287 results about "Electrical length" patented technology

The broadband low-profile dual-polarization omnidirectional antenna comprises a horizontal polarization radiator, a metal coupling patch, a vertical polarization radiator and a metal floor which are sequentially arranged from top to bottom, the horizontal polarization radiator comprises a dielectric substrate, and a horizontal polarization radiation patch and a feed network which are printed on the upper surface and the lower surface of the dielectric substrate; the metal coupling patch comprises a metal disc and a metal circular ring nested on the circumference of the metal disc; the horizontal polarization radiation patch is connected with the metal disc through a first short-circuit line, and the metal ring and the horizontal polarization radiation patch are connected with the metal floor through four second short-circuit lines and four third short-circuit lines respectively. Through short-circuit connection between the horizontal polarization radiation patch and the metal disc and between the metal circular ring and the horizontal polarization radiation patch and the metal floor, coupling between the horizontal polarization radiation body and the vertical polarization radiation body is achieved, the electrical length of the antenna is further prolonged, the bandwidth of the antenna can be effectively widened, and the profile of the antenna can be effectively reduced.

The invention discloses a terahertz wave band circularly polarized antenna based on sequential rotation feeding, and belongs to the field of radio frequency front-end devices. The circularly polarized antenna is composed of four microstrip patches, chamfers located on a radiation patch, a microstrip line, a microstrip line feed port, a sequential rotation feed network, a dielectric substrate, a metal ground backboard and a microstrip line matching structure. A 90-degree phase difference is generated by strictly designing the electrical length from each port to the feed network to realize circular polarization performance, right-handed circularly polarized waves are radiated, the radiation gain is 10.47 dB, the 3dB axial ratio bandwidth is greater than 8GHZ, the 3dB axial ratio range exceeds 90 degrees, and the complete half-power beam width is covered. The antenna adopts the microstrip line for feeding, the loss of the microstrip line is small, the microwave transmission characteristic is good, and the antenna radiation efficiency is high. The antenna adopts a single-layer board design, has no complex feed network, and is simple in structure and convenient to manufacture.

The invention relates to an antenna structure, a control method thereof, a control device and electronic equipment, the antenna structure comprises a radiator, two ends of the radiator are a first free end and a second free end respectively, the radiator is provided with a plurality of spaced feeding points and a plurality of spaced grounding points, and the feeding points are spaced from the grounding points; the radiator can move relative to the feed source and the floor, so that the feed source can be switched and connected to a target feed point, the floor can be switched and connected to a target grounding point, the target feed point is one of the plurality of feed points, and the target grounding point is one of the plurality of grounding points. Through the movement of the radiator relative to the feed source and the floor, the feed source can be switched and connected to the target feed point, and the floor can be switched and connected to the target grounding point, so that the electrical length of the radiator is changed, switching of multi-band communication can be carried out under the conditions of not additionally adding a tuner and not occupying the space of the whole machine; the frequency of the antenna is reconfigurable, and the working requirements of the antenna in different frequency bands are met.

The invention provides an electronic device. A floor of the electronic device comprises a first edge and a second edge which are connected in a bent mode. The first radiating body, the second radiating body and the floor are arranged at intervals, and orthographic projections of a first feeding point of the first radiating body and a second feeding point of the second radiating body on the floor are located in a current weak point area of characteristic current of the floor; the first feed source is electrically connected to the first feed point and the second feed point, the phase difference of excitation signals fed into the first feed point and the second feed point by the first feed source is 180 degrees, and the first radiator and the second radiator jointly excite the floor to generate excitation current flowing in the extension direction of the first edge under the action of the first feed source. And the wireless signal of the target frequency band is supported. Therefore, the first radiating body and the second radiating body are mainly used as feed structures and do not have harsh electrical length limitation, and the two radiating bodies can realize miniaturization design and enable the first antenna to have a relatively wide bandwidth.

The invention relates to the technical field of antennas, and further relates to a wide-beam multi-vibrator planar antenna supporting Tiantong Beidou frequency bands, which comprises a multi-vibrator radiation array element layer, a coplanar feed-amplitude shaping network, a stepped impedance matching section, a low-loss double-layer dielectric laminated layer and a metal reflecting plate, the outermost side of the multi-oscillator radiation array element layer is a PCB lamination layer; the coplanar feed-amplitude shaping network comprises a radiation patch, and different current amplitudes are provided for all oscillators through phase shift sections with different electric lengths so as to ensure that the half-power beam width can still reach 90 degrees or above under the condition of the shortest Beidou wavelength; the stepped impedance matching section is a pi-shaped converter formed by connecting three microstrip lines with different widths in series; and the low-loss double-layer dielectric laminated layer is used for solving the minimum distance between the metal reflecting plate and the PCB laminated layer according to the theoretical minimum gain. The antenna has the advantages of compact structure, stable gain and wide beam width.

