A novel positioning algorithm is described for locating wireless sensor nodes in the extreme multi-path conditions encountered in industrial storage vessels. Here, pulse leading edge detection is combined with high-resolution spatial diversity, to facilitate both precision positioning and cumulative error estimation. The 2-D prototype described within may be readily adapted for 3-D full scale commercial applications.
We describe the in-phase/quadrature covariance-matrix representation of the uncertainty in complex vectors, and transformations between this representation and the magnitude/phase and real/imaginary uncertainty representations.
A new type of Ka band (26 to 36 GHz) 180 degree phase switch (bi-phase modulator) monolithic microwave integrated circuit has been developed for the EC funded FARADAY radio astronomy project. This integral component forms part of a chip set for a very low noise switching radiometer operating at a temperature of approximately 15 K. To maximize the sensitivity of the radiometer lattice-matched indium phosphide HEMT technology has been used: all of the active components of the radiometer, with the exception of the detectors, have been manufactured on a single wafer process. Design principles are described, together with a comparison of modeled and measured results. The results show an average insertion loss of 3.5 dB, return loss of better than 10 dB and an average phase difference close to 170 degrees 10 degrees the 26-36 GHz band.
A sideband generator based on phase modulation is presented. The sideband generator consists of a Schottky varactor diode mounted in a WR-10 waveguide tuned resonant circuit. A microwave pump signal modulates the phase of the reflection coefficient the circuit presents to an incident millimeter-wave signal. This proof-of-principle circuit has shown a sideband conversion loss of 9 dB and bandwidth of nearly 10% at 80 GHz. These results represent significant improvements over the performance of sideband generators based on resistive mixing in corner-cube mounts.
In this work, we present a 3-bit K-band distributed phase shifter circuit that employs microelectromechanical systems (MEMS) capacitive switches. The measured results demonstrate an average 1.7 dB insertion loss at 26 GHz with return loss better than -7 dB. Insertion phase shifts of all switching states are measured and show phase error less than 8.50 for all states. The low loss K-band 3-bit phase shifter demonstrated here can potentially be extended to more-bit-controlled phase shifter applications.
A simple linearization technique using multiple gated common source transistors is proposed where gate width and gate drive (V-gs - V-th) Of each transistor are chosen to compensate for the nonlinear characteristics of the main transistor. To demonstrate the feasibility of this approach, a prototype double-gated RF amplifier using two MOSFETs is implemented and its RF characteristics are compared with those of a single one. The results show that, compared with a conventional single-gate transistor amplifier, the third order intermodulation (IMD3) is improved by 6 dB with similar gain, fundamental output power, and de power consumption. Because the auxiliary transistor is smaller than the main one and biased at subthreshold, adding this does not affect amplifier characteristics appreciably other than the nonlinearity. With further optimization using multiple gated transistors, much better nonlinear performance per power consumption would be expected.
In this letter, a novel photonic bandgap (PBG) structure is proposed for increasing the stopband of a low-pass filter without the increasing circuit size for applications in microstrip circuits. The proposed structure is connected in two parallel periodic structures which have a different center frequency of the stopband. The wide stopband is achieved by two periodic structures of two different stopbands. We also show the performance improvement of microstrip patch antenna by etching of the proposed structure in ground plane.
This letter deals with the problem of parasitic capacitance extraction in deep suhmicron layouts having general geometries. The presented extraction method is based on the statistical floating random walk algorithm. It employs a suitable spherical Green's function that, in a charge free region, relates the electrical field in the sphere center to the surface electrical potential
A method is presented to measure the dielectric properties of a thin film over a broad microwave frequency range. The parallel-plate transmission line geometry offers both the advantages of pronounced sensitivity to thin-film properties and exact computation of the value of the dielectric constant and the loss tangent. With multiline thru-reflect-line calibration techniques, the dielectric constant and loss tangent are determined to an accuracy better than 4% at 10 GHz
A novel method for realizing coupling between two orthogonal HEM/sub 11/ resonant modes in dielectric ring resonators is described. The coupling is obtained by means of a metallic strip located on the inner or on the outer boundary of the dielectric ring; a strong coupling is obtained, even with a small width of the strip, in particular when the strip is on the inner boundary. The dual-mode resonator is then suitable for filtering applications, with normalized bandwidth requirements exceeding 1% (as in base station units for mobile communications), allowing a relevant reduction of the overall volume, at the expense of a small reduction of the unloaded Q. The novel coupling mechanism and the Q degradation produced have been studied both numerically (by using finite elements simulations) and experimentally (measurements from a prototype two-resonators filter are reported).
