SURFACE ACOUSTIC WAVE ELEMENT, SURFACE ACOUSTIC WAVE CONVOLVER USING THE ELEMENT AND COMMUNICATION SYSTEM USING THE CONVOLVER

摘要

PURPOSE: To excite surface acoustic waves in one direction with a single phase structure and to improve energy conversion efficiency by arranging bus bars for which plural electrode fingers for inputting the signals of the same phase are bundled and connected on the right and left of the electrode finger, cancelling one direction and strengthening the other direction. ;CONSTITUTION: In the three-phase type UDT of a comb-line electrode, the electrode fingers 121... are respectively connected to the bus bars 111 and 115 for connecting grounded electrodes and the bus bars 113 and 114 and 112 and 116 for high frequency signals provided with the phase difference of 60° at a center frequency and arranged on the right and left. The phases of electric fields among the electrode fingers 127, 128... are shifted by 120° each and thus, since the excited surface acoustic waves advancing in a right or left direction are strengthened or cancelled with each other between the electrodes, only the surface acoustic waves advancing in the right direction are excited. Thus, the three-phase UDT is realized with a single layer structure without the need of a gap cross electrode, loss is made small and highly efficient communication is performed.;COPYRIGHT: (C)1995,JPO