A high-frequency component test device including a test key and a test module is provided. The test key includes a front-level key and a back-level key which are arranged symmetrically and have the same electrical length and characteristic impedance. The test module is used to measure an S parameter of the front-level key and the back-level key connected directly and an S parameter of a structure where a device under test (DUT) is added between the front-level key and the back-level key. The test module performs S parameter calculation in the frequency domain and converts the S parameter into an ABCD parameter matrix, and then obtains an ABCD parameter of a de-embedded DUT using a matrix root-opening operation and an inverse matrix operation.

The invention provides terminal equipment. The terminal equipment comprises a metal floor, a radiation branch knot and a feed source, the radiation branch knot is adjacent to and parallel to the preset edge of the metal floor, the projection of the radiation branch knot on the preset edge of the metal floor is located in the preset edge, and the radiation branch knot comprises at least one connecting part connected with the preset edge of the metal floor; the feed source is electrically connected with the radiation branch knot and is used for exciting the radiation branch knot to generate excitation current conducted along a first direction, so that the preset edge of the metal floor generates floor current, and the direction of the floor current of a first area corresponding to the radiation branch knot in the preset edge of the metal floor is a second direction; the direction of floor current in a second area in the preset edge of the metal floor is a first direction, the second area is adjacent to the first area, and the second direction is opposite to the first direction; the radiation branch comprises a main branch whose electrical length is 1 / 2 of the wavelength corresponding to the preset frequency band. Due to the current distribution, the directivity coefficient after far-field radiation electric field vector superposition is reduced, and the omni-directivity of the antenna is improved.

According to an embodiment, a plasma processing system includes a plasma chamber, an RF source, a matching circuit, a balun, and a resonating antenna. The resonating antenna includes a first and a second spiral resonant antenna (SRA), each having an electrical length corresponding to a quarter of a wavelength of a frequency of a forward RF wave generated by the RF source. The first end of the first SRA is coupled to a first balanced terminal of the balun and the second end of the first SRA is open circuit. The first end of the second SRA is coupled to a second balanced terminal of the balun and the second end of the second SRA is open circuit. The first and the second SRA are arranged in a symmetrically nested configuration having a same center point.

The invention provides an antenna assembly and electronic equipment. A radiation patch comprises a first grounding point, a feeding point and a second grounding point which are sequentially arranged along a first direction; the signal source is used for exciting the radiation patch to form a target resonance mode supporting a Bluetooth frequency band, the target resonance mode at least forms a 1 / 2 wavelength mode supporting the Bluetooth frequency band in a second direction, and the electrical length between the first grounding point and the side edge of the radiation patch in the first direction is smaller than the electrical length between the first grounding point and the side edge of the radiation patch in the second direction; the electrical length between the second grounding point and the side edge of the radiation patch in the first direction is smaller than the electrical length between the second grounding point and the side edge of the radiation patch in the second direction, and the peripheral side edge of the radiation patch is used for forming a clockwise or anticlockwise annular magnetic current between the peripheral side edge of the radiation patch and the reference floor in a target resonance mode. According to the invention, the stability of Bluetooth communication is improved.

A high frequency amplifier includes an asymmetrical Doherty amplifier having a carrier amplifier, a peak amplifier, a branch circuit, and a phase adjusting circuit, a driver amplifier, and a base member mounting a first circuit board mounting the driver amplifier, the carrier amplifier, and the peak amplifier and a second circuit board mounting the circuits. The branch circuit divides a path of a RF signal into input paths of the peak and carrier amplifiers. The driver amplifier, the carrier amplifier, and the peak amplifier have rear surfaces in contact with the base member. The electrical length from the output terminal of the driver amplifier to the input terminal of the peak amplifier, when converted based on a phase of the signal, is from (2n+1)×π−π / 4 to (2n+1)×π+π / 4, where n is an integer greater than or equal to zero.

