Maximum emission levels of photonically generated impulse radio waveforms under spectral constraints

Abstract

Since it has been first discovered in the analysis of the black-body radiation problem, the emission of spectrally constrained electromagnetic radiation is frequently encountered at different parts of the spectrum, ranging from microwave (MW) frequencies, up to the visible band of the spectrum. These spectral constraints tend to limit the radiated electromagnetic energy, its spectral density and/or the bandwidth occupied by this energy. In this work, analytical closed-form expressions are developed for the maximum emission levels of photonically generated impulse radio-ultrawide band (IR-UWB) waveforms. Both the energy spectral density (ESD) and the bandwidth constraints imposed on these waveforms are considered. The validity of using the derived expressions as upper bounds on the radiation efficiencies of IR-UWB waveforms in practical UWB systems is experimentally demonstrated. Although the conducted analysis is applied to the MW band, it has the advantage of being applicable to other impulse waveforms that occupy other parts of the electromagnetic spectrum, including the milli-meter wave band and the tera-Hertz band, under arbitrarily different ESD and bandwidth constraints.