A filter device includes a transmission line formed by an electrically conducting strip printed on a surface of an electrically insulating substrate, the conducting strip having two ends respectively forming the two sole input and output connection ports of the filter device, and a plurality of resonators, each resonator including an electrically conducting strip printed on the surface of the substrate. The conducting strip of each resonator has a first end coupled to the transmission line and at least one second end that is free or connected to a ground so as to create an effective fundamental resonant wavelength specific to each resonator. For each pair of neighboring resonators of the plurality of resonators, the distance between the first ends of the two neighboring resonators is less than one tenth of the smallest effective fundamental resonant wavelength of the plurality of resonators.

A microstrip capacitor structure includes a substrate having a first side and a second side opposite the first side wherein the first and second sides of the substrate are spaced apart in a vertical direction, first and second conductive microstrip transmission line segments on the first side of the substrate, a conductive ground plane on the second side of the substrate, first and second microstrip capacitor plates connected to respective ones of the first and second microstrip transmission line segments, wherein the first and second microstrip capacitor plates are separated by a dielectric gap, and a complementary resonator comprising a removed portion of the conductive ground plane that is aligned in the vertical direction with at least a portion of the dielectric gap. The first and second microstrip transmission line segments extend in a first direction of RF signal propagation and the complementary resonant structure comprises first and second complementary resonant structures spaced apart in a second direction that is perpendicular to the first direction, and a transverse portion that extends in the second direction and connects the first and second complementary resonant structures.

The present invention includes a method of creating electrical air gap low loss low cost RF mechanically and thermally stabilized interdigitated resonate filter in photo definable glass ceramic substrate. Where a ground plane may be used to adjacent to or below the RF filter in order to prevent parasitic electronic signals, RF signals, differential voltage build up and floating grounds from disrupting and degrading the performance of isolated electronic devices by the fabrication of electrical isolation and ground plane structures on a photo-definable glass substrate.

A resonant unit and a filter, where the resonant unit includes a dielectric substrate, a metal microstrip disposed on a plane of the dielectric substrate, where the metal microstrip is used as a signal input/output port, and a defected ground structure disposed on another plane opposite to the plane of the dielectric substrate, where the defected ground structure includes a ground loop and an interdigital structure located inside the ground loop, the interdigital structure includes multiple fingers, and the ground loop or at least one finger in the interdigital structure includes at least one embedded interdigital structure. Harmonic suppression capabilities of the resonant unit and the filter can be improved, and an area can be reduced.

Embodiments of the present invention disclose a microstrip multiplexer, including a feeder, multiple microstrip filters, and a signal processing network. The multiple microstrip filters are separately connected to the signal processing network, and the signal processing network is connected to the feeder. Output signals of the microstrip filters of the multiple microstrip filters are combined by using the signal processing network and then output by using the feeder and/or a signal input from the feeder is split by using the signal processing network and then output to the microstrip filters. In the embodiments of the present invention, a wideband multiplexer that combines multiple wide subband signals for using can be implemented, and each subband has good frequency band response.

A process-invariant RC circuit is formed by patterning a metal layer using the same mask pattern to form a metal layer resistor and a metal layer capacitor. The same mask pattern results in the metal layer resistor and the metal layer capacitor each having a plurality of longitudinally-extending fingers having the same width and separation.

A tunable RF filter circuit (AHF) is specified which enables good electrical properties, good tunability and simple driving despite low complexity. In this case, the filter circuit comprises a first and a second signal route (SW1, SW2) in a signal path (E, A). At least three resonant circuits (RK1, RK2, RK3) are arranged one after another in the second signal route and interconnect the second signal route with ground. The resonant circuits are electrically and/or magnetically coupled (K) and each comprise a tunable impedance element. The second signal route contains an impedance element (IMP).

A coaxial filter comprises a housing that surrounds a receiving space. The housing comprises a trough-shaped housing element with sidewalls and a front wall. The housing further comprises a further trough-shaped housing element, wherein the two trough-shaped housing elements are placed on top of one another, thus forming the receiving space; or a lid arrangement which, together with the trough-shaped housing element forms the receiving space. At least one resonator inner conductor arrangement comprises a connecting bridge, with which resonator inner conductors are conductingly connected.

A band elimination filter includes a plurality of parallel resonators, each including a piezoelectric substrate and an IDT electrode on a surface of the piezoelectric substrate. The IDT electrode includes a pair of comb-shaped electrodes opposing each other, and the IDT electrode includes electrode fingers, a pitch of the electrode fingers being different between an end portion of the IDT electrode in a propagation direction of an elastic wave and a central portion of the IDT electrode different from the end portion.

A filter apparatus includes a first conductive signal line configured to form a first radio frequency resonator; a second conductive signal line configured to form a second radio frequency resonator; a cross-coupling element comprising a first electrode arranged to couple capacitively to the first conductive signal line, a second electrode arranged to couple capacitively to the second conductive signal line, and an electrically conductive signal line coupling the first electrode to the second electrode. The cross-coupling element is bendable with respect to the first conductive signal line and the second conductive signal line to adjust the capacitive coupling.