The invention relates to the technical field of electromagnetic fields and microwaves, and provides an ultra-wideband tight coupling metal dipole antenna array with a wave trapping characteristic, which comprises a tight coupling metal dipole array positioned at the lower part and a planar wave absorbing structure positioned at the upper part, the tight coupling metal dipole array comprises M * N metal dipole units, the planar wave absorbing structure comprises M * N planar wave absorbing units, and each metal dipole unit comprises a left gradual change type dipole arm, a right gradual change type dipole arm, a left coupling metal piece, a right coupling metal piece, a feed printed board, a planar metal floor and a feed coaxial line; the planar wave absorbing unit comprises a supporting dielectric sheet, a planar dielectric substrate and printed patch layers, and the printed patch layers are printed on the upper surface and the lower surface of the planar dielectric substrate. And the central frequency point and the bandwidth of the notch frequency band can be adjusted by changing the electrical length and the rotation angle of the patch in the printed patch layer.

Provided in the present application is a terminal device, which comprises a metal ground plane, a radiating element and a feed source. The radiating element is arranged adjacent to and in parallel with a predetermined side of the metal ground plane, and the projection thereof on the predetermined side of the metal ground plane is located within the predetermined side. The radiating element comprises at least one connection portion connected to the predetermined side of the metal ground plane. The feed source is electrically connected to the radiating element and is used for exciting the radiating element to generate an excitation current conducted in a first direction, so that the predetermined side of the metal ground plane generates a ground plane current, wherein the direction of the ground plane current in a first region in the predetermined side of the metal ground plane corresponding to the radiating element is a second direction, and the direction of the ground plane current in a second region in the predetermined side of the metal ground plane is the first direction, the second region being adjacent to the first region, and the second direction being opposite to the first direction. The radiating element comprises a main element of which the electrical length is 1 / 2 of the wavelength corresponding to a preset frequency band. Such a current distribution reduces the directivity coefficient after vector superposition of far-field radiation electric fields, thereby improving the omnidirectionality of antennas.

The invention provides a three-dimensional frequency selector based on slow-wave loading slot lines, which comprises a plurality of slow-wave loading slot line units arranged periodically, and is characterized in that the slow-wave loading slot line units adjacent to each other along an x axis are separated by air layers to form periodic gaps in the x-axis direction; the adjacent slow wave loading slot line units along the y axis are directly connected; and the slow wave loading slot line unit comprises a slot line along the z-axis direction and a T-shaped metal patch loaded in a slot line gap. According to the invention, through x-y plane two-dimensional periodic arrangement and z-direction slot line gap extension, a three-dimensional structure is formed, and incident wave frequency selection is realized; after the T-shaped metal patch is loaded on the slot line, the equivalent electrical length is increased, and the phase velocity is reduced, so that the structure realizes the target space filtering characteristic under the condition of compact size.

The invention provides wrist-worn equipment. The wrist-worn equipment comprises a shell, a first pair of ear body parts, a first connecting part and a first antenna radiator, the first pair of ear body parts is arranged on the periphery of the shell and used for being connected with a wrist strap in a matched mode, and the first pair of ear body parts comprises a first ear body part and a second ear body part which are spaced from each other; the first connecting part is connected between the first ear body part and the second ear body part; the first antenna radiator is at least partially arranged on the first connecting part, the first antenna radiator is used for supporting communication of the Sub 1G frequency band, and the frequency range of the Sub 1G frequency band is 100 MHz to 1 GHz. Therefore, the influence of electronic components such as a mainboard in the wristwatch on the radiation efficiency of the first antenna radiator can be reduced, and due to the fact that the electrical length of the first antenna radiator supporting communication in the frequency band of 100 MHz to 1 GHz is long, the first antenna radiator can be arranged more conveniently due to the existence of the first connecting part.

According to an embodiment, a plasma processing system is proposed. The plasma processing system includes a plasma chamber; an RF source configured to generate a forward RF wave; an impedance matching circuit coupled to the RF source, the impedance matching circuit configured to provide matching for the RF source; a balun having unbalanced terminals coupled to the impedance matching circuit; and a resonant antenna configured to generate plasma within the plasma chamber, the resonant antenna being a spiral resonant antenna with an electrical length corresponding to a half-wavelength of a frequency of the forward RF wave, the resonant antenna comprising: a first tap along the spiral resonant antenna coupled to a first balanced terminal of the balun and a second tap along the spiral resonant antenna coupled to a second balanced terminal of the balun.

