Abstract: An antenna assembly includes a radiation plate, a first feed board, and a second feed board. The radiation plate includes a radiation patch and a plurality of slot members, and each slot member includes a fixing groove and a guide groove communicating with the fixing groove. The first feed board includes a first fixing member at an end facing the radiation patch. The second feed board includes a second fixing member at an end facing the radiation patch, and the second feed board is compatible with the first feed board through a plug-in connection. The fixing grooves of the plurality of slot members respectively match the first fixing member and the second fixing member to realize an in-line cooperation of the radiation plate, the first feed board, and the second feed board.

Abstract: Systems, methods, and circuitries are disclosed for providing a retrodirective array. One example retrodirective array includes a plurality of dual-polarized antenna elements configured to receive a pilot signal having a first polarization and phase conjugation circuitry. The phase conjugation circuitry includes, for each of the plurality of antenna elements, a mixer configured to mix the pilot signal with an LO signal to generate a phase conjugated signal and excitation circuitry configured to generate an excitation signal for the antenna element to transmit the phase conjugated signal with a second polarization that is different from the first polarization.

Abstract: A dual band antenna that allows the independent optimization of each frequency band by adjusting the sizes of the antenna elements. For example, an antenna may have two different drivers, one for the high-frequency and one for the low frequency. By using elements orthogonally connected to the low frequency driver, the low frequency driver can function as both a reflector to the high frequency drivers and the low frequency driver without affecting the antenna's performance in the high frequency. The antenna may also have parasitic elements. For example, parasitic directors parallel to the high frequency band driver can be configured to improve performance in the high frequency band. Pairs of additional parasitic directors can be orthogonally connected these directors. These pairs can be adjusted in size to improve performance in the low frequency band with minimal impact on performance in the high frequency band.

Abstract: An antenna and a base station including the antenna. The antenna includes a sub-array that includes first and second unit cells and a feed network. The first and second unit cells comprise first and second patches, respectively, having quadrilateral shapes. The feed network comprises a first transmission line terminating below first corners of the first and second patches, respectively; a second transmission line terminating below third corners of the first and second patches, respectively; a third transmission line terminating below a second corner of the first patch and a fourth corner of the second patch; and a fourth transmission line terminating below a fourth corner of the first patch and a second corner of the second patch. The first corners are opposite the third corners on the respective first and second patches and the second corners are opposite the fourth corners on the respective first and second patches.

Abstract: The disclosure applies to the field of antenna technology, which provides an antenna oscillator and an antenna. The antenna oscillator includes an antenna oscillator body, the antenna oscillator body has a rectangular planar plate-like structure. The first slit and the second slit have strip-shaped structures without branches and are configured on the antenna oscillator body. The first slit and the second slit extend in the direction of the long side of the rectangle and the antenna oscillator body is configured with a pore structure. It can receive and transmit electromagnetic wave signals of a larger bandwidth, expand the effective bandwidth of the antenna oscillator and obtain better signal intensity for each frequency within the effective bandwidth.

Abstract: A controlling method and a communication device are disclosed. The controlling method is applied to a communication device with a plurality of antennas. The controlling method includes the following operations: comparing a plurality of environmental parameters of the antennas in a comparison time interval to generate a determination result, wherein the determination result includes whether to switch the plurality of the antennas; adjusting the comparison time interval and a maintenance time interval according to the determination result; and transmitting or receiving wireless signals in the maintenance time interval. The controlling method and the communication device have the advantages of communication capability optimization and power saving.

Abstract: A streaming media player includes a printed circuit board, a video processor, a wireless communications processor, and a patch antenna. The patch antenna includes dielectric material, a conductive patch, and a first antenna feed in a first position with respect to the conductive patch. The patch antenna includes a second antenna feed in a second position with respect to the conductive patch. The first position is orthogonal to the second position. In an embodiment, the second position is rotationally offset from the first position by 90 degrees around an axis through a center of the conductive patch. The streaming media player includes a connector coupled to the video processor and configured to removably couple to a connection port on a display device.

Abstract: A waveguide antenna apparatus includes a lower laminate layer of non-radio-frequency (RF) material and a first layer of conductive material formed on a top surface of the lower laminate layer of non-RF material. A middle layer of non-RF material formed over the first layer of conductive material, the middle layer of non-RF material comprising a waveguide cavity formed through the middle layer of non-RF material, such that air forms a propagation medium for radiation in the waveguide cavity. An upper layer of non-RF material is formed over the middle layer of non-RF material, and a second layer of conductive material is formed on a top surface of the upper layer of non-RF material, the first and second layers of conductive material and the waveguide cavity being part of a waveguide antenna.

