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A compact double-sided contactless electromagnetic bandgap (DCEBG) structure is introduced in this letter. It consists of three metal plates placed in parallel, including two smooth metal plates and a corrugated metal plate in the middle. The middle plate is double-sided corrugated alternatively with a displacement of half period. The depth of the corrugations is about quarter wavelength of center frequency of its stopband. The thickness of the proposed DCEBG is slightly thicker than the depth of the corrugations. A double-sided contactless waveguide flange (CWF) based on the DCEBG is proposed. Compared with the back-to-back CWF in the form of bed of nails, the thickness is effectively reduced. A prototype of the double-sided CWF (DCWF) suited for standard WR75 waveguide is designed, manufactured, and tested. The measured insertion loss is less than 0.048 dB and the return loss is lower than 25 dB over the entire WR75 waveguide frequency band.

In this article, a simple and accurate method is proposed to extract the sheet resistance of a thin conductive film by using the enhanced one-port waveguide in a microwave frequency. A shorted quarter-wavelength waveguide is supplemented to the main waveguide as its open boundary to ensure the TE10 mode during the measurement. Unlike the available waveguide with the metal flange, the dielectric flange of the shorted quarter-wavelength waveguide is proposed to eliminate the transverse electromagnatic (TEM) wave propagation and leakage in the gap between two waveguide flanges. The conductive film deposited on the substrate is attached to the main waveguide flange, and the equivalent circuit model is generated thereof. By measuring S 11 parameters of the bare substrate and conductive film with the substrate, respectively, the unknown sheet resistance of the conductive film can be easily extracted. Even a large sheet resistance could be measured accurately. Both numerical and measurement results are presented for effectiveness validation of the proposed method. In comparison with the available dual-port method and waveguide with the metal flange method, the dielectric flange raises the measurement accuracy sharply in aspects of substrate thickness, substrate materials, and sheet resistance.

We propose a metasurface (MTS) structure integrated at the aperture of a flanged rectangular waveguide to produce dual-beam radiation. The dual beams are antiparallel in an orientation and perpendicular to the boresight direction. The MTS is backed by a dielectric slab to produce a substrate integrated waveguide-like response above the flange. The MTS is engineered to limit the boresight emission from the waveguide aperture, as well as to allow symmetric wave splitting between the MTS and waveguide flange. A lens-like end texturing involving surface tapering and electromagnetic bandgap cells is utilized to enhance the beam directivity at endfire from the flange. The dual-beam radiation exists for all frequencies between 10.5 and 12.4 GHz. The proposed design is modeled via full-wave simulation in commercial software, then validated through the measurement of a fabricated prototype.

This paper proposes a new concept of designing compact high precision millimeter-wave wideband variable phase shifters. The phase shifter is implemented with a stacked shim with extremely short length of 0.9 mm and two waveguide flange adaptors with length of 0.5 mm. High precision phase shifting is achieved over entire D-band (110-170 GHz) by rotating the shim 90 degrees from aligned to perpendicular with consistent impedance matching performance. In addition, a glide-symmetric holey electromagnetic bandgap (EBG) structure is adopted to avoid wave leakage from the gap between the shim and the flange adaptors. A proof-of-concept (PoC) demonstrator is designed, manufactured, and tested. The measured results show that the designed stacked shim phase shifter with embedded EBG structure ensures return loss higher than 10 dB across 110-170 GHz with a 75 μm airgap between waveguide flanges. The studied phase shifter provides a 0.88° phase shifting with each degree of mechanical rotation. The fabricated PoC phase shifter has a worst-case insertion loss of 0.92 dB and a return loss of 20 dB across the entire 110-170 GHz band and a maximum phase shift of 30°. At 10° phase shifting, the measured insertion loss is lower than 0.52 dB, and return loss is higher than 23 dB, respectively.

