Abstract: A dielectric strip is located in a space formed by facing grooves in two conductors. A corner of the groove bottom surface Gb has a sectionally substantial arc form. A groove side surface Gs is tapered such that a gap can be provided between the groove side surface Gs and the side surface of the dielectric strip.

Abstract: A method and apparatus for providing communication signals via air or other ducting in a building. Two-way mobile telephone communications between a mobile telephone in a building and an antenna in one or more air ducts may be provided. In one embodiment, wireless communication between at least two antennas in a ventilation duct and rooms and spaces in a building may be provided without the use of bi-directional couplers or re-radiators. In another embodiment, a first signal may be emitted from an antenna in a ventilation duct of a building and the first signal transmitted by the duct for passage through an opening into a room or space in the building. A second signal may be received into the duct through the opening and transmitted by the duct from the opening for reception by the antenna.

Abstract: A pressure equalization apparatus for decreasing or eliminating the pressure differential between the internal pressure within a sealed system and the external ambient air pressure while concurrently sustaining a dry atmosphere inside the enclosure. The apparatus includes a variable volume chamber coupled in fluid communication with the sealed system and adapted to change its volume as in relation to the pressurization of the sealed system. Gas flowing between the sealed system and the variable volume chamber, as the pressurization changes, is exposed to an adsorbent operative for dehumidifying the exchanged gas.

Abstract: A low cost and high performance millimeter wave (MMW) radio frequency transceiver module includes a substrate board and plurality of microwave monolithic integrated circuit (MMIC) chips supported by the substrate board and arranged in a receiver section, a local oscillator section and a transmitter section. A plurality of filters and radio frequency circuit interconnects are formed on the substrate board and operative with and/or connecting the receiver, local oscillator and transmitter sections. A plurality of electrical interconnects are operative with and connect the receiver, local oscillator and transmitter sections. A method of forming the millimeter wave radio frequency transceiver module is also disclosed.

Abstract: A waveguide device that includes a waveguide device body having interior surfaces, a deposited aluminum coating disposed on the interior surfaces of the waveguide device body, a protective coating disposed on the deposited aluminum coating.

Abstract: A wiring board module has two wiring boards placed on an external circuit board. In each wiring board, a terminal end of a laminated waveguide tube is exposed at a lateral side of a dielectric substrate, thus forming an exposed face, and the dielectric substrate is provided at the bottom thereof in the vicinity of the exposed face with connection pads to be used for mounting the wiring board on the surface of the external circuit board. The exposed faces of the laminated waveguide tubes of the two wiring boards are contacted with each other, and the connection pads at the bottoms of the wiring boards are connected and fixed to connection pads disposed on the surface of the external circuit board.

Abstract: A waveguide is disclosed that shifts the phase of the signal passing through it. In one embodiment, the waveguide has an impedance structure on its walls that resonates at a frequency lower than the frequency of the signal passing through the waveguide. This causes the structure to present a capacitive impedance to the signal, increasing its propagation constant and shifting its phase. Another embodiment of the new waveguide has impedance structures on its wall that are voltage controlled to change the frequency at which the impedance structures resonate. The range of frequencies at which the structure can resonate is below the frequency of the signal passing through the waveguide. This allows the waveguide cause a adjust the shift in the phase of its signal. An amplifier array can be included in the waveguides to amplify the signal. A module can be constructed of the new waveguides and placed in the path of a millimeter beam.

Abstract: A first waveguide groove is formed in a sidewall of a main casing housing a first circuit board, and a second waveguide groove is formed in a sidewall of a sub-casing hermetically housing a second circuit board such that the first waveguide groove is in continuous connection with the second waveguide groove. Further, a lid is attached to the sidewall of the main casing so as to cover the first and the second waveguide grooves, and a probe provided on the second circuit board protrudes into the second waveguide groove. In addition, an inclined plane is formed at an end of the first waveguide groove so as to be in continuous connection with a through-hole provided in the lid.

Abstract: A center-pivoted, conductive vane equipped with contact-enhancing finger stock on the wiping edges rests during normal operation of a modified waveguide section parallel to and equidistant between the broad faces of the waveguide, where it interacts minimally with RF propagating through the waveguide. When it is desired to provide a short circuit to the waveguide, for a safety lockout or other uses, the vane can be rotated into a position to provide a substantial barrier to RF propagation. Rotating the pivot shaft, to which the vane is rigidly attached, performs rotation of the vane. The shaft is equipped with lockable stops for the open and shorted positions. Multiple center-pivoted vanes in a multiple-branch waveguide can form a switch.