Abstract: An antenna includes a radiator, where the radiator includes three parts separated by a gap, an end of a second part proximate to a first part is a first end, and an end of the second part proximate to a third part is a second end, a medium-high frequency feeder, electrically coupled to the radiator at a first coupling point, a low frequency feeder electrically coupled to the radiator, a first ground cable electrically coupled to the radiator at a second coupling point, where an adjustable component for controlling conduction of the first ground cable is disposed on the first ground cable, a length from the second coupling point to an end that is in the first end and the second end and that is further from the first coupling point is a quarter of a wavelength corresponding to a resonance frequency.

Abstract: Examples disclosed herein relate to a multi-frequency electromagnetic feed line. The multi-frequency electromagnetic feed line includes a waveguide that has a plurality of slots arranged laterally along a length of the waveguide that corresponds to a first axis, in which the plurality of slots are configured to radiate electromagnetic signaling from an input end of the waveguide to a terminal end of the waveguide. The waveguide also has a plurality of vias arranged proximate to the terminal end of the waveguide in a predetermined angle relative to a second axis orthogonal to the first axis, in which the plurality of vias are configured to terminate the plurality of slots for different frequencies of an operating frequency band. A first slot of the plurality of slots that is arranged closest to the terminal end has varying distances to different vias. Other examples disclosed herein relate a method of fabricating a waveguide.

Abstract: The invention relates to an antenna. The antenna comprises a feed line having first and second ends on opposite sides of the feed line, wherein a transmission axis is defined as the axis extending between the first and second ends of the feed line. Further, the antenna comprises a plurality of antenna elements arranged along the feed line, protruding from the transmission axis. The antenna also comprises a first port at the first end of the feed line, wherein, at a first part of the antenna, the feed line, from the first port towards a reference point along the transmission axis, comprises antenna elements of gradually increasing length, configured to radiate in a first direction along the transmission axis from the reference point towards the first port during excitation in the first port.

Abstract: An antenna and a base station including the antenna. The antenna includes a sub-array that includes first and second unit cells and a feed network. The first and second unit cells comprise first and second patches, respectively, having quadrilateral shapes. The feed network comprises a first transmission line terminating below first corners of the first and second patches, respectively; a second transmission line terminating below third corners of the first and second patches, respectively; a third transmission line terminating below a second corner of the first patch and a fourth corner of the second patch; and a fourth transmission line terminating below a fourth corner of the first patch and a second corner of the second patch. The first corners are opposite the third corners on the respective first and second patches and the second corners are opposite the fourth corners on the respective first and second patches.

Abstract: A system and method provide simultaneous dual polarization operation using a linearly-polarized planar antenna and a polarizer spaced apart from the linearly-polarized planar antenna, the polarizer including a first polarization state having primarily one of left-hand circular polarization (LHCP) or right-hand circular polarization (RHCP), and a third polarization state having linear polarization from which a combination of both LHCP and RHCP is simultaneously derived. The polarizer is placed in the first polarization state to at least one of transmit or receive a signal having primarily one of LHCP or RHCP, and the polarizer is placed in the third polarization state to simultaneously transmit and/or receive two different signals, where a first signal of the two different signals has primarily LHCP and a second signal of the two different signals has primarily RHCP.

Abstract: The present disclosure provides an antenna system including an antenna assembly embedded in a grounding foundation plate. The antenna assembly includes a first printed circuit board, a second printed circuit board, a third printed circuit board, a first conductive layer, a feed sheet, a second conductive layer, a first radiation gap disposed in the second conductive layer, and a second radiation gap disposed in the second conductive layer. The antenna assembly further includes a feed point disposed at one end of the feed sheet for electrically connecting to an external circuit and transferring the power to the second conductive layer via the feed sheet, by which, the first radiation gap works at a first frequency band, and the second radiation gap works at a second frequency band. Both of the first and second frequency bands are included in 5G frequency bands.

Abstract: A radio frequency (RF) aperture includes an interface board. An array of electrically conductive tapered projections have bases disposed on a front side of the interface printed circuit board and extend away from the front side of the interface printed circuit board. RF circuitry is disposed at the back side of the interface board and is electrically connected with the electrically conductive tapered projections.

