A novel ultra-wideband (UWB) monocycle pulse generator with good performance is designed and demonstrated in this paper. It contains a power supply circuit, a pulse drive circuit, a unique pulse forming circuit, and a novel monopolar-to-monocycle pulse transition circuit. The drive circuit employs wideband bipolar junction transistors (BJTs) and linear power amplifier transistor to produce a high amplitude drive pulse, and the pulse forming circuit uses the transition characteristics of step recovery diode (SRD) effectively to produce a negative narrow pulse. At last, the monocycle pulse forming circuit utilizes a novel inductanceLshort-circuited stub to generate the monocycle pulse directly. Measurement results show that the waveform of the generated monocycle pulses is over 76 V in peak-to-peak amplitude and 3.2 ns in pulse full-width. These characteristics of the monocycle pulse are advantageous for obtaining long detection range and high resolution, when it is applied to ultra-wideband radar applications.
In this paper, we present a novel development of compact micropower ultrawideband (UWB) radar by integrating ultrashort balanced transmitter, sampling receiver, and antennas into a single package. The developed transmitter produces a pair of Gaussian pulses with 1 MHz of PRF, 400 ps of duration, and 8.3 V for peak-to-peak amplitude. The receiver down-converts microwave signals with a conversion gain of 3 dB over a 4.5-GHz bandwidth. The integrated UWB micropower radar system allows for the short-range detection with high range resolution and accuracy, thus enhance effectively the capability of target detection and classification. The high performances of such radar system for detecting objects are demonstrated through the realfield tests of various target scenes.Index Terms-Micropower impulse radar (MIR), UWB transmitter/receiver, UWB antenna, pulse generation, sample and hold circuit, nondestructive test.
A balanced pulse generator with high voltage amplitude and pulse width in the picoseconds region is described. It can operate well at the pulse repetition frequency (PRF) up to 500 kHz. The proposed generator contains four NPN silicon power transistors operating in avalanche mode and a pair of pulse shaping circuits which effectively utilise the transition characteristics of a step recovery diode. Measurement results are presented, which show the output of the generator are balanced pulses with peak values of ±46 V at 100 kHz PRF and approximately 330 ps full-width at half-maximum in width.
In high-frequency (HF) hybrid sky-surface wave radar, the first-order sea clutter broadening is severe under the action of ionospheric phase disturbance and bistatic angles. In this paper, a cascaded method is described to suppress the spread sea clutter. Firstly, the radar configuration and sea clutter broadening model are introduced based on the newly developed integrated HF sky-surface wave experimental system. In the cascaded processing method, a new ionospheric decontamination method based on general parameterized time-frequency (GPTF) analysis is proposed to estimate or correct the ionospheric phase distortion with large amplitude. Then, the forward-backward linear prediction (FBLP) algorithm is used to suppress the spread sea clutter caused by bistatic angle. Simulation results show that such ionospheric decontamination method based on GPTF is helpful for the large-amplitude ionospheric contamination when the target masking effect happens even after ionospheric phase decontamination. Finally, the proposed method is examined by the measured data. Experimental results indicate that the proposed method can well suppress the broadening sea clutter for HF hybrid sky-surface wave radars.
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