Abstmct-This paper describes a processing technique for combining stepped-frequency waveforms efficiently t o obtain higher range resolution. Essentially this method involves the reconstruction of a wider portion of the target's reflectivity spectrum by combining the individual spectra of the transmitted narrowbandwidth pulses in the frequency domain. This paper describes the signal processing steps involved, and shows simulation results which validate and illustrate the method.Keyword-Stepped-frequency processing, synthetic range profile, SRP, target reflectivity spectrum.

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Abstract-Class-E amplifiers are a type of switching amplifier offering very high efficiency approaching 100% . In this paper, a topology and design methodology, which could be used for a transmission-line implementation of a class-E power amplifier, is presented. A simple transmission-line class-E load network is proposed that offers combined transformation of the load resistance down to a suitable level, as well as simultaneous suppression of harmonics in the load. The load network was developed and tested with the aid of a time-domain simulator (i.e., SPICE). A microstrip layout was designed and a first prototype was built operating at 1 GHz utilizing a field-effect transistor as the switching device. A drain efficiency of 72% was measured for our prototype after tuning, although better performance can be expected with an improved switching transistor and careful tuning of the load network.

A novel Frequency Domain, Stepped Frequency Processing(FD-SFP) technique to obtain high radar range resolution was developed by AJ Wilkinson in 1997. Range resolution is directly related to the measurement bandwidth of a radar system. The FD-SFP technique pieces together several sub portions of the target scene reflectivity spectrum to form a high resolution radar range return. This paper demonstrates the use of the FD-SFP algorithm on the CSIR X-Band experimental SAR system (RoofSAR). Some issues arising in practical implementation of the technique are discussed. Results of using the technique on radar data recorded by the RoofSAR are presented. It is concluded that the technique provides a viable optlon for generating SAR imagery with high range resolution and an acceptable level of ghosting artifacts.

A novel electrical resistance tomography (ERT) measurement system has been developed, which uses a switched bi-directional constant current source to produce the electric field in the measuring vessel. Potential difference measurements are made on both the positive and negative half cycles and subtracted, cancelling any DC components present at the measuring electrode solution interface. The resulting voltage is a function of conductivity distribution in the medium. This technique is considerably simpler than conventional systems involving the injection of sinusoidal current followed by synchronous or DSP based detection. Further, because the current pulse is DC, the differential measurements do not require demodulating and therefore the technique has the potential for high-speed operation. The current pulse technique is justified in terms of the electrochemistry occurring at the electrodes and electronic circuitry used.The Newton-Raphson (NR) algorithm was used for reconstruction. Experiments were performed on a model system of (a) non-conducting object(s) in a conducting liquid, and on liquid foams of varying bubble size. Visualizations showed that the system could resolve the position and size of the objects, and identify coarse foam regions.