Abstract: A system and method provide simultaneous dual polarization operation using a linearly-polarized planar antenna and a polarizer spaced apart from the linearly-polarized planar antenna, the polarizer including a first polarization state having primarily one of left-hand circular polarization (LHCP) or right-hand circular polarization (RHCP), and a third polarization state having linear polarization from which a combination of both LHCP and RHCP is simultaneously derived. The polarizer is placed in the first polarization state to at least one of transmit or receive a signal having primarily one of LHCP or RHCP, and the polarizer is placed in the third polarization state to simultaneously transmit and/or receive two different signals, where a first signal of the two different signals has primarily LHCP and a second signal of the two different signals has primarily RHCP.

Abstract: A radio frequency (RF) aperture includes an interface board. An array of electrically conductive tapered projections have bases disposed on a front side of the interface printed circuit board and extend away from the front side of the interface printed circuit board. RF circuitry is disposed at the back side of the interface board and is electrically connected with the electrically conductive tapered projections.

Abstract: Methods and apparatus for adaptive surge protection are disclosed. An example method comprises providing load voltage to the electric load by regulating a source voltage with a surge protection device; monitoring, via a voltage detection circuit, the source voltage from an electric source, and determining, via a wiring diagnostic circuit, whether a wiring fault is detected; monitoring, via a lightning detection circuit, for the presence of lightning within a threshold distance of the surge protection device; and breaking, with a switching device, a circuit connection to stop providing the load voltage to the electric load in response to detecting at least one of: a presence of the wiring fault, the presence of lightning within the threshold distance, an overvoltage at the source voltage; or an undervoltage at the electric source.

Abstract: Various examples are provided for point symmetric complementary meander line (PSC-ML) slots, which can be used for mutual coupling reduction. In one example, an antenna array includes first and second patch antenna elements disposed on a first side of a substrate, the first and second patch antenna elements separated by a gap. The antenna array can include point symmetric complementary meander line (PSC-ML) slots formed in a ground plane disposed on a second side of the substrate. The PSC-ML slots can include a pair of ML slots aligned with the gap between the first and second patch antenna elements. In another example, a method includes forming first and second antenna elements on a first side of a substrate and forming PSC-ML slots in a ground plane disposed on a second side of the substrate that are aligned with a gap between the first and second antenna elements.

Abstract: Modulation patterns for surface scattering antennas provide desired antenna pattern attributes such as reduced side lobes and reduced grating lobes.

Abstract: A broadband conformal antenna (“BCA”) is disclosed. The BCA includes a narrow approximately rectangular outer conductive (“NARO”) housing, a plurality of dielectric layers within the NARO housing forming a laminated dielectric structure, and an inner conductor formed within the laminated dielectric structure. The NARO housing includes a top broad wall and the BCA further includes an antenna slot within the top broad wall. The BCA is configured to support a transverse electromagnetic signal within the NARO housing.

Abstract: An embodiment of an antenna module includes a substrate, a first antenna, and a second antenna. The first antenna is disposed on the substrate and is configured to radiate a first signal having a wavelength and a first polarization. And the second antenna is disposed on the substrate and is configured to radiate a second signal having the wavelength and a second polarization that is approximately orthogonal to the first polarization. For example, such an antenna module can include, as the first antenna, a T antenna configured to transmit and receive data that forms a first part of a MIMO-OFDM data symbol, and can include, as the second antenna, an F antenna configured to transmit and receive data that forms a second part of the MIMO-OFDM data symbol.

Abstract: An antenna includes a feed; a first member being made of metallic materials and including an end plate and side wall plates disposed on both sides of the end plate, in which the feed is disposed on the end plate of the first member, and slots are respectively formed on the side wall plates of the first member; and second members made of non-metallic materials and bonded to the first member to shield the slots. The antenna and a mobile terminal including the antenna can achieve an aesthetically pleasing appearance and improve user experience, as the slots cannot be observed when viewed from outside the mobile terminal.

Abstract: A wireless module including: a substrate that includes a first surface and a second surface on the back side of the first surface; a plurality of signal terminals that are provided on the first surface and the second surface, input and output signals; an antenna provided on the first surface; a signal processing circuit that is provided on the second surface, is connected between the signal terminals and the antenna, and performs various signal processings on signals input from the signal terminals and the antenna; wherein the signal terminals are arranged in horizontal symmetry on the first surface and the second surface, arranged at the same positions of the first surface and the second surface, and connected to a single signal line in the substrate.