Abstract: Waveguides and backplanes systems are disclosed. A waveguide according to the present invention includes a first conductive channel, and a second conductive channel disposed generally parallel to the first channel. A gap is defined between the first and second channels that allows propagation along a waveguide axis of electromagnetic waves in a TE n,0 mode, wherein n is an odd number, but suppresses electromagnetic waves in a TE m,0 mode, wherein m is an even number. An NRD waveguide is disclosed that includes an upper conductive plate and a lower conductive plate, with a dielectric channel disposed between the conductive plates. A second channel is disposed adjacent to the dielectric channel between the conductive plates. The upper conductive plate has a gap above the dielectric channel that allows propagation along a waveguide axis of electromagnetic waves in an odd longitudinal magnetic mode, but suppresses electromagnetic waves in an even longitudinal magnetic mode.

Abstract: The invention relates to a microwaveguide that is integrated in the dielectric layer of a conductor carrier, e.g. a printed circuit board. The waveguide enables different types of active and/or passive functions intended to influence the signals sent through the waveguide to be integrated at appropriate positions in the waveguide.

Abstract: A waveguide structure that has two rotating parts changes the polarization of a radio frequency signal in two steps or one step. The waveguide structure includes input and output waveguides and a polarization rotator. The output waveguide includes two cavities corresponding to two polarizations. The rotator includes cut-away portions of a rectangular shape which are rotated with respect to each other and the first wave guide by predetermined angles. When the second waveguide is rotated from one cavity to another, the rotator is also rotated, thereby changing the polarization of the signals passing through the waveguide. In addition, if the rotator and the second waveguide are interlocked, then the number of steps required to accomplish the polarization change can be reduced to one, because rotation of the second waveguide will cause the rotation of the polarization rotator.

Abstract: An interconnection system comprises mating male and female connectors. The male connector has a first end with an outer face and a second end with an inner face, an aperture passing through the center, radially extending flanges coplanar with the inner face and recesses formed between the flanges with a first circumference. The female connector has a central aperture passing there through, receivers with lips having an edge with the first circumference. When mated in the locked state, the flanges of the male connector form a coplanar coupling with the receivers of the female connector with the central apertures aligned and at least one bore passing through both connectors.

Abstract: A waveguide structure that has two rotating parts changes the polarization of a radio frequency signal in two steps or one step. The waveguide structure includes input and output waveguides and a polarization rotator. The output waveguide includes two cavities corresponding to two polarizations. The rotator includes cut-away portions of a rectangular shape which are rotated with respect to each other and the first wave guide by predetermined angles. When the second waveguide is rotated from one cavity to another, the rotator is also rotated, thereby changing the polarization of the signals passing through the waveguide. In addition, if the rotator and the second waveguide are interlocked, then the number of steps required to accomplish the polarization change can be reduced to one, because rotation of the second waveguide will cause the rotation of the polarization rotator.

Abstract: A device is disclosed for converting a circularly polarized electromagnetic radiation into linearly polarized electromagnetic radiation. The device includes a depolarizer with depolarizing elements supported in a polarization mode converter for rotation between a vertical output and a horizontal output. A depolarization position for circularly polarized radiation exists between the horizontal output and the vertical output. The rotation direction of the depolarizer can be adjusted to selectively direct left-handed circularly polarized and right-handed circularly polarized radiation either to the vertical or the horizontal output.

Abstract: The present invention is a waveguide transition and port structure, comprised of two distinct rectangular waveguide sections, with one section angularly displaced with respect to the other by 45 degrees about a common longitudinal axis. The orientation of the two waveguide sections enables the waveguide transition and port structure to rotate a polarized signal by 45 degrees such that, when coupled to an external device, as part of an antenna or other receiving or transmitting apparatus, either vertical or horizontal polarization of the signal can be effected with equal degrees of efficiency and without the need to change or reorient components, such as waveguides or twists.

Abstract: A waveguide bi-directional amplifier module is illuminated by a downstream illumination source and an upstream illumination source. The illumination sources are coupled to an array having waveguide to microstrip converters that provide for upstream and downstream electrical signals. Switchable amplifiers provide for amplification in both directions for the electrical signals and the converters coherently combine the output of the amplifiers to provide increased power to the electromagnetic wave entering the waveguide.

