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In this paper, we propose a novel amplitude-comparison monopulse receiver architecture for ultra-wideband radars. This monopulse receiver consists of four ridged-horn antennas placed in a square-feed configuration, a comparator circuit that generates the monopulse sum and difference signals, cross-correlation receivers that detect the monopulse signals, and an amplitude-comparison monopulse processor that determines the target's angular position. The derived monopulse sum and difference signals are verified through measurements. The derived sum and difference patterns are compared with measured patterns, and they show good agreements--measured 3-dB beamwidth = 6.4[degrees](derived = 6[degrees]), measured unambiguous tracking range = [+ or -]5[degrees](derived = [+ or -]5[degrees]), and measured sum pattern sidelobe level = -6 dB (derived = -8 dB). Index Terms--Monopulse radar, radar receivers, radar tracking, time-domain analysis, ultra-wideband (UWB) radar.

A pulse-forming network (PFN) has been developed for ultra-wideband (UWB) communication systems. This PFN generates sub-nanosecond pulses at a pulse repetition frequency (PRF) of >500 MHz for high data-rate applications like wireless video streaming. To generate the pulses, the PFN performs two operations on an input data signal: it decreases the signal rise time, then it differentiates the signal. The differentiation circuit is a frequency-dependent negative-feedback system. The PFN is fabricated in SiGe BiCMOS with an active die size of less than 0.25 [mm.sup.2], and it requires 3.3-V 20-mA dc during operation. Measured performance is validated at 500-MHz PRF, achieving pulsewidth of 175 ps and pulse amplitude of 0.17 V. The PFN is also validated within a transmitter system that transmits Manchester coded pseudorandom bit sequence. Measured effective isotropic radiated power of the transmitter shows that the PFN output power is sufficient to meet the Federal Communications Commission's emission limits, thus eliminating the need of amplification before transmission. Index Terms--Analog integrated circuits (ICs), differentiating circuit, pulse generation, transmitter, ultra-wideband (UWB) communications.

The relative permittivity of materials is extracted using time domain radar pulse reflection measurements. The pulse reflected from an arbitrarily shaped dielectric object is compared with that reflected from its metallic equivalent to determine the object’s dielectric constant. The proposed method achieves accuracies of over 85% for permittivity and within 2 mm for material thickness estimations. Using the proposed technique, the complex relative permittivity for various objects is extracted over a frequency range from 3 to 10 GHz. This method has been applied to determine the permittivity of a ridge of sand and to dielectric imaging. [ABSTRACT FROM AUTHOR]