Abstract: A radar system includes a traveling-wave imaging manifold (TIM) antenna including a waveguide with multiple paths configured such that adjacent ones of the multiple paths have different path lengths. The radar system also includes a processor configured to generate a transmit signal to be input at an opening of the waveguide or to process a reflection obtained from the opening of the waveguide.

Abstract: A top fed, wide band, dual pitch, quadrifilar helix antenna with hemispherical radiation pattern coverage with a reduced back lobe over a wide bandwidth is described wherein one end of the antenna's helix has a high pitch angle that adjoins the other end of the helix with a low pitch angle. The dual pitch angles provide stable radiation patterns and exceptional impedance response to support ultra-high frequency, ultra-high frequency follow-on and mobile user object system circuits. Broadband performance is further aided by providing a radome that dielectrically loads the antenna.

Abstract: An interleaved array of electronically steerable antennas is capable of simultaneously operating and/or independently beam scanning at different frequencies from a single aperture. An antenna system may comprise a plurality of electronically steerable antennas configured to be operable at different frequencies, each of the antennas comprising a feed launching a surface wave and surface-wave waveguides connected to the feed. The surface-wave waveguides of the antennas operable at different frequencies may be interleaved with each other.

Abstract: A dipole antenna array element using crossed dipoles is provided. The arms of the crossed dipoles are spaced apart from a ground plane. The length of the arms of the crossed dipoles, as well as the height of the array element, is dependent on the lowest wavelength of signal for which the element is to be used with. To adjust the impedance of the antenna array element, a strip of conductive material is used to enclose an area about the arms of the dipoles. A patch component can also be used with the arms being between the patch component and the ground plane.

Abstract: An electronic device may include ground structures and peripheral conductive housing structures defining opposing edges of a slot element. A monopole element may overlap the slot element. The monopole element may be directly fed radio-frequency signals by an antenna feed coupled to the monopole element. The monopole element may radiate the radio-frequency signals in a first frequency band while indirectly feeding the radio-frequency signals to the slot element via near-field electromagnetic coupling. The slot element may radiate the radio-frequency signals in a second frequency band that is lower than the first frequency band. The monopole element and the slot element may collectively form a multi-band antenna that exhibits a relatively wide bandwidth.

Abstract: An improved Vivaldi antenna enhances the performance over a 2:1 frequency band while occupying a compact format. Taking advantage of a common FR4 material printed circuit board construction, considered features are added which improve the operating bandwidth without adding additional cost. One such embodiment operates over an approximate frequency range of 400 to 900 MHz.

Abstract: The present invention discloses a method of transmitting signal by a terminal. The method comprises determining a direction of at least one antenna based on power loss tolerance of the signal and angle tolerance of the at least one antenna; and transmitting the signal based on the direction of the at least one antenna, wherein the power loss tolerance of the signal is determined at maximum of 2 dB.

Abstract: An electronic device may include a peripheral conductive housing sidewall with an integral ledge extending towards the device interior. A display cover layer may be supported by the integral ledge. A slot antenna may be formed from a slot in the integral ledge. The integral ledge may be mounted to a surface of a substrate and coupled to a conductive rear housing wall by a conductive layer extending over an additional surface of the substrate. The sidewall may include a vertical portion extending from the ledge to the rear wall. The slot antenna may be fed via near-field coupling using a conductive patch that is located within the slot at the surface of the substrate. The conductive layer, rear housing wall, and vertical portion may form a cavity for the slot antenna. The conductive layer may isolate the slot from interference with a battery, display circuitry, or other components.

Abstract: The present subject matter relates to a wireless virtual reality (VR) docking station. In an example implementation of the present subject matter, the wireless VR docking station includes a first array antenna and a second array antenna disposed on a bezel of the wireless VR docking station. Each of the first array antenna and the second array antenna has an omnidirectional radiation pattern and is folded into two parts such that a first part transmits signals on one side of the bezel and a second part transmits signals on another side of the bezel.

