a surface acoustic wave device configured to operate as a spectrum analyzer , and having an array of input transducers disposed on a substrate in such positions as to produce a focused beam of acoustic energy at a focal arc , each position on the arc being representative of an input signal frequency . output transducers produce electrical signals corresponding to the energy received at successive segments of the focal arc . the disclosed device includes various combinations of input transducer array improvements , some of which are to provide amplitude weighting of the input array , including aperture width weighting , capacitive weighting , resistive weighting , series - parallel weighting , and source withdrawal weighting . another improvement in input array configuration eliminates close or overlapping electrodes of opposite polarities and thereby reduces parasitic capacitance and acoustic radiation between electrode elements . the use of curved input transducer fingers improves operation of the transducers as point sources . other important improvements include the use of acoustic transducers before to transmit the focused output energy from the focal line to conventional output transducers , thereby improving frequency resolution , and the use of electromagnetic waveguides to transmit energy from output transducers located on the focal line .