A low-loss 10 GHz range surface acoustic wave (SAW) filter is investigated. It is fabricated on 128° Y-X LiNbO₃ using electron beam direct writing and a lift-off process (aluminium electrode width = 95 nm, thickness = 30 nm). Experimental results of the ladder type SAW filter show low loss characteristics. A minimum insertion loss of 3.4 dB in the 10 GHz range is obtained.

A new single-phase unidirectional transducer utilising the difference between excitation and reflection positions caused by the floating electrodes of open and short metal strips inserted into the interdigital transducer within a half wavelength is described.

In the letter we describe and demonstrate a completely new application of SAW filters in present-day communication systems to realise a kind of transmit-receive switch (TRS). The TRS using the SAW filter works well up to expectations, replacing the required two bandpass filters and an antenna directional coupler. To do this the undesired reverse propagation sidelobe (higher) of a group-type unidirectional transducer (GUDT) has been used to advantage. The theoretical and experimental results are found to be in one-to-one correspondence.

A SAW filter (using GUDTs for excitation and detection) has been described, requiring no external discrete components for the matching and the phase shifting networks. Using this design the filter can be fabricated on a single chip of substrate using the integrated-circuit fabrication procedures. The theoretical analysis has been done using the crossfield equivalent-circuit model of the filter and the results are in good correspondence with the experimental results.