Aspects of the disclosure are directed to a bandpass filter including a first, second, third and fourth resonators, wherein the second and third resonators are in parallel, wherein the first resonator includes a first and second terminals, wherein the second resonator includes a second resonator top terminal and a second resonator bottom terminal, wherein the third resonator includes a third resonator top terminal and a third resonator bottom terminal, wherein the fourth resonator includes a third terminal and a fourth terminal; wherein the first terminal is coupled to the second resonator top terminal, wherein the second terminal is coupled to the third resonator top terminal, wherein the third terminal is coupled to the third resonator bottom terminal, wherein the fourth terminal is coupled to the second resonator bottom terminal; a first inductor coupled to the first and third terminals; and a second inductor coupled to the second and fourth terminals.

A printed film RF micros trip bandpass filter includes a plurality of resonators disposed on a dielectric substrate, first and second input/output (I/O) interfaces connected to corresponding first and second resonators flanking one or more intermediate resonators. Opposite ends of the one or more intermediate resonators are connected to a ground plane on an opposite side of the substrate by corresponding conductors. The intermediate resonators have an electrical wavelength that is one-half a wavelength of a center frequency of the filter and the first and second resonators can have an electrical wavelength that is nominally one-half the wavelength of the bandpass filter center frequency.

A multiband resonator element which, on the one hand, compensates the components of an electromagnetic field radiated from its phase centre, located on the axis of symmetry of the resonator, to control the polarization purity of a radiating element. On the other hand, it enables the selection of the electromagnetic fields reflected and transmitted on a frequency- and multiband-selective surface. In this sense, this is an innovative element that enables the design of directive radiating elements and with an axial ratio for its circular polarization less than or equal to 1.5 dB for all the angles belonging to the hemisphere centred on broadside. Thus, it can be used in the design of reflectarrays, transmitarrays and any dichroic multiband surface, likewise on metamaterial surfaces.

A ceramic dielectric band-pass filter includes a ceramic base, a first input and output electrode, and a second input and output electrode. The ceramic base includes an open surface, a short-circuit surface, and an IO surface. The ceramic base includes first resonant cavities and second resonant cavities penetrating the ceramic base. The first resonant cavities are arranged between the second resonant cavities and are arranged along a length direction of the ceramic base. The first input and output electrode and the second input and output electrode are arranged on the IO surface and extend to the open surface. The first input and output electrode, the second input and output electrode, and the first resonant cavities are coupled to form a sixth-order band-pass filter. The first input and output electrode and the second input and output electrode are coupled with the second resonant cavities to form notch filters.

The present invention relates to a cavity filter. The cavity filter includes: an RF signal connecting portion spaced apart, by a predetermined distance, from an outer member having an electrode pad provided on a surface thereof; and a terminal portion configured to electrically connect the electrode pad of the outer member and the RF signal connecting portion so as to absorb assembly tolerance existing at the predetermined distance and to prevent disconnection of the electric flow between the electrode pad and the RF signal connecting portion, wherein the terminal portion is divided into a first side terminal contacted with the electrode pad and a second side terminal connected to the RF signal connecting portion, absorbs the assembly tolerance existing in a terminal insertion port, in which the terminal portion is provided, through an elastic member provided between the first side terminal and the second side terminal, and prevents disconnection of an electric flow, thereby preventing degradation in performance of an antenna device.