REVERSIBLE TRANSDUCER WITH NATURAL DIRECTIVITY OF SURFACE ACOUSTIC WAVES (DESIGN VERSIONS) Russian patent published in 2000 - IPC

FIELD: radio electronics; intermediate- and carrier-frequency filters of radiophones, pagers, mobile communication systems, etc. SUBSTANCE: supplying electric signal to unidirectional transducer incorporating elementary sections of counter- phase exciting electrodes and reflecting electrode excites surface acoustic waves in piezoelectric substrate which propagate in forward and reverse directions. Substrate is made of single chip where mechanical and electromagnetic components of propagating surface acoustic wave are relatively shifted through Δϕ ≈ ±45^°, so as to ensure natural directivity of radiation. Width of first and second exciting electrodes in each elementary section b₁= λ/8 and b₃= 3λ/16, respectively and reflecting electrode width b₅= 3λ/16. Distance between adjacent edges of first and second exciting electrodes b₂= λ/8 and distance between adjacent edges of second exciting electrode and reflecting electrode b₄= λ/4, where λ is length of surface acoustic wave at midpoint. Width of exciting electrodes in second design version b₁= λ/8 and b₃= λ/4 and that of reflecting electrode b₅= λ/4 at gaps b₂= b₄= λ/8. Under mentioned conditions, center of excitation of surface acoustic waves is offset relative to their center of reflection through ±λ/8 which raises efficiency of surface acoustic wave conversion by 20% at the same time enhancing natural directivity of waves in reverse direction. EFFECT: reduced insertion loss of transducer and associated filter. 2 cl, 7 dwg