This letter presents a physics-based improvement on the previous multilayer microstrip design equations that are found valid only for up to two layers. A three-layer example shows that the improvement leads to an excellent agreement between analytical calculations and moment method solutions. The improved equations are useful for designing any multilayer microstrip lines
Phase noise in a four-element array of oscillating antennas is analyzed for a loop configuration and a unilateral coupling topology. It is demonstrated that this structure, basically designed for circular polarization (CP) applications, also yields a 75% reduction of the near-carrier phase noise compared to a single oscillator. Experimental validation is made at 4 GHz. For this structure, deviation of the coupling phase from its nominal value has no influence on the phase noise performance.
In many microwave applications, an accurate knowledge of the complex permittivity properties of materials is usually required. A new procedure for the accurate determination of these properties is presented, based on an optimization algorithm that makes use of measured scattering parameters and simulated results of a cylindrical rod of dielectric material passing completely through a rectangular waveguide. The simulation tool employed consists of a very accurate hybrid iterative method. Results for the permittivity properties of ethanol (high-loss liquid material) are presented and validated with results from the literature.
Standard semiconductor fabrication processes have been used to form waveguide components for the submillimeter wavelength;range. A 585 GHz fundamentally pumped Schottky mixer with record performance demonstrates this technology. It consists of an etched silicon horn, a diced waveguide, and a lithographically formed microstrip channel for the diode circuit. The block dimensions are precisely controlled and extremely sharp. The measured mixer noise temperature is 1200K (DSB), which is equivalent to the best result obtained with standard metal machining.
A new integrated W-band frequency source MMIC is presented which consists of a 94 GHz voltage-controlled oscillator (VCO) with large tuning range and a phase comparator, forming a subharmonic injection-locked phase-locked loop (ILPLL). The ILPLL combines conventional injection-locking with an additional phase control loop to improve the locking range of the oscillator significantly. The 4th subharmonic frequency is used as the reference signal. The locking range was increased from 80 MHz without ILPLL to 4.5 GHz with ILPLL by closing the loop with an external DC amplifier. A phase noise of -83 dBc/Hz at 100 kHz offset was achieved. Pseudomorphic GaAs HEMT's and a coplanar circuit topology were used to allow integration into complex single-chip subsystems and flip-chip packaging
Monolithic Ka-band phase shifter circuit that employs voltage tunable BaSrTiO/sub 3/ (BST) parallel plate capacitors is presented here. The circuit is capable of continuous 0/spl deg/-157/spl deg/ phase shift at 30 GHz with an insertion loss of only 5.8 dB and return loss better than 12 dB. In addition to promising loss performance (27.1/spl deg//dB) at 30 GHz, the circuit reported here has several advantages over previously reported BST phase shifters such as moderate control voltages (20 V), room temperature operation, and compatibility with monolithic fabrication techniques.
Dielectric honeycombs are cellular materials often used in applications that require structural and electromagnetic characteristics, e.g., in LO (low observable) and radome components, A re-entrant (or auxetic) honeycomb is a cellular material with structural properties that are superior to those of a conventional honeycomb. By employing the finite-difference time-domain (FDTD) technique with periodic boundary conditions, the electromagnetic properties of re-entrant honeycombs are determined and compared to those of a conventional honeycomb. Re-entrant honeycombs are shown to have substantially superior electromagnetic properties. Measured permittivity data are used to substantiate the conclusions based on predicted FDTD data. The use of re-entrant honeycombs, rather than conventional honeycombs, in LO and radome applications can yield improved structural and electromagnetic performance.
A split field perfectly matched layer (PML) medium is introduced for the three-dimensional (3-D) alternating direction implicit (ADI) formulation of the finite-difference time-domain (FDTD) method. It is demonstrated that the ADI-FDTD method remains unconditionally stable with the inclusion of the PML. The effectiveness of the absorbing medium as a function of the time step is also demonstrated.