Abstract: A coplanar waveguide, which has parallel conductor strips that are arranged on a substrate and have an electrically insulating intermediate space between one another, wherein a material with a high dielectric constant is arranged on the conductor strips, on their side facing away from the substrate. In this way, it is possible to achieve a line section with a relatively small characteristic impedance.

Abstract: A broadband impedance matching circuit for use with an optical device such as an electroabsorption optical modulator comprises a microstrip transmission line, including pairs of like-sized open stubs disposed on opposite sides of the transmission line along its length. The number of open stubs, as well as their dimensions and location are chosen to provide for broadband impedance matching (from dc to several GHz) between an external electrical signal source and the optical device.

Abstract: A waveguide assembly for operation over a range of temperatures includes a waveguide body and a plurality of restraining strips coupled to the waveguide body. The waveguide body includes a pre-curved narrow sidewall of material having a first coefficient of thermal expansion (CTE). The restraining strips are coupled to the waveguide body at first and second lateral points on either side of the pre-curved narrow sidewall laterally and are spaced apart along the length of the waveguide body, and are made from a material having a second CTE much less than the first CTE.

Abstract: A dielectric transmission line attenuator or terminator, which is used with a dielectric transmission line provided with two conductive plates substantially parallel to each other and a dielectric strip held between the two conductive plates. A resistor film pattern is provided along a surface defined where upper and lower parts of the dielectric strip are divided, and substantially parallel to the two conductive plates. The resistor film pattern and the two conductive plates form a transmission line, and the dielectric transmission line and the transmission line are coupled.

Abstract: A surface-mountable millimeter-wave waveguide filter is constructed using irises in a rectangular waveguide formed in a dielectric material such as glass. The filter structure is surface-mountable, has a single dielectric layer, and can be manufactured using a suitable monolithic microwave integrated circuit (MMIC) process. The filter has potential applications in millimeter-wave systems such as Local Multipoint Distribution System (LMDS) and Autonomous Cruise Control (ACC) radar for automobiles.

Abstract: A waveguide apparatus for bidirectional distribution of signals includes: (a) a first conductive element parallel with a reference plane; (b) a second conductive element in spaced parallel relation with the first element; (c) a first coupling locus situated in the first element; and (d) second coupling loci arrayed in the second element. Each second coupling locus includes an aperture traversing the second element at a lineal distance from the first coupling locus in a lineal plane perpendicular with the reference plane and containing a line from the first coupling locus. Each aperture has a major and a minor axis. The major axis establishes an installation attitude with respect to the lineal plane. The lineal distance and the installation attitude for each aperture are selected to distribute electromagnetic signals having substantially equal power.

Abstract: An “inside out” process is used to make RF antennas and components or higher frequency components and/or optics. This invention is especially useful for spaceflight components requiring high performance at low weight, components requiring high specific stiffness and/or strength and components requiring high performance, precision or stability. An electroformed single or multi layer of metal, such as copper, is applied to a reusable or disposable mandrel. Additional metal or composite components and/or pieces may be attached to the electroform by means of further electroforming, and/or applying adhesive and/or soldering. Any composite material (for example, fiberglass or carbon fiber reinforced plastic) is then applied selectively or uniformly around the electroform and/or additional components for structural reinforcement, and/or enhancement of thermal stability and/or thermal conductivity. The mandrel is then removed by physical or chemical means.

Abstract: The attenuator includes two variable-section components (13, 15) for the passage, in conditions of perfect adaptation, from a first wave-guide in the P band to a second wave-guide in the X band and vice versa. An air-filled zone (5V), the length of which can be varied in function of the desired attenuation, is situated between the two variable-section components.

Abstract: A multi layered high impedance structure presents a high impedance to multiple frequency signals, with a different frequency for each layer. Each layer comprises a dielectric substrate, and an array of radiating elements such as parallel conductive strips or conductive patches on the substrate's top surface with a conductive layer on the bottom surface of the bottommost layer. The radiating elements of succeeding layers are vertically aligned with conductive vias extending through the substrates to connect the radiating elements to the ground plane. Each layer presents as a series of parallel resonant L-C circuits to an E field at a particular signal frequency, resulting in a high impedance surface at that frequency. The new structure can be used as the substrate for a microstrip patch antenna to provide an optimal electrical distance between the resonator and backplane at multiple frequencies.

