Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
  • H01P1/00—Auxiliary devices
  • H01P1/20—Frequency-selective devices, e.g. filters
  • H01P1/207—Hollow waveguide filters
  • H01P1/208—Cascaded cavities; Cascaded resonators inside a hollow waveguide structure
  • H01P1/2084—Cascaded cavities; Cascaded resonators inside a hollow waveguide structure with dielectric resonators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
  • H01P11/00—Apparatus or processes specially adapted for manufacturing waveguides or resonators, lines, or other devices of the waveguide type
  • H01P11/007—Manufacturing frequency-selective devices

Definitions

• the invention relates to waveguide filters.
• waveguide filter In electrical and communications engineering, by waveguide filter is meant any electronic filter that is based on electromagnetic waveguides. Waveguide filters are a basic component of electronic engineering designs and have numerous applications such as the selection of signals and limitation of noise. State-of-the-art waveguide filters are mostly employed in the radio and especially microwave spectrum due to their convenient size and low loss. Examples of known designs are given in JARRY, Pierre, et al. Advanced design techniques and realizations of microwave and RF filters. Hoboken, New Jersey: John Wiley, 2008. ISBN 0470183101 .
• PIM passive intermodulation
• EP 2656435 A (KATHREIN WERKE KG [DE]) 30.10.2013 proposes a high-frequency filter in coaxial design which allows a simple option for tuning resonators contained in the high-frequency filter.
• the invention aims to provide an improved waveguide filter.
• contamination of the aluminum used as raw material - such as by ferrite, nickel, steel or other ferromagnetic material - causes the casing to exhibit hysteresis when exposed to reversing magnetic fields, thus resulting in undesired passive intermodulation. Avoiding this intermodulation imposes a high degree of purity on the raw material employed, which in turn increases the unit cost of a filter manufactured from such material.
• the invention provides for a highly accurate filter ideally suited for measuring and testing purposes.
• the proposed filter may also be used in the mass market, where demand for wireless broadband has risend due to technological innovations such as third-generation (3G) and fourth-generation (4G) mobile services as well as the rapid expansion of wireless Internet services.
• 3G third-generation
• 4G fourth-generation
• a bandpass according to the invention enables broadcast licensees to tap the full potential of their allocated portion of the radio frequency (RF) spectrum, bidding for which requires staggering investments in many countries.
• RF radio frequency
• a transparent housing material enables the inventive use of laser ablation for tuning the filter while preserving the imperviousness of the casing.
• this fundamental modification allows the design of an airproof device that is fully sealed against intrusion by dust or liquids and thus protected from corrosion.
• Such apparatus operates reliably in harsh usage environments and under circumstances such as strong vibrations, extreme temperatures, and wet or dusty atmosphere, all of which are customary operating conditions for base stations in the context of mobile telephony, wireless computer networking, and other wireless communications.
• the inward-facing and outward-facing conductor of each port may be galvanically isolated by means of inductive or capacitive coupling.
• the invention also allows for a considerable reduction in unit cost. Specifically, the substitution of aluminum by an amorphous solid potentially renders performance of the filter independent from the purity of the starting material.
• a filter encased in glass proves extremely durable under most conditions, erodes very slowly, and withstands the action of water.
• the particle density of undesirable atoms and molecules inside the filter housing may be reduced by casting or molding the casing in a vacuum chamber such that the vacuum prevails in the resulting cavity. This way, its inside may be plated by means of vacuum deposition, thus yielding a plating of higher quality and more uniform thickness than would typically be achieved under atmospheric pressure.
• a noble metal for the conductive internal plating that is required to confine the electromagnetic field.
• silver is particularly preferred for its high electrical conductivity. Due to its malleability, ductility, and resistance to corrosion or other chemical reactions, a gold coating may optionally be superimposed. Resistance to chemical attack, excellent high-temperature characteristics, and stable electrical properties are also found in a surface layer of a platinum-group metal such as palladium, the latter being particularly preferred for its low density and melting point.
• a bandpass is manufactured from a set of coaxially aligned ceramic resonators. In a vacuum chamber, these are cast into a glass casing together with at least two pairs of inward-facing and outward-facing conductors designated as input and output ports. The cast is configured such that the resonators protrude into the cavity defined by their casing.
• each resonator is trimmed by laser ablation from outside the casing while measuring resonant frequency. This tuning process may be continued arbitrarily until the filter exhibits its designated frequency profile.
• a predetermined amount of silver is vaporized within the evacuated cavity and deposits on its inner surface as an internal plating.
• This silver base layer may optionally be replaced or superimposed by a layer of gold or palladium, effectively rendering the cavity impermeable to electromagnetic waves.
• the invention may be applied, inter alia, throughout the telephone networks, satellite communications, and television broadcasting industries.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Control Of Motors That Do Not Use Commutators (AREA)

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Cited By (2)

Citations (6)

• 2017
  • 2017-03-21 EP EP17161989.3A patent/EP3379642A1/fr not_active Withdrawn

Patent Citations (6)

Non-Patent Citations (2)

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