Abstract: An apparatus and associated method are provided involving a housing having a periphery configured to operate as a second antenna, a third antenna, and a fourth antenna. The periphery includes a top wall having a first slot formed therein, a first side wall having a second slot formed therein, and a second side wall having a third slot formed therein. The top wall is arranged between the first side wall and the second side wall, and a top portion of the periphery is defined between the second slot and the third slot. The top portion is divided into a first top side portion and a second top side portion via the first slot. Further, the first top side portion operates as the second antenna, and the second top side portion operates as both the third antenna and the fourth antenna.

Abstract: An embodiment of an antenna module includes a substrate, a first antenna, and a second antenna. The first antenna is disposed on the substrate and is configured to radiate a first signal having a wavelength and a first polarization. And the second antenna is disposed on the substrate and is configured to radiate a second signal having the wavelength and a second polarization that is approximately orthogonal to the first polarization. For example, such an antenna module can include, as the first antenna, a T antenna configured to transmit and receive data that forms a first part of a MIMO-OFDM data symbol, and can include, as the second antenna, an F antenna configured to transmit and receive data that forms a second part of the MIMO-OFDM data symbol.

Abstract: A method for operating an antenna and an electronic device implementing the method are provided. The electronic device includes a power feed module including a first power feed terminal and a second power feed terminal, a current supply module configured to select one of the first power feed terminal and the second power feed terminal and to supply an electric current to the selected power feed terminal, and an antenna module including a first antenna and a second antenna. The electronic device further includes a connection module configured to connect the power feed module and the antenna module, and a control module configured to control the current supply module. The connection module includes a plurality of wirings.

Abstract: A system includes a first aerial vehicle comprising one or more sensors configured to obtain an image of a worksite. The system also includes a controller configured to receive the image of the worksite, to generate a map of the worksite by overlaying information related to the worksite on the image, and to display the map via a display.

Abstract: The invention provides an antenna system, includes a system ground unit and a dual polarized millimeter wave antenna unit. The dual polarization millimeter wave antenna unit includes a first substrate layer, a second substrate layer and a third substrate layer, a ground layer attached to a side of the first substrate layer away from the second substrate layer and electrically connected to the system ground unit, a feeder sandwiched between the first substrate layer and the second substrate layer and a radiator fixed on one side of the third substrate layer away from the second substrate layer. The feeder is provided with a horizontally polarized feed port and a vertically polarized feed port. The feeder is coupled to the radiator. Compared with the relevant technology, the communication signal of the antenna system is strong and stable.

Abstract: Exemplary embodiments are disclosed of dual-band multiple-input multiple-output (MIMO) antennas. In an exemplary embodiment, an antenna generally includes a circuit board, a first antenna radiating element positioned on the circuit board, a second antenna radiating element positioned on the circuit board, and at least two antenna feeding elements extending from the circuit board. Each of the at least two antenna feeding elements is electrically connected with a different one of the first and second antenna elements.

Abstract: An electronic device may include a millimeter wave transceiver, a first antenna having a first resonating element at a first side of a substrate, and a second antenna having a second resonating element at a second side of the substrate. A first coplanar waveguide may convey millimeter wave signals between the transceiver and the first resonating element and a second coplanar waveguide may convey millimeter wave signals between the transceiver and the second resonating element. The first coplanar waveguide may be coupled to the first resonating element through the second coplanar waveguide. The second coplanar waveguide may be coupled to the second resonating element through the first coplanar waveguide. Ground conductors in the coplanar waveguides may form antenna ground planes for the first and second antennas while serving to maximize electromagnetic decoupling between the coplanar waveguides and thus isolation between the ports of the transceiver.

Abstract: Proposed is a millimeter-wave band communication device which does not generate spatial resonance in a cover shielding unnecessary radio waves from the outside. Disclosed is a millimeter-wave band communication device including: a substrate; a radio frequency circuit element for a millimeter-wave band provided on the substrate; and a cover made of a bulk material that covers at least a part of the radio frequency circuit element and a surface of the substrate, the cover being formed by blending a dielectric loss material in a base.

Abstract: Aspects of the subject disclosure may include, a system that includes a coupler having a structure that facilitates guiding electromagnetic waves along a transmission medium, wherein the electromagnetic waves propagate along the transmission medium without requiring an electrical return path, and a device coupled to an outer surface of the structure, wherein the device facilitates steering a wireless signal generated by a flow of an electrical current on the outer surface of the structure. Other embodiments are disclosed.