An antenna assembly, an electronic device main body, an electronic device, a storage medium and a control method of the electronic device, the antenna assembly comprises a circuit board, a main radiator, a parasitic radiator and a switching circuit, the main radiator is connected with a feed circuit of the circuit board, and the parasitic radiator is connected with the switching circuit. And the switching circuit is used for enabling the main radiator to feed the parasitic radiator under the conduction condition, and the switching circuit is used for enabling the main radiator not to feed the parasitic radiator under the turn-off condition. The parasitic radiator is controlled by the switching circuit, and the switching circuit can enable the main radiator to feed the parasitic radiator, so that the electrical length of the antenna assembly can be increased, and the antenna efficiency of the antenna assembly can be improved. In some application scenarios, if the parasitic radiator participates in radiation, the antenna performance is deteriorated, and the parasitic radiator can be controlled not to participate in radiation of wireless signals through the switching circuit, so that the antenna assembly can maintain better antenna performance in various application scenarios.

This application provides an antenna system and an electronic device, relating to the field of electronic device technology, enabling the antenna system on the electronic device to simultaneously consider both directivity and hand grip performance in landscape mode. The antenna system includes a first antenna, the radiator of which includes a first stub and a second stub; the first stub is disposed on a first side of the electronic device, the second stub is disposed on a second side of the electronic device, a first feed point is disposed at the connection between the first stub and the second stub, a first ground point is located on the portion of the radiator between the first feed point and the first end, and the electrical length of this portion of the radiator is 1 / 2 wavelength to 1 wavelength; a second ground point is located on the portion of the radiator between the first feed point and the second end, and the electrical length of this portion of the radiator is 1 / 8 wavelength to 1 / 2 wavelength. The antenna system provided by this application is used for signal transmission and reception.

A Doherty amplifier according to the present disclosure comprises a main amplifier, an auxiliary amplifier, a distribution circuit that distributes signals to the main amplifier and the auxiliary amplifier, and a phase compensation circuit. The main amplifier has a first input matching circuit and a plurality of main amplification stages. The auxiliary amplifier has a second input matching circuit and a plurality of auxiliary amplification stages. The distribution circuit has a first line connected to the first input matching circuit and a second line connected to the second input matching circuit. The electrical length of the first line is such that the input impedance of the first line is higher than the characteristic impedance of the first line and the imaginary component is less than 10% of the real component when a small signal is input. The electrical length of the second line is such that the input impedance of the second line is higher than the characteristic impedance of the second line and the imaginary component is less than 10% of the real component when a small signal is input. The phase compensation circuit is provided in an inter-stage matching circuit of the plurality of main amplification stages or the plurality of auxiliary amplification stages.

The present invention discloses a reconfigurable frequency MEMS standing wave meter based on a multi-port annular junction and a preparation method thereof, which is mainly composed of an annular directional coupler, a MEMS thermoelectric microwave power sensor and a MEMS variable capacitor. Two thermoelectric MEMS microwave power sensors located at the coupling port and the isolation port of the annular directional coupler respectively measure the output microwave power at the coupling port and the isolation port, thereby obtaining the magnitude of the incident microwave power and the reflected microwave power, and thus obtaining the magnitude of the standing wave ratio; six identical MEMS variable capacitors are equidistantly placed on the annular directional coupler, and different driving voltages are applied to the driving electrodes to change the height of the MEMS double-ended fixed beam, thereby changing the electrical length between the ports of the annular directional coupler, and realizing continuous tuning of the working frequency of the microwave standing wave meter. The present invention has the characteristics of miniaturization and tunability, is compatible with silicon-based CMOS technology, and is easy to integrate.

The invention discloses a center temperature detector and a combined cooking utensil with the center temperature detector. The invention relates to a center temperature detector (28) for a combination cooking appliance (10). The center temperature detector (28) comprises a measuring portion (32) and a handle portion (30). Furthermore, a contact tube (50) is provided, in which the cable (36) is guided. The cable (36) has an unsheathed region (88) in the handle part (30), in which unsheathed region (88) the contact tube (50) forms a contact point (90) together with the cable (36), the contact point (90) having a distance d1 to the handle-side end (52), which distance d1 corresponds to an electrical length of the microwave radiation in the handle part (30), the electrical length is shorter than or equal to a quarter of the wavelength of the microwave radiation used in the combination cooking appliance (10). The invention also relates to a combination cooking appliance (10) comprising a central temperature detector (28).