Abstract: When manufacturing waveguides, for example densely located waveguide channels, for electromagnetic waves such as microwaves, the channels are produced from rod-shaped bodies (1) of a material permeable to the waves and non significantly attenuating the waves. The bodies (1) can for example project from a base plate (3) and their side surfaces are coated with electrically conducting material but not their free end surfaces (5). The interior of the bodies form the waveguiding channels, which have their walls formed from the layer of electrically conducting material. By giving the rod-shaped bodies suitable shapes for example an antenna side or half of a waveguide antenna can be manufactured. The rod shaped bodies can before applying the electrically conducting material be coated with one or several layers of non-attenuating and non-conducting lacquer filling pores and smoothing the surface of the bodies.

Abstract: A surface-mountable millimeter-wave waveguide filter is constructed using irises in a rectangular waveguide formed in a dielectric material such as glass. The filter structure is surface-mountable, has a single dielectric layer, and can be manufactured using a suitable monolithic microwave integrated circuit (MMIC) process. The filter has potential applications in millimeter-wave systems such as Local Multipoint Distribution System (LMDS) and Autonomous Cruise Control (ACC) radar for automobiles.

Abstract: A waveguide is disclosed that shifts the phase of the signal passing through it. In one embodiment, the waveguide has an impedance structure on its walls that resonates at a frequency lower than the frequency of the signal passing through the waveguide. This causes the structure to present a capacitive impedance to the signal, increasing its propagation constant and shifting its phase. Another embodiment of the new waveguide has impedance structures on its wall that are voltage controlled to change the frequency at which the impedance structures resonate. The range of frequencies at which the structure can resonate is below the frequency of the signal passing through the waveguide. This allows the waveguide cause a adjust the shift in the phase of its signal. An amplifier array can be included in the waveguides to amplify the signal. A module can be constructed of the new waveguides and placed in the path of a millimeter beam.

Abstract: An improved waveguide wall structure and improved waveguide using the new wall structure as the interior walls of the waveguide. The wall structure comprises a sheet of dielectric material, a series of parallel conductive strips on one side of the dielectric material and a layer of conductive material on the other side. Multiple conductive vias are also included through the dielectric material and between the conductive layer and conductive strips. The new wall structure presents as a series of parallel L-C circuits to a transverse E field at resonant frequency, resulting in a high impedance surface. The wall structure can be used in waveguides that transmit a signal in one polarization or signals that are cross polarized. The new waveguide maintains a near uniform density E field and H field component, resulting in near uniform signal power density across the waveguide cross section.

Abstract: A radio repeater wherein a reflective negative resistance amplifier, using the negative resistance of a Gunn diode, is applied at one side of a dielectric waveguide, enabling signals to be inputted through the input terminal dielectric waveguide, circulated in the circulator and enter the Gunn diode. Reflected waves amplified in the Gu diode exit the output terminal dielectric waveguide. A radio repeater is provided on the non-radiative dielectric waveguides using the multi-space non-radiative dielectric waveguides, which receives a frequency, amplifies it, and retransmits the amplified signals to any direction. With a dielectric band inserted in the radio repeater, directions for reception and transmission can be freely changed. Using the radio repeater, a small size radio repeater of low power consumption may be made.

Abstract: A waveguide assembly including a waveguide, a backshort member, and an adjustment member, where the adjustment member is capable of receiving or input and transforming it into an output that causes the backshort member to be displaced in response to said input.

Abstract: Waveguides and backplanes systems are disclosed. A waveguide according to the present invention includes a first conductive channel, and a second conductive channel disposed generally parallel to the first channel. A gap is defined between the first and second channels that allows propagation along a waveguide axis of electromagnetic waves in a TE n,0 mode, wherein n is an odd number, but suppresses electromagnetic waves in a TE m,0 mode, wherein m is an even number. An NRD waveguide is disclosed that includes an upper conductive plate and a lower conductive plate, with a dielectric channel disposed between the conductive plates. A second channel is disposed adjacent to the dielectric channel between the conductive plates. The upper conductive plate has a gap above the dielectric channel that allows propagation along a waveguide axis of electromagnetic waves in an odd longitudinal magnetic mode, but suppresses electromagnetic waves in an even longitudinal magnetic mode.

