By interweaving the fingers of an interdigital transducer with an earthed meander line and supplying different voltages, in different phases, to the fingers, a variety of interesting performances may be achieved. Two unidirectional transducers and a diplexing transducer are described as examples of the technique. In order to achieve the performances that theory indicates, a number of technical problems need to be overcome. These problems are pointed out and approaches to their solution are suggested.