## 1 Introduction  
Modern hardware systems performing digital signal processing can easily reach high complexity, since they typically consist of many specialized devices. In turns, the majority of these devices are assembled from a variety of electronic components, in which electric currents and voltages play the primary role in the description of phenomena at the physical level. For instance, one of the typical issues solved in the electromagnetic compatibility framework [1] is the detection of potential sources of interference, which may affect the stable work of the entire device or even neighboring devices. A traditional and easy to understand model describing the property of components can be built as an electric circuit being assembled from lumped elements only or lumped elements properly combined with parts of transmission lines. The proper choice of an appropriate model is mainly based on two points. The first one is the primary role of the component, i.e., whether it is intended to be an antenna, microstrip line, connector, frequency selective filter, or the input port of an embedded integral circuit. The second point is determined by a certain relation between the spectrum width of the processed signals and the passband (or passbands) of the analyzed component. Thus, in the case of digital signal processing, where the spectrum is considered to be concentrated in a baseband with respect to the lowest resonant frequency range, the component's electric property can often be modelled as a simplified \(RC\) circuits [2]. However, if the resonance behavior cannot be neglected, a more accurate model, exhibiting weak resonant properties, may well be introduced by means of a generalized resonant circuit, either of parallel or serial type, with relatively low Q factor, typically not exceeding the value of 2. In an ultrawideband case, where the signal spectrum spreads over a frequency band covering several natural electromagnetic modes of the component, the appropriate model has to be reconsidered. The simple approach to enhancing the lump-element model consists in combining multiple resonant circuits [3]. However, this can be performed accurately only if the component possesses sharp resonances; otherwise, such a model will be nothing but an approximation technique, which can be developed further, to surrogate models [4]. An alternative approach proposes the extra inclusion of an idealized transmission line, while the lumped element remains the resonant circuit [5]. Models of this type showed high performance in cases where the natural resonances are rather smooth or the introduction of transmission line can be proved with geometric or physical reasoning [6]. Although the normal operating mode of signal processing devices suggests periodically processing structured signals with random information components [7], deterministic periodic signals will inevitably be present. Moreover, during the verification phase, a device can be switched to a special mode, where the processed signals are to be changed to satisfy predetermined sequences, forming patterns inheriting the true periodical structure. At first glance, the accurate analysis of power in the elements of low Q circuits does not seem to be difficult. However, this problem turns out to be challenging when it comes to the excitation by electric currents or voltages described by arbitrary periodic waveforms. Thus, in modern university level textbooks devoted to engineering circuit analysis, e.g., those authored by [PERSON] [8] or [PERSON] [9], the topic of power analysis in electric circuits is generally taught in an ambivalent manner. In the beginning, instantaneous power tends to be introduced as a time-varying function that is a product of the voltage across, and current through, an element or extracted one port within the analyzed circuit. Next, the average power evaluation is shown for a case in which the circuit is in a steady state mode caused by constant or periodical excitation by its sources.