A method of constructing an RF filter comprises designing an RF filter that includes a plurality of resonant elements disposed, a plurality of non-resonant elements coupling the resonant elements together to form a stop band having a plurality of transmission zeroes corresponding to respective frequencies of the resonant elements, and a sub-band between the transmission zeroes. The non-resonant elements comprise a variable non-resonant element for selectively introducing a reflection zero within the stop band to create a pass band in the sub-band. The method further comprises changing the order in which the resonant elements are disposed along the signal transmission path to create a plurality of filter solutions, computing a performance parameter for each of the filter solutions, comparing the performance parameters to each other, selecting one of the filter solutions based on the comparison of the computed performance parameters, and constructing the RF filter using the selected filter solution.

A filter that can make a reflection delay of an initial stage coupling part correspond to a change in a passband due to a manufacturing error of a substrate or the like is realized. A filter according to an example embodiment includes: a substrate having a dielectric property; an initial stage coupling part formed on the substrate; and an interstage coupling part formed on the substrate. The initial stage coupling part is formed so that a reflection delay is decreased in accordance with an increase in a passband due to a manufacturing error of the substrate or the interstage coupling part, or so that the reflection delay is increased in accordance with a decrease in the passband.

A method of constructing an RF filter comprises designing an RF filter that includes a plurality of resonant elements disposed, a plurality of non-resonant elements coupling the resonant elements together to form a stop band having a plurality of transmission zeroes corresponding to respective frequencies of the resonant elements, and a sub-band between the transmission zeroes. The non-resonant elements comprise a variable non-resonant element for selectively introducing a reflection zero within the stop band to create a pass band in the sub-band. The method further comprises changing the order in which the resonant elements are disposed along the signal transmission path to create a plurality of filter solutions, computing a performance parameter for each of the filter solutions, comparing the performance parameters to each other, selecting one of the filter solutions based on the comparison of the computed performance parameters, and constructing the RF filter using the selected filter solution.

The invention relates to a switchable band-pass filter. In particular, the invention relates to a narrowband switchable band-pass filter over a broad frequency band with two filter elements (including microstripline technology, suitable for use as a cosite filter with a compact structure, which is particularly suitable for efficient mass production and robust in operation. The two filter elements in this context are coupled to one another, on the one hand via a switchable coupling device and, on the other hand, via a direct electromagnetic interaction.

A distributed electromagnetic (EM) wave filter includes: a cavity; upper and lower ground planes on top and bottom surfaces of the cavity, wherein the upper and lower ground planes are in electrical contact; a plurality of electromagnetically coupled resonators in said cavity between the upper and lower ground planes that define respective transmission lines, wherein the plurality of resonators are not connected to each other by a conductive connection; an input port coupled to a first one of the plurality of resonators to receive an EM wave; an output port coupled to a last one of the plurality of resonators to output a filtered EM wave; and a plurality of conductive structures between adjacent resonators, respectively and connected to one or more of the upper and lower ground planes.

A method of constructing an RF filter comprises designing an RF filter that includes a plurality of resonant elements disposed, a plurality of non-resonant elements coupling the resonant elements together to form a stop band having a plurality of transmission zeroes corresponding to respective frequencies of the resonant elements, and a sub-band between the transmission zeroes. The non-resonant elements comprise a variable non-resonant element for selectively introducing a reflection zero within the stop band to create a pass band in the sub-band. The method further comprises changing the order in which the resonant elements are disposed along the signal transmission path to create a plurality of filter solutions, computing a performance parameter for each of the filter solutions, comparing the performance parameters to each other, selecting one of the filter solutions based on the comparison of the computed performance parameters, and constructing the RF filter using the selected filter solution.

A method of constructing an RF filter comprises designing an RF filter that includes a plurality of resonant elements disposed, a plurality of non-resonant elements coupling the resonant elements together to form a stop band having a plurality of transmission zeroes corresponding to respective frequencies of the resonant elements, and a sub-band between the transmission zeroes. The non-resonant elements comprise a variable non-resonant element for selectively introducing a reflection zero within the stop band to create a pass band in the sub-band. The method further comprises changing the order in which the resonant elements are disposed along the signal transmission path to create a plurality of filter solutions, computing a performance parameter for each of the filter solutions, comparing the performance parameters to each other, selecting one of the filter solutions based on the comparison of the computed performance parameters, and constructing the RF filter using the selected filter solution.

Balun with tunable bandpass filter characteristic includes first, second and third coupling elements disposed on a substrate. The first and second coupling elements are arranged on the substrate relative to the third coupling element to couple two identical but out of phase signals to form a corresponding unbalanced signal in the third coupling element. A plurality of tunable resonator elements are distributed within an area of the substrate defined on one side by the first and second coupling elements and on an opposing side by the third coupling element. The tunable resonator elements are configured to selectively produce a bandpass filter response.

Embodiments of the present invention disclose a filter, including: a conductive box body, and an insulating substrate, a first conductor, and a second conductor that are arranged inside the conductive box body. The insulating substrate includes a first surface and a second surface. The first conductor is arranged on the first surface of the insulating substrate. A position on the second surface corresponding to the first conductor contacts with the conductive box body. The second conductor is arranged on the first surface or the second surface of the insulating substrate. The second conductor and the conductive box body form a coaxial resonant cavity together. Further, an end of the second conductor is coupled with the first conductor, and the other end of the second conductor is coupled with the conductive box body. The filter has advantages of a microstrip filter of simple manufacturing process and small volume.

A resonance device and a filter including the same are provided. The resonance device includes a case having a first ground surface and a second ground surface which are facing each other, and a first conductive layer located in the case, and the first conductive layer includes a main part grounded via the first ground surface, and a protruding part which has a width different from that of the main part and is located to be spaced apart from the second ground surface.