Abstract: A radiator is formed by forming a multitude of slot antennas adjacent one another such that the spacing between each pair of adjacent slot antennas is smaller than the wavelength of the signal being transmitted or received by the radiator. The radiator achieves high efficiency by reducing the excitation of substrate modes, and further achieves high output power radiation by combining power of multiple CMOS power amplifiers integrated in the radiator structure. Impedance matching to low-voltage CMOS power amplifiers is achieved through lowering the impedance at the radiator ports. Each output power stage may be implemented as a combination of several smaller output power stages operating in parallel, thereby allowing the combination to utilize an effective output device size commensurate with the impedance of the radiator.

Abstract: Broadband antennas are described that include a quad-ridge horn inside which two different lenses are inserted creating a broadband horn-lens combination. One of these lenses is a cross-polyrod lens, formed from a pair of polyrods disposed in a crossed arrangement, each polyrod shaped in a predetermined manner. The other one of these lenses is a prolate spheroidal lens. The broadband antennas can produce, at the output thereof, Gaussian-like beams in both principal polarizations from VHF to 20 GHz. As such, the broadband antennas can be used to perform material measurements in a compact admittance tunnel. Simulation results show that directivity of quad-ridge horns can be improved using the combination of lenses of the broadband antennas. Therefore, the broadband antennas can also be of interest for far-field radiation applications.

Abstract: A rectangular waveguide device is provided. The rectangular waveguide device comprising: a first broad wall; a second broad wall parallel to the first broad wall; a first narrow wall perpendicular to and connected to the first broad wall and the second broad wall; a second narrow wall parallel to the first narrow wall and connected to the first broad wall and the second broad wall; and at least one slot in the first broad wall.

Abstract: A wireless device comprises a radiating structure that comprises a ground plane layer etched on a PCB, including a clearance area nearby one edge of the PCB, and an antenna element mounted on the clearance area. The radiating structure is included in a radiating system that also includes a radiofrequency system comprising at least a matching network, including more than three components. The radiofrequency system connects the antenna element to a feeding line connected at its end to an external port. The antenna element features a maximum length within the 22-30 mm range to match the radiating system in the multiple frequency bands of operation. In general, a radiating system features extended bandwidth, typically including LTE700 bands or below. The antenna element may include two conductive adjacent surfaces with a convex shape connected between them.

Abstract: A mobile device including a ground plane, a grounding branch, wherein a slot is formed between the ground plane and the grounding branch, a connecting element, wherein the grounding branch is electrically coupled through the connecting element to the ground plane and a feeding element, extending across the slot, and electrically coupled between the grounding branch and a signal source, wherein an antenna structure is formed by the grounding branch and the feeding element.

Abstract: A low profile, 4-element, slot-based, frequency reconfigurable MIMO antenna for cognitive radio (CR) platforms for cellular communication front ends. The antenna is on a board having a top layer substrate and a bottom layer ground plane. The bottom layer ground plane contains four antenna elements, each antenna element having a circular slot and an annular slot spaced outwardly from and extending circumferentially around the circular slot. The bottom layer contains a microstrip feed-line for each antenna element. Varactor diodes on the top layer span the width of each annular slot to tune the resonance frequency over a wide operation band. The antenna covers a wide frequency band from 1800 MHz to 2450 MHz and supports several well-known wireless standards bands, including GSM1800, LTE, UMTS and WLAN, as well as many others.

Abstract: Various embodiments may provide a device for controlling an electromagnetic wave. The device may include a first electrode layer. The device may also include a second electrode layer. The device may further include a matrix layer between the first electrode layer and the second electrode layer. The matrix layer may include a liquid crystal layer. The matrix layer may also include at least one resonator element in contact with the liquid crystal layer. The liquid crystal layer may be configured to switch from, at least, a first state to a second state in response to a voltage applied between the first electrode layer and the second electrode layer, thereby changing an optical property of the matrix layer to control the electromagnetic wave received by the matrix layer.

Abstract: A transmission conduit for RF signal, comprising: a dielectric plate; a conductive circuit positioned on one surface of the dielectric plate; a conductive ground positioned on opposite surface of the dielectric plate; wherein the dielectric plate comprises a sandwich of at least one high-dielectric constant layer and one foam plate. The dielectric plate can be made of a sandwich of glass and foam plate, such as Rohacell®. The glass and foam plates have thickness calculated to give the sandwich the required overall dialectic constant.