Sensing of stochastic waves with logarithmic periodic linear antenna arrays

Time-domain electromagnetic interference (EMI) measurement systems sample the broad-band EMI signal with GHz sampling rates and compute the EMI spectrum by digital signal processing. This yields not only a reduction of the measurement time by three to four orders of magnitude but also excellent broadband pulse transfer characteristics. In order to fully exploit the broadband performance of modern time-domain EMI measurement systems for measurements of radiated EMI, broadband antennas with excellent pulse transfer characteristics are required. In this work we investigate the broadband direction characteristics of logarithmic periodic linear antennas for electromagnetic interference sensing. We compute the directivity of linear logarithmic antenna arrays for stochastic plane waves by delay time synthesis for stochastic plane waves with Gaussian and rectangular spectra. For stationary signals the sensor beams can be formed on the basis of the autocorrelation functions of all pairs of sensor element signals. For sensing incident stationary stochastic signals, the correlation functions of the antenna elements only need to be measured pairwise.