No. 2 (2005)
Published:
2005-06-30
ARTICLES FROM THIS ISSUE
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Ultra-wideband radar targets discrimination based on discrete E-pulse synthesis
Abstract
A frequency domain approach to the E-pulse radar target discrimination technique is introduced. This approach allows the interpretation of E-pulse phenomenon via the E-pulse spectrum. The discrete E-pulse and its relation to continuous E-pulse are shown. The addition of extra zeroes to E-pulse structure has been suggested and its influence on the increasing of discrimination accuracy has been proved. The results of discrimination scheme digital simulation by using the characteristic E-pulse parameters for known targets are presented.
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Ultra-wideband 3D image processing for improving landmine detection with GPR
Abstract
This paper describes a new landmine detection algorithm starting from high resolution 3D ground penetrating radar (GPR) images. The algorithm consists of two procedures, object detection and object classification; both strongly depend on the properties of 3D GPR images. The algorithm has been tested on data measured with an ultrawideband (UWB) video impulse radar (VIR) system developed by the International Research Centre for Telecommunications and Radar (IRCTR). It was found that the algorithm is able to detect all landmines (including difficult to detect M14 mines) and classifies almost all landmines correctly with a large reduction in the number of false alarms caused by clutter. It turns out that for clutter removal it is most effective to eliminate detected objects with a small height.
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Analysis of errors in on-wafer measurements due to multimode propagation in CB-CPW
Abstract
We study for the first time errors in on-wafer scattering parameter measurements caused by the parasitic microstrip-like mode propagation in conductor-backed coplanar waveguide (CB-CPW). We determine upper bound for these errors for typical CPW devices such as a matched load, an open circuit, and a transmission line section. To this end, we develop an electromagnetic-simulations-based multimode three-port model for the transition between an air-coplanar probe and the CB-CPW. Subsequently, we apply this model to examine errors in the device S parameters de-embedded from measurements affected by the parasitic MSL mode. Our analysis demonstrates that the multimode propagation in CB-CPW may significantly deteriorate the S-parameters measured on wafer.
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A 100 W ISM 2.45 GHz-band power test system
Abstract
This paper describes development of solid-state microwave power test system (MPTS) operating over 2.3 to 2.6 GHz with the output power level of 100 W for industrial applications in material processing, and for designing of microwave power industrial equipment. The MPTS unit consists of four major parts: PLL synthesizer, high power solid-state amplifier, detector probes for return losses and leakage measurement and microcontroller. The MPTS system is able to operate in either single fixed-frequency regime, or in swept mode with self-tuning for minimum reflection of a heated load.
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A broadband multistate interferometer for impedance measurement
Abstract
We present a new four-state interferometer for measuring vectorial reflection coefficient from 50 to 1800 MHz. The interferometer is composed of a four-state phase shifter, a double-directional coupler and a spectrum analyzer with an in-built tracking generator. We describe a design of the interferometer and methods developed for its calibration and de-embedding the measurements. Experimental data verify good accuracy of the impedance measurement.
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Absorption of EM energy by human body in the vicinity of the GSM base station antenna
Abstract
A hybrid method is proposed for specific absorption rate analysis in a human body located in the near field of typical GSM base-station panel antenna. The method combines FDTD technique with analytical description of the near field of isolated antenna. The approximate results are found to be in excellent agreement with the results obtained by using the traditional FDTD. The most important advantage of proposed approach is minimization of computer memory requirements and
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Characterization of an aperture-stacked patch antenna for ultra-wideband wearable radio systems
Abstract
This paper presents, for the first time, the time-domain characteristics of an aperture-stacked patch antenna (ASPA) for ultra-wideband (UWB) wearable devices. The methodology of antennas characterization for UWB radio systems is also outlined. The antenna operates within the 3–6 GHz frequency band. Time- and frequency-domain characteristics of this antenna are presented in transmission mode (Tx), receiving mode (Rx) and for 2-antenna (Tx-Rx) system. The pulse driving the antenna has duration of 0.65 ns. In the Tx mode, pulses radiated in different directions of the H-plane have very similar shapes. Fidelity factors are as high as 91.6–99.9%. For 2-antenna system, pulses received in normal and end-fire-like directions have the fidelity of 69.5%. As it was found, antenna does not behave “reciprocal” comparing Tx and Rx modes. For normal propagation direction, radiated pulse is the 2nd derivative of the input waveform, but in the Rx mode, received pulse is the 1st derivative of the incident plane wave. This antenna can be used for transmission of short-pulses, even 0.65–1 ns in duration. It is also small (patch planar dimensions 32/19 mm) and compact. Microstrip configuration allows further integration of active devices on the same board. Taking into account above results we can say that ASPA is a good candidate for UWB non-invasive wireless body area network (WBAN) applications.