The application discloses a terahertz metasurface reflection unit based on a MEMS switchable delay line, and belongs to the field of radio frequency front-end devices.The unit adopts a sandwich structure of upper and lower glass substrates and a middle bonded metal surface, and a metal radiation patch, a phase delay line and a MEMS switch are integrated on the upper surface.The core is to control the on-off state of the phase delay line through the MEMS switch: when the switch is turned off, the unit is in a reference electrical length;when the switch is turned on, the current path is lengthened, so that the reflection phase lags by about 180 degrees, thereby realizing 1-bit phase coding.The design ingeniously combines the MEMS switch and the delay line, has the advantages of low driving voltage, low reflection loss and high phase control precision in the terahertz frequency band, and provides a feasible hardware solution for the practical application of a reconfigurable intelligent surface in a terahertz communication system.

The invention discloses a quasi-true time delay broadband beam forming network with Chebyshev amplitude distribution. The quasi-true time delay broadband beam forming network comprises a 3 * 4 beam forming network, a 4 * 4 true time delay network, an input port, an output port and the like. The 3 * 4 beam forming network comprises first to tenth parallel double-line couplers, first to seventh open-short circuit stub loading transmission lines and first to fourth 50-ohm transmission lines; the 4 * 4 real time delay network comprises first to eleventh real time delay circuits and first to fourth connecting lines. Broadband Chebyshev amplitude output is obtained by setting different coupling coefficients of the first to tenth parallel double-line couplers. In-band flat phase difference output is obtained by setting phase shift values of the first to fourth 50-ohm transmission lines, phase shift values of the first to seventh open-short circuit stub loading transmission lines and impedance values and electrical lengths of the open-short circuit stubs; through controlling the first to eleventh true time delay circuits, the phase slope between the output ports has a frequency-dependent characteristic, and after the antenna is connected, a consistent beam direction in a broadband range is obtained.

The invention relates to a breakable superconducting current device with variable power-on length and an adjusting method thereof, the device comprises a superconducting container, a current lead, a sealing ring, a conductive spring, a connector, a high-voltage connecting rod and a superconducting connecting line, the current lead passes through the superconducting container, and the current lead and the superconducting container are sealed through the sealing ring; the high-voltage connecting rod is connected or disconnected with the connector through the conductive spring; the current lead, the conductive spring and the connector are tightly connected in sequence to form an electrical path, compression of the conductive spring is achieved by pressing the current lead, and then the power-on length is adjusted. And the high-voltage connecting rod is connected with the superconducting connecting wire to form an electrical path. Compared with the prior art, the superconducting magnet only electrifies the current lead when needed, heat leakage caused by the current lead is reduced, the heat loss of the current lead is reduced, the use of a cooling medium is reduced, and the energy utilization efficiency of a system is improved.

An electronic device may have an antenna module with a triplet of antennas on a substrate. The triplet may include a first antenna with a radiating element formed from a patch on the substrate and second and third antennas having radiating elements formed from patches on that extend across a smaller lateral area than the patch in the first antenna. The patches in the second and third antennas may have extended electrical lengths formed from parasitic patches embedded within the substrate that are coupled to opposing edges of the patches by fences of conductive vias. The antenna module may include phased antenna arrays for conveying centimeter / millimeter wave signals. Signal conductors for the antennas may be distributed across multiple metallization layers of the substrate.

Provided in the present application is a terminal device, which comprises a metal ground plane, a radiating element and a feed source. The radiating element is arranged adjacent to and in parallel with a predetermined side of the metal ground plane, and the projection thereof on the predetermined side of the metal ground plane is located within the predetermined side. The radiating element comprises at least one connection portion connected to the predetermined side of the metal ground plane. The feed source is electrically connected to the radiating element and is used for exciting the radiating element to generate an excitation current conducted in a first direction, so that the predetermined side of the metal ground plane generates a ground plane current, wherein the direction of the ground plane current in a first region in the predetermined side of the metal ground plane corresponding to the radiating element is a second direction, and the direction of the ground plane current in a second region in the predetermined side of the metal ground plane is the first direction, the second region being adjacent to the first region, and the second direction being opposite to the first direction. The radiating element comprises a main element of which the electrical length is 1 / 2 of the wavelength corresponding to a preset frequency band. Such a current distribution reduces the directivity coefficient after vector superposition of far-field radiation electric fields, thereby improving the omnidirectionality of antennas.

