The paper presents the concept of using devices creating active interference characterized by a relatively low cost of implementation and that can provide, despite the low output power, an effect comparable to that obtained using expensive high power devices. Due to the fact that modern radars have many mechanisms that increase their tolerance to interference, including active ones, in this paper was proposed use for this purpose synchronized sources of interference, generating signals in specific frequency bands, corresponding to the frequency of the device being interrupted. Taking into account the above and remembering the limitations of currently known and used solutions (e.g. noise sources or digitally controlled), the article focuses on the concept of creating dedicated spatial interference using miniature microwave oscillators, synchronized by received signal from the device being interrupted.
Noise radars use random or pseudo-random signals to illuminate a target and coherent detection techniques in order to process received noise signals. In the range of microwave frequencies the simple analogue systems of the correlative detector may be used. It helps to overcome the fact that the real digital implementation of the autocorrelation function for these frequencies is very difficult. A correlator receiver is a typical element of the noise radar. The important issue is that coherent reception needs delay lines of constant or variable parameters to be applied in the receiving systems. To address this issue the paper comprises comparison of available technologies of microwave analogue delay lines. The advantages and disadvantages of presented solutions are presented. The paper comprises: the types of basic delay unit technologies, tunable and controlled-delay lines.