Abstract: The present invention is a preferred monoblock ceramic bandpass duplexer filter. The preferred filter has at least three I/O pads. One of the pads is coupled to an antenna, another is connected to a transmission circuit and the last pad is connected to a receive circuit. The filter is comprised of two sections: a transmission section and a receive section. The transmission and receive sections include resonators disposed on respective sides of the antenna pad. A first alternative signal path is disposed adjacent the ends of the transmission resonators. A second alternative signal path is disposed adjacent to the ends of the receive resonators. Each alternative signal path couples adjacent and non-adjacent resonators. A further feature of the filter of the present invention includes a shunt zero resonator for the transmission section. To the contrary, the present invention allows the elimination of a shunt zero resonator for the receive section of the filter.

Abstract: The present invention is a preferred monoblock ceramic bandpass duplexer filter. The preferred filter has at least three I/O pads. One of the pads is coupled to an antenna, another is connected to a transmission circuit and the last pad is connected to a receive circuit. The filter is comprised of two sections: a transmission section and a receive section. The transmission and receive sections include resonators disposed on respective sides of the antenna pad. A first alternative signal path is disposed adjacent the ends of the transmission resonators. A second alternative signal path is disposed adjacent to the ends of the receive resonators. Each alternative signal path couples adjacent and non-adjacent resonators. A further feature of the filter of the present invention includes a shunt zero resonator for the transmission section. To the contrary, the present invention allows the elimination of a shunt zero resonator for the receive section of the filter.

Abstract: A ceramic transverse-electromagnetic-mode filter having a resistive paste base and resistive paste layer and method of tuning same is provided. The ceramic filter includes a filter body (200) comprising a block of dielectric material and having top (202), bottom (204) and four side surfaces (206, 208, 210, 212) including vertical edges (214). The filter also has metallized through-holes providing transverse-electromagnetic-mode resonators (210). At least one vertical portion in proximity to the vertical edges (214) of the block on at least one of the side surfaces is unmetallized providing a resistive paste base (218). A resistive paste layer (219) of predetermined resistivity is deposited thereon. The resistive paste layer attenuates a set of parasitic spurious responses in the filter frequency response curve while simultaneously maintaining a desired transverse-electromagnetic-mode passband.

Abstract: A ceramic transverse-electromagnetic-mode filter having a waveguide cavity mode frequency shifting void and method of tuning same is provided. The ceramic filter includes a filter body (200) comprising a block of dielectric material and having top (202), bottom (204) and four side surfaces (206, 208, 210, 212) including vertical edges (214). The filter also has metallized through-holes providing transverse-electromagnetic-mode resonators (216). At least one vertical portion in proximity to the vertical edges (214) of the block on at least one of the side surfaces is unmetallized providing a waveguide cavity mode frequency shifting void (218). The waveguide cavity mode frequency shifting void (218) shifts a set of parasitic spurious responses in the filter frequency response curve to a lower frequency while simultaneously maintaining a desired transverse-electromagnetic-mode passband.

Abstract: A method of tuning a duplex filter (500). First, the center frequency of at least one filter of a duplex filter (10) is measured (502). Next, the difference between the measured center frequency and a desired center frequency is determined (504). And, third the duplex filter is tuned (506) by selectively removing a substantially planar layer of dielectric material for a top surface (14) of the filter (10), whereby the frequency characteristics are modified.

Abstract: A ceramic duplex filter is provided. The duplex filter (10) has a filter body (12) of a dielectric material, and has a top (14), bottom (16) and side surfaces (18, 20, 22, and 24) with through-holes extending from the top (14) to the bottom surface (16). Receptacles are positioned adjacent to the top surface (14) with a conductive material therein. The surfaces (16, 18, 20, 22 and 24) are substantially covered with a conductive material defining a metallized layer (25), with the exception that the top surface (14) is substantially unmetallized. The receptacles include a conductive layer of material to define a certain capacitance. And, coupling devices (94, 96 and 98) for coupling signals into and out of the duplex filter (10) are provided. Shunt, series and coupling capacitors are strategically positioned adjacent to the top surface (14), which help to facilitate tuning of the filter.