Embodiments of the present application relate to an amplifying device and a transmitter. An amplifying device and a transmitter capable of compensating for a parasitic component of a circuit element without complicating a circuit structure are provided. The amplifying device includes a first amplifier that performs an amplifying operation on a signal; N-1 second amplifiers that perform an amplifying operation on the signal in sequence according to an amplitude of the signal in a case where the first amplifier performs the amplifying operation; N input networks connected to an input terminal that inputs the signal; N output networks connected between an output node of the first amplifier and a load connection node and connected between output nodes of the N-1 second amplifiers and the load connection node; and a first bias network that supplies a direct current bias voltage to at least one of the N output networks, an electrical length of the first bias network being less than 90 degrees.

The transmission path length detection device (3) is configured to include: a first electrostatic capacitance calculation unit (21) which observes the voltage change of the transmission path (2) in the communication network and calculates the overall electrostatic capacitance of the transmission path (2), i.e., the total electrostatic capacitance, based on the voltage change; a second electrostatic capacitance calculation unit (22) which measures the characteristic impedance of the transmission path (2) and calculates the electrostatic capacitance per unit length of the transmission path (2) based on the characteristic impedance; and an electrical length calculation unit (23) which divides the total electrostatic capacitance calculated by the first electrostatic capacitance calculation unit (21) by the electrostatic capacitance per unit length calculated by the second electrostatic capacitance calculation unit (22) to thereby calculate the electrical length of the transmission path (2).

The utility model discloses a microstrip patch antenna which comprises a dielectric substrate and a radiation patch. The radiation patch is arranged on the dielectric substrate, the radiation patch is E-shaped, the parallel edge of the E-shaped radiation patch is defined as a first sub-radiation patch, the vertical edge of the E-shaped radiation patch is defined as a second sub-radiation patch, and the length of the first sub-radiation patch is larger than or equal to 2.1 mm and smaller than or equal to 2.5 mm. The E-shaped structure enables the current to bypass between the first sub radiation patch and the second sub radiation patch, which is equivalent to increasing the electrical length of the radiation patch and reducing the resonant frequency of a fundamental mode, so that the low-frequency band bandwidth is broadened; the edges of the first sub-radiation patch and the second sub-radiation patch can generate strong electromagnetic field coupling to excite an additional parasitic resonance mode, so that the frequency band is further widened, and the bandwidth of the microstrip patch antenna is effectively widened. Wherein the first sub radiation patch of 2.1 mm to 2.5 mm enables the resonant frequency of the microstrip patch antenna to range from 43.7 Ghz to 55.1 Ghz, the relative bandwidth is 23%, and high bandwidth is achieved.

Embodiments of the present application provide a calibration device, a differential clamp, and related devices and systems. The calibration device includes a non-equivalent length reflection calibration piece for calibrating a scattering parameter of a differential signal obtained based on the differential clamp. The non-equivalent length reflection calibration piece includes a first line and a second line. An electrical length of the first line is not equivalent to an electrical length of the second line. A difference between a length of the first line and a length of the second line is within a preset range. The preset range is determined based on a bandwidth of the differential signal. Embodiments of the present application can accurately obtain the scattering parameter of the differential signal in the case of using the differential clamp.

Distribution element high-frequency (HF) filter, comprising: a ceramic substrate that has a grounding plate on a first surface of the substrate; a first resonator on a second surface of the substrate opposite the first surface, wherein the first resonator is electrically connected to a first input / output interface (I / O interface) near a first end of the substrate; a second resonator on the second surface of the substrate, wherein the second resonator is electrically connected to a second I / O interface near a second end of the substrate opposite the first end; one or more intermediate resonators on the second surface of the substrate, wherein the one or more intermediate resonators are located between the first and the second resonator, wherein each of the first, second and one or more intermediate resonators has an electrical length that nominally corresponds to half a wavelength of a center frequency of the filter, wherein each of the first, second and one or more intermediate resonators comprises a resonator section between first and second resonator end sections, which are electrically connected to the grounding plate by a conductive wall near a common side of the substrate, wherein each resonator at least partially surrounds a section of the surface of the substrate on which the resonator is located.