Dielectric duplexer with different capacitive coupling between antenna pad and transmitting and receiving sections

• US 6,052,040 A
• Filed: 03/02/1998
• Issued: 04/18/2000
• Est. Priority Date: 03/03/1997
• Status: Expired due to Fees

• Current Assignee: NGK Spark PLUG Company Limited
• Original Assignee: NGK Spark PLUG Company Limited
• Inventors: Hino, Seigo
• Primary Examiner(s): Ham, Seungsook
• Application Number:
  US09/033,160
• Time in Patent Office: 778 Days
• Field of Search: 333/132, 333/126, 333/129, 333/134, 333/202, 333/206, 333/207
• US Class Current: 333/134
• CPC Class Codes: H01P 1/2136 using comb or interdigital filters; using cascaded coaxial cavities H01P1/2131, H01P1/2135 take precedence

Abstract

A compact and highly effective dielectric duplexer comprises a dielectric ceramic block and a plurality of resonators arranged in a direction in the dielectric ceramic block, a half of the resonators constituting a transmitting section T, the remaining half of the resonators constituting a receiving section R, wherein an antenna terminal pad is capacitively coupled to the innermost resonator of the transmitting section T and to the innermost resonator of the receiving section R located adjacent to the innermost resonator to eliminate the use of a wave-dividing resonator, whereby the dielectric ceramic block can be dimensionally reduced in the direction along which resonators are arranged and hence it is adapted to down-sizing. Additionally, the coupling capacitance Ct of the antenna terminal pad and the transmitting section T is made greater than the coupling capacitance Cr of the antenna terminal pad and the receiving section R, whereby a return loss is reduced in both the transmitting section T and the receiving section R to improve the signal transmitting performance and the signal receiving performance of the dielectric duplexer.

Claims

1. A dielectric duplexer comprising:

a dielectric ceramic block;

a plurality of juxtaposed resonators provided in the dielectric ceramic block, which include through holes extended through the dielectric ceramic block sequentially along a direction and internal conductors covering the inner peripheral surfaces of the through holes, the resonators being divided into a group of resonators located near a lateral side of the dielectric ceramic block and operating as a transmitting section and another group of resonators located near the opposite lateral side of the dielectric ceramic block and operating as a receiving section;

an external conductor covering the outer peripheral surface of the dielectric ceramic block except the open-circuit end surface on which one end of each through hole is exposed;

a first input/output pad arranged on the dielectric ceramic block and electrically isolated from the external conductor but capacitively coupled to the outermost resonator of the transmitting section;

a second input/output pad arranged on the dielectric ceramic block and electrically isolated from the external conductor but capacitively coupled to the outermost resonator of the receiving section; and

an antenna terminal pad arranged only on a side surface of the dielectric ceramic block, electrically isolated from the external conductor, and capacitively coupled through the block to the innermost resonator of the transmitting section and the innermost resonator of the receiving section located adjacent to the innermost resonator of the transmitting section, respectively, the antenna terminal pad, the innermost resonator of the transmitting section and the innermost resonator of the receiving section being relatively positioned to each other, and the capacitive coupling between the antenna terminal pad and the innermost resonator of the transmitting section being of greater value than the capacitive coupling between the antenna terminal pad and the innermost resonator of the receiving section.

2. A dielectric duplexer according to claim 1, wherein the antenna terminal pad is arranged closer to the transmitting section than to the receiving section.

3. A dielectric duplexer according to claim 1, wherein the innermost resonator of the transmitting section is displaced from the remaining resonators of the transmitting section in a direction perpendicular to a line connecting the centers of the remaining resonators of the transmitting section toward the surface of the dielectric ceramic block where the antenna terminal pad is located.

4. A dielectric duplexer according to claim 1, wherein the antenna terminal pad includes an enlarged portion located closer to the transmitter section than to the receiving station.

5. A dielectric duplexer according to claim 1, wherein each of the resonators has a coupling member on the open-circuit end surface of the dielectric ceramic block, for coupling the adjacent resonators to each other.

6. A dielectric duplexer according to claim 5, wherein the coupling member of the innermost resonator of the transmitting section and the coupling member of the innermost resonator of the receiving section are separated by a distance which reduces coupling capacitance between them.

7. A dielectric duplexer according to claim 5, wherein the coupling member of the innermost resonator of the transmitting section is extended closer to the antenna terminal pad than the coupling member of the innermost resonator of the receiving section.