Saw filter with a coupled saw impedance element

A low loss filter comprising:

• a filter means having a passband;
• a piezoelectric substrate;
• and
• a SAW impedance element supported by said piezoelectric substrate and electrically coupled in parallel to said filter means, wherein said SAW impedance element has a resonance frequency in a frequency region lower than the passband for the filter means, wherein the low loss filter is a SAW filter.

A radio telephone low loss filter comprising:

• a filter means having a passband;
• a piezoelectric substrate;
• and
• a SAW impedance element supported by said piezoelectric substrate and electrically coupled in series to said filter means, wherein said SAW impedance element has an anti-resonance frequency in a frequency region higher than the passband for the filter means, wherein the low loss filter is a SAW filter.

A low loss filter comprising:

• a filter means having a passband;
• a piezoelectric substrate;
• and
• a SAW impedance element supported by said piezoelectric substrate and electrically coupled in series to said filter means, wherein said SAW impedance element has an anti-resonance frequency in a frequency region higher than the passband for the filter means, wherein the series coupled SAW impedance element substantially satisfies the following condition:
• ##EQU19##

A low loss filter comprising:

• a filter means having a passband;
• a piezoelectric substrate;
• and
• a SAW impedance element supported by said piezoelectric substrate and electrically coupled in parallel to said filter means, wherein said SAW impedance element has a resonance frequency in a frequency region lower than the passband for the filter means, wherein the parallel coupled SAW impedance element substantially satisfies the following condition:
• ##EQU20##