Observed properties of an acoustic-surface-wave multistrip coupler

The properties of an acoustic-surface-wave multistrip coupler constructed on YZ LiNbO3 are reported. The device was made by standard photolithographic techniques and consisted of 100 separate aluminium strips at a repeat distance of 16 ¿m. Over a bandwidth of at least 30% centred at 86 MHz, the coupling factor was less than 1 dB with a directivity of approximately 30 dB. Some applications of the coupler are discussed; in particular, it is shown that the device may be used as a filter to discriminate between bulk and surface acoustic waves.