In the tradition of the previous three conferences, the proceedings of the 4th Ultra-Wideband Short-Pulse Electromagnetics Conference explores topics including pulse generation and detection; broadband electronic systems; antennas - theory, design, experiments and systems; pulse propagation; scattering theory; signal processing; and buried targets - detection and identification.In the tradition of the previous three conferences, the proceedings of the 4th Ultra-Wideband Short-Pulse Electromagnetics Conference explores topics including pulse generation and detection; broadband electronic systems; antennas - theory, design, experiments and systems; pulse propagation; scattering theory; signal processing; and buried targets - detection and identification.Generation of High-Power Subnanosecond Pulses.- Fundamental Physical Considerations for Ultrafast Spark Gap Switching.- Novel source of Powerful Subnanosecond Microwave Pulses Based on Superradiance.- Demonstration of Sub-Millimeter Radiation Generation from Static Field by a Superluminous Ionization front in Semiconductor Capacitor Array.- About Mechanism of Wideband Microwave Radiation at Explosion of Condensed High Explosives.- Calorimetric Spectrometer for Measuring Single Microwave Pulses in Relativistic Microwave Electronics Devices.- Universal Sensor Using Electro-Optic Sensing Principles.- Wave Equations and Transmission Formulas for the Output of a Receiving Antenna.- Energy Consideration in Space-Time Synthesis of Collimated Pulsed Apertures.- Intermediate Field of an Impulse-Radiating Antenna.- Aperture Efficiencies of Impulse Radiating Antennas.- Transient Gain of Antennas Related to the Traditional Continuous-Wave (CW) Definition of Gain.- Ultra-Wideband Sources and Antennas.- Multifunction Impulse Radiating Antennas: Theory and Experiment.- Antenna-Source Integrated Ultra-Wideband Electromagnetic Pulses Radiating Device.- Large Current Radiator for the Short Electromagnetic Pulses Radiation.- A lóÊ