The unidirectional interdigital transducer topology features when designing SAW filters are considered. As well there are considered physical properties of various piezo‑crystals with different types of cut that allow to realize unidirectional operation of interdigital transducer. There are analyzed the conditions when the »natural» directivity of interdigital transducer becomes possible, topological variety of such transducers are considered. Various types of topology for transducers with a constant aperture are presented. Influence of the form, topology and dimensions of electrodes on characteristics of devices with directional interdigital transducers is analyzed. Influence of substrates technological parameters and interdigital transducers elements (electrodes material and thickness, substrate crystals types and cuts) on the value of attenuation and level of false signals is considered. Articles of functional electronics and SAW piezoelectric filters are used in various radio systems. Creation of passive wireless monitoring systems with use of SAW devices is considered as a separate direction of research.