHOR]

In this paper, a star-shaped microstrip patch antenna with modified ground structure consisting of an F-shaped slot printed in the ground is presented. The purpose of this design is to achieve and validate this microstrip multiband antenna. The entire area of the proposed antenna is 50x50mm² and is printed on an FR-4 substrate and fed by a 50 Ohm microstrip line. This antenna has been analyzed and simulated for the WLAN and WiMAX applications. Simulation results show that the antenna has a good matching input impedance bandwidths for, S11<=-10 dB, covering the WLAN at 2.4/5.2 GHz and WiMAX at 3.5 GHz. Simulation has been done by using three different electromagnetic solvers for comparison CST-MW, Ansoft's HFSS and ADS. After the realization, we have tested and validated this antenna. The measurement results of the antenna present a good agreement with the numerical results. [ABSTRACT FROM AUTHOR]