Abstract: An apparatus and method stabilizes a pair of parallel coaxial lines for an antenna having a tower. An upper portion of each coaxial line is suspended from the tower. A lower end of the coaxial lines is free to move vertically relative to the tower. The apparatus has an expandable element disposed along a first portion of the length of one coaxial line and a frame which rigidly ties together the two coaxial lines at a second portion of each of the lines below the expandable element. One type of expandable element includes telescoping inner conductors and telescoping outer conductors.

Abstract: The microwave applicator for microwaves outputs from a guide (1) comprises an envelope (3) that forces microwaves to converge towards a focal point (16) by means of a complementary central reflector (4). A fraction of the waves reaches this point after reflection on two facets (11, 13), usually curved and concave, of the reflector (4) and the envelope (3), while the other fraction is reflected three times on three facets (10, 12 and 14), the last two facets of which form part of the envelope and one of which is concave for focussing. These devices can be used for removing a concrete surface, because the microwaves cause vaporisation at the focal point (16).

Abstract: In a high-frequency transmission line that is used in a high-frequency band such as the microwave band or the millimeter wave band, at least one resistive film is disposed in a plane that is substantially perpendicular to an electric field of an operating transmission mode, and the resistive film attenuates, by dielectric loss, an unwanted mode having an electric field that is perpendicular to the electric field of the operating transmission mode.

Abstract: An orthogonal electrical coupling relies on electromagnetic coupling for the inner connection, as opposed to direct contact between conductors. A conductor on one of the lines is connected to a ground plane which is adjacent to a resonant slot. Microwave energy is coupled to the slot, thereby exciting the slot. A second conductor is on the opposite side of the ground plane from the first conductor. Microwave energy from the excited resonant slot passes to the second conductor, thereby allowing contactless interconnection between the first conductor and the second conductor. The coupling may emphasize certain modes of propagation relative to other possible modes of propagation. Specifically, the ground plane and slot may be enclosed in a cavity of a size such that the cavity does not support any natural mode propagation inside the cavity. Instead, the coupling may have a cavity in which a transverse electromagnetic (TEM) mode is propagated.

Abstract: A converter for satellite broadcast reception superior in productivity and inexpensive with reduced material cost is provided. In this converter, a waveguide is formed by bending a metallic plate and is integrally provided with a holding portion which is positioned outside the waveguide. An insulating portion of a probe is held by the holding portion.

Abstract: An electromagnetic enclosure is provided that this configured to enclose an electrical assembly. The enclosure includes a waveguide defining a channel that one or more cables from the electrical assembly pass through. The waveguide is dimensioned to attenuate radiation having a selected frequency range. With the present invention, shielding emitted or transmitted radiation around an opening in an enclosure and around cables can be easily done.

Abstract: A resonant waveguide load structure is provided for use in waveguide systems. The load structure includes a length of waveguide which is open at one end and closed at the other end. The load structure also includes a support pin mounted inside the waveguide near the closed end thereof. The load structure further includes a resonant body mounted on the support pin. The load structure also includes at least one spacer member mounted on the support pin for maintaining the position of the resonant body. This load structure may be combined with a waveguide circulator to provide a novel waveguide equalizer apparatus.

Abstract: A waveguide assembly including a waveguide, a backshort member, and an adjustment member, where the adjustment member is capable of receiving or input and transforming it into an output that causes the backshort member to be displaced in response to said input.

Abstract: A directional coupler includes two non-radiative dielectric lines, each formed by a dielectric strip between flat conductive surfaces placed substantially parallel to each other, such that the two non-radiative dielectric lines are close to each other. The main transmission mode of electromagnetic waves at the frequency used is an LSE mode, the electromagnetic waves being propagated in the non-radiative dielectric lines. Therefore, the insertion loss due to mode switching in the coupling portion of the primary line and the secondary line which form the directional coupler can be reduced, and leakage of the electromagnetic waves from the gap between the primary line and the secondary line of the directional coupler when they are separated from each other can be suppressed.