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Spatial power combiner using a planar active transmitarray of stacked patches
Abstract
An X-band spatial power combiner, which uses a planar transmitarray (TXA) of orthogonally polarized stacked microstrip patches integrated with input and output ports of transistor amplifiers is described. In order to obtain an increased operational bandwidth, the unit cell of the combiner with various stacked patch (SP) configurations is investigated. The configuration showing the smallest insertion losses is chosen for developing a TXA. The constructed spatial combiner includes a 4×4 cell TXA placed between two hard horn antennas. Its performance is assessed experimentally in terms of amplification gain and combining efficiency.
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Application of optical dispersion techniques in phased array antenna beam steering
Abstract
The paper presents an opto-electronic system for antenna beam control and results of model system measurements.
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A lightweight planar antenna element with optimized feed for use onboard spacecraft
Abstract
This paper is a report on low gain antennas (LGAs) manufactured with bonded lightweight materials. These antennas can sustain large temperature variations and are capable of functioning in modern miniature spacecraft, mainly in the telemetry, command and ranging (TC&R) links. When made of cheaper materials, the proposed circularly polarized antenna can be widely used in the base stations of short-range wireless systems. The recommended operating frequencies are between 1 and 8 GHz. One major technical consideration is obtaining the required high quality of circular polarization with as low space demands as possible. A lightweight 90◦ polarizer, printed on a dielectric membrane and operating over a broad bandwidth, is proposed for the antenna feed. Owing to the bandwidth advantage of the polarizer and the use of carefully designed aperture coupled feed, the electrical characteristics maintain good properties over a wide frequency range (15%).
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Applying the radiated emission to the specific emitter identification
Abstract
During the last years we have observed fast development of the electronic devices and electronic warfare systems (EW). One of the most principal functions of the ESM/ELINT system is gathering basic information from the entire electromagnetic spectrum and its analysis. Simultaneously, utilization of some tools of artificial intelligence (AI) during the process of emitter identification is very important too. A significant role is played by measurement and signature intelligence (MASINT) based on non-intentional emission (calls-radiated emission). This emission is a source of knowledge about an analysed emitter due to its incidental “chemical”, “spectral” traces and non-communication emitter’s char- acteristics. The process of specific emitter identification (SEI) based on extraction of distinctive radiated emission features is presented by the authors. Specially important is utilization of a database (DB) in the process of identifying a detectable radar emission.
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Broadside coupled stripline with double-side UC-PBG structure
Abstract
A stripline waveguide with double-side UC-PBG pattern is considered. To verify usefulness of the stripline structure with UC-PBG a 3 dB coupler has been designed and fabricated. Reduction of the coupler size (due to slow wave effect) has been predicted and observed. Numerical and experimental investigation confirmed enhanced backward coupling phenomena.
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All-optical intensity noise suppression for solid-state and semiconductor lasers
Abstract
This paper will report on a new all-optical technique of relative intensity noise (RIN) suppression for solidstate and semiconductor lasers. The new scheme we have used is based on an unbalanced Mach-Zehnder interferometer (UMZI), which is able to cancel the intensity noise enhancement at relaxation resonance. Although the relaxation oscillations frequency and the level of the corresponding noise maximum are extremely different concerning solid-state microchip lasers and semiconductor laser diodes, the proposed passive noise suppression is well suited for both types of laser sources used in telecommunication. The UMZ fiber interferometer solution for solid-state lasers demonstrated hereunder was generalized and deployed in case of semiconductor lasers as well.
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Mesh-free approach to Helmholtz equation based on radial basis functions
Abstract
Recently, a radial basis functions (RBFs) method, which was originally proposed for interpolation problems, has been developed and applied to solve partial differential equations and eigenproblems. Properties of that method (meshfree algorithm) allows one to use it in many areas, including electromagnetics. In this paper the mesh-free RBF method for solving Helmholtz equation was applied and a new adaptive algorithm for defining the set of interpolation centers was proposed. Using the proposed approach the cutoff wavelengths and the field distribution in cylindrical waveguides of arbitrary cross-section were calculated with a high accuracy.
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FDTD analysis of magnetized plasma using an equivalent lumped circuit
Abstract
The paper describes a new approach to electromagnetic analysis of magnetized plasma using finite difference time domain (FDTD) method. An equivalent lumped circuit describing an FDTD cell filled with plasma is developed and applied in the analysis. Such a method is proved more effective than previously reported methods. The new approach is verified on a canonical example of known analytical solution.
