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EP-4315496-B1 - HYBRID TYPE FILTER SOLUTION

EP4315496B1EP 4315496 B1EP4315496 B1EP 4315496B1EP-4315496-B1

Inventors

  • JIAN, CHUNYUN
  • ZHOU, MI
  • WANG, Zhen Hong
  • WANG, RICHARD
  • LINDELL, SVEN PATRIK
  • JANSSON, ANDERS

Dates

Publication Date
20260506
Application Date
20220310

Claims (10)

  1. An electromagnetic structure, comprising: an air cavity resonator (12) having a resonator post (14), and at least a first side wall, the first side wall of the air cavity resonator (12) having a first window (45a) parallel to a center axis of the resonator post; a first ceramic waveguide, CWG, resonator (10a) having an opening in a side wall of the first CWG resonator (10a), the opening being parallel to and at least partially aligned with the first window (45a) of the air cavity resonator (12) to couple energy between the air cavity resonator (12) and the first CWG resonator (10a); and a first bridge (46) having a length that extends from the resonator post (14) through the first window (45a) of the air cavity resonator (12) into an interior region of the first CWG resonator (10a), wherein the air cavity resonator (12) has a second side wall having a second window (45b) and the structure further comprises: a second CWG resonator (10b) having a second opening in a side wall of the second CWG resonator (10b), the second opening being parallel to and at least partially aligned with the second window (45b) of the air cavity resonator (12) to couple energy between the air cavity resonator (12) and the second CWG resonator (10b).
  2. The structure of Claim 1, wherein the first bridge (46) includes an electric conductor that makes contact with an edge of the first window (45a) of the air cavity resonator (12).
  3. The structure of any of Claims 1 and 2, wherein the first CWG resonator (10a) is configured to support a transverse electric, TE, mode with a magnetic field aligned with a magnetic field supported by the air cavity resonator (12).
  4. The structure of any of Claims 1 to 3, further comprising a second bridge (46) having a length that extends from the resonator post (14) through the second window (45b) of the air cavity resonator (12) into an interior region of the second CWG resonator (10b).
  5. The structure of any of Claims 1 to 4, wherein the first window (45a) of the air cavity resonator (12) is orthogonal to the second window (45b) of the air cavity resonator (12).
  6. The structure of any of Claims 1 to 5, wherein the first window (45a) of the air cavity resonator (12) is at a first height above a bottom wall of the air cavity resonator (12) and the second window (45b) of the air cavity resonator (12) is at a second height above a bottom wall of the air cavity resonator (12), the second height being different from the first height.
  7. The structure of any of Claims 1 to 6, wherein the first CWG resonator (10a) and the second CWG resonator (10b) are rectangular with parallel broad walls and parallel narrow walls, the parallel narrow walls being parallel to the center axis of the resonator post (14).
  8. The structure of any of Claims 1 to 7, wherein the first window (45a) of the air cavity resonator (12) is at a first height above a bottom wall of the air cavity resonator (12), the first height being selected to obtain a specified minimum coupling bandwidth between the air cavity resonator (12) and the first CWG resonator (10a).
  9. The structure of any of Claims 1 to 8, wherein the second window (45b) of the air cavity resonator (12) is at a second height above the bottom wall of the air cavity resonator (12), the second height being selected to reduce coupling of energy between the first and second CWG resonators (10a, 10b) to below a specified maximum allowable coupling.
  10. The structure of any of Claims 1 to 9, wherein the first window (45a) has a thickness forming a middle region between an interior region of the air cavity resonator (12) and an interior region of the first CWG resonator (10a), the middle region having a material with a relative permittivity greater than one.

Description

FIELD The present disclosure relates to wireless communications, and in particular, to hybrid filter solutions. BACKGROUND The Third Generation Partnership Project (3GPP) has developed and is developing standards for Fourth Generation (4G) (also referred to as Long Term Evolution (LTE)) and Fifth Generation (5G) (also referred to as New Radio (NR)) wireless communication systems. Such systems provide, among other features, broadband communication between network nodes, such as base stations, and mobile wireless devices (WD), as well as communication between network nodes and between WDs. Sixth Generation (6G) wireless communication systems are also under development. All of these standards, as well as other radio access technologies (RATs), contemplate transmission and reception in multiple frequency bands. Radio frequency (RF) transceivers at a radio base station may employ filters to filter signals to be transmitted by a radio transmitter of the transceiver as well as to filter signals that are received by a radio receiver of the transceiver. In particular, air cavity filters have high Q, where a high Q indicates that the air cavity filter has high frequency selectivity and energy storage capability. However, air cavity filters are large, heavy and expensive. In contrast to air cavity filters, ceramic wave guide filters (CWGF) are smaller, weigh less and are less expensive. However, ceramic wave guide filters have a lower Q than air cavity filters. According to one proposal, an air cavity filter is employed for transmission and a CWGF is employed for reception. However, a problem remains how to efficiently combine these filters for frequency division duplex (FDD) applications, where transmission is at one frequency and reception is at another frequency. The air cavity filter is much different in design and operation than the CWGF. In particular, the air cavity filter and the CWGF are different in size, materials, and location of manufacture. In one attempt to combine these two types of filters, a printed circuit board (PCB) has transmission lines that connect to the CWGF. The PCB is mounted close to the air cavity filter and connected to the air cavity filter by a cable. The two filters are ideally matched at the antenna port by adjusting the length of the cable according to a T-junction matching principle. Problems with this approach include additional loss due at least in part to difficulty in selecting the best length of cable to match the PCB to the air cavity filter. More particularly, the T-junction matching approach cannot provide matching for all ports of a dual band duplexer structure. CN 112 563 713 A discloses a dielectric resonator and a radio frequency filter. The dielectric resonator comprises a metal cavity and a dielectric body. An annular step is arranged in the metal cavity. The dielectric body is disposed within the metal cavity and includes a top surface, a bottom surface opposite the top surface, and a side surface between the top surface and the bottom surface. The peripheral portion of the bottom surface of the dielectric body is assembled on the top surface of the annular step. US 2019/280358 A1 discloses a filter and a communications device. The filter includes a metal cavity, a metal resonant cavity, and a metal cover covering the metal cavity and the metal resonant cavity. A dielectric waveguide is disposed in the metal cavity, and the dielectric waveguide is electrically connected to the metal cavity. Resonant rod is disposed in the metal resonant cavity. A coupling structure is disposed between the metal cavity and a metal resonant cavity that is neighboring to the metal cavity, the coupling structure includes a communication area between the metal cavity and the metal resonant cavity and a dielectric body that protrudes into the communication area, the dielectric body is connected to the dielectric waveguide, and the coupling structure is coupled to a resonant rod in the metal resonant cavity. US 2015/061793 A1 discloses a filtering apparatus including a passband of a first-level unit which is formed by at least three coaxial filters covers a passband of a second-level unit which is formed by at least three dielectric filters, and a bandwidth of the first-level unit is twice the bandwidth of the second-level unit. SUMMARY Some example advantageously provide hybrid structures, filters and duplexers. Accordingly, some example provide combinations of air cavity resonators or filters with ceramic wave guide resonators or filters. Some combinations disclosed herein contribute no additional loss, the loss being only that of each filter in the combination. Further, some combinations disclosed herein are compact. Single band, dual band and multiband configurations are disclosed herein. Some example are duplexers and multiplexers that provide high performance with less weight and complexity than known solutions. According to one aspect, as claimed with claim 1, an electromagnetic stru