Abstract: An object of the present invention is to provide an NRD guide which can be used in a wide band in a state where output levels of distributed high-frequency signals are nearly equal and does not require precise positioning, thereby enhancing mass productivity thereof. The NRD guide comprises a first straight dielectric strip made of cordierite ceramics having a dielectric constant of 4.8 and a dielectric loss of 2.7×10−4 (at a measurement frequency of 77 GHz) and having a section of 1.0 mm width×2.25 mm height, and a second dielectric strip joined to the first dielectric strip at a midway position thereof so as to be branched along an arc and bent at an angle of 90°, wherein the first and second dielectric strips are integrally produced, and the radius of curvature r of a junction (branched portion) of the second dielectric strip is 12.7 mm, which is larger than the wavelength &lgr;≈5 mm of high-frequency signals of 60 GHz.

Abstract: A resonator including a lower substrate having a groove, a dielectric filling the groove, a material film formed on the inner wall of the groove, the material film for preventing the permittivity from suddenly changing between the lower substrate and the dielectric, an upper substrate that is combined with the lower substrate to form a cavity, a conductive thin film formed on the lower surface of the upper substrate to face the dielectric and having a slot in contact with the material film and exposing the dielectric, and a strip line for a wave-guide that is formed on the upper part of the upper substrate and is connected to the conductive thin film. According to the resonator, the size of a cavity corresponding to a given resonance frequency can be reduced by filling a cavity with a dielectric (or magnetic material).

Abstract: A waveguide assembly including a waveguide, a backshort member, and an adjustment member, where the adjustment member is capable of receiving or input and transforming it into an output that causes the backshort member to be displaced in response to said input.

Abstract: An electromagnetic enclosure is provided that this configured to enclose an electrical assembly. The enclosure includes a waveguide defining a channel that one or more cables from the electrical assembly pass through. The waveguide is dimensioned to attenuate radiation having a selected frequency range. With the present invention, shielding emitted or transmitted radiation around an opening in an enclosure and around cables can be easily done.

Abstract: A resonator including a lower substrate having a groove, a dielectric filling the groove, a material film formed on the inner wall of the groove, the material film for preventing the permittivity from suddenly changing between the lower substrate and the dielectric, an upper substrate that is combined with the lower substrate to form a cavity, a conductive thin film formed on the lower surface of the upper substrate to face the dielectric and having a slot in contact with the material film and exposing the dielectric, and a strip line for a wave-guide that is formed on the upper part of the upper substrate and is connected to the conductive thin film. According to the resonator, the size of a cavity corresponding to a given resonance frequency can be reduced by filling a cavity with a dielectric (or magnetic material).

Abstract: An apparatus for forming a quarter wave step between a waveguide of a radiating element under test and a waveguide associated with test equipment being used to test the radiating element. The apparatus includes a housing including a first bore, a second bore and a third bore, with the second bore forming a quarter wave step between the first and third bores. A pair of circuit boards each including a ring resonator are disposed at the transition areas between the first and second bores and the second and third bores. The ring resonators cancel the reactive component that would otherwise be introduced into the propagating wave as it travels through the quarter wave step portion of the apparatus. The apparatus is relatively short in length and easily implemented in a test environment to test various microwave components.

Abstract: A method for measuring harmonic load-pull including supplying a fundamental frequency signal to a frequency multiplication device under test and obtaining a target even-order multiplied frequency signal. The fundamental load impedance and an even-harmonic load impedance are independently controlled with a load mechanical tuner having an open-ended stub that is one-quarter wavelength long at the fundamental frequency and satisfies a short-circuit condition with respect to the fundamental signal. A fundamental source impedance and an even-harmonic source impedance of an input signal applied to the device under test are independently controlled with a source mechanical tuner having a short-circuit stub that is one-quarter wavelength long at the fundamental frequency and satisfies a short-circuit condition with respect to even-harmonics.

Abstract: A connection structure for dielectric waveguide lines, which includes dielectric waveguide lines including dielectric substrates, a pair of main conductor layers, dielectric substrates parallel with one another being sandwiched therebetween, two rows of side-wall through conductor groups arranged at intervals less than one half of a signal wavelength in a transmission direction of high-frequency signals, so as to electrically connect the pair of main conductor layers, and a sub conductor layer disposed between each pair of main conductor layers in parallel with the main conductor layers and electrically connected with the side-wall through conductor groups. The waveguides are stacked so that the main conductor layers partly overlap each other to define an overlap part, in which a coupling window is formed. This allows design freedom and easy fabrication.