This article presents the design and fabrication of a micromachined 300 GHz planar array slotted waveguide antenna utilising the silver-coated SU-8 photoresist layer technology. The array is configured to be built from five SU-8 layers of equal thicknesses. The top layer is devoted to form the 8×8 slots. The following three layers are to form the feed and radiating waveguides. The bottom layer is to enclose the design and allocate the input port. An H-plane waveguide bend based on the matching steps is designed and integrated with the proposed array. This is to maintain a precise alignment with the standard waveguide flange WR-03 and facilitate the measurement. Also, two brass plates are used to clamp the five layers together and tight them via screws in order to minimise the losses. The simulated antenna realised gain is 24.59 dBi, and the 3-dB gain bandwidth is 4.5 GHz. The radiation patterns are very directive, having low side lobe levels. The reflection coefficient has been measured and presented. The proposed micromachined antenna array is directional and low-profile and may find applications in indoor wireless applications and sensors.

We propose a novel 600-GHz-band silicon dielectric waveguide module for terahertz-band applications. The I/O interface of the proposed module is compatible with a standard waveguide flange, WR-1.5, which is intended for use with other conventional hollow-waveguide-packaged components. The design and fabrication of the module is evaluated based on both simulation and experimental results. Using this module, an insertion loss as low as 0.2 dB was achieved, thereby indicating its superiority over the conventional metallic hollow waveguide in the 600 GHz band.

In this work, a WR-1.5 band-pass filter is presented, manufactured using the Polystrata 3D fabrication process. The filter is intended to be integrated into a radiometric receiver to band limit the incoming noise power and encompass an atmospheric spectral window centered at 682.5 GHz. A 10.8 mm diameter waveguide flange is fabricated in Polystrata with a band-pass filter structure running parallel to the flange face. The thickness of this standalone filter “shim” is 0.8 mm. The dimensions of the filter structure itself are 0.4 mm x 0.8 mm x 2.3 mm. The filter has a 3 dB bandwidth of 12 GHz, or 1.7%, and exhibits 4.5 dB insertion loss. These results are compared against standard CNC machine split-block waveguide iris filters at the same frequency to highlight the advantages of micromachined filters for terahertz applications.

Good electrical contact is always required between waveguide flanges of the test system and DUT to minimize leakage and losses that will degrade circuit performance. This requires the DUT to be tightly and carefully connected to avoid gaps and mismatches. This can be time consuming, especially when performing repeated measurements on multi-port devices. In this paper we present a contactless flange that can be used at millimeter-wave (mmW) and terahertz (THz) frequencies. Unlike conventional waveguide flanges, the contactless flange can be used to perform fast measurements because normal flange screws are not required. An E-band prototype has already been successfully designed, manufactured, and tested. The use of contactless waveguide flanges allows for faster, accurate, and reliable mmW and THz measurements.

Conductive nanomaterials are widely studied and used. The four-point probe method has been widely used to measure nanomaterials&rsquo, sheet resistance, denoted as . However, for materials sensitive to contamination or physical damage, contactless measurement is highly recommended if not required. Feasibility of evaluation using a one-port rectangular waveguide working on the microwave band in a contact-free mode is studied. Compared with existed waveguide methods, the proposed method has three advantages: first, by introducing an air gap between the waveguide flange and the sample surface, it is truly contactless, second, within the specified range of , the substrate&rsquo, s effect may be neglected, third, it does not require a matched load and/or metallization at the sample backside. Both theoretical derivation and simulation showed that the magnitude of the reflection coefficient decreased monotonously with increasing . Through calibration, a quantitative correlation of and was established. Experimental results with various conductive glasses showed that, for in the range of ~10 to 400 Ohm/sq, the estimation error of sheet resistance was below ~20%. The potential effects of air gap size, sample size/location and measurement uncertainty of are discussed. The proposed method is particularly suitable for characterization of conductive glass or related nanomaterials with in the range of tens or hundreds of Ohm/sq.

This paper presents a preliminary analysis on usage of graphene as reflect standard for vector network analyzer (VNA) calibration operating at millimeter-wave frequencies. As an example, WR03 waveguide flange is used for investigation. It is found that multilayer graphene exhibits reflection properties that makes it a suitable candidate for reflect standard to calibrate the VNA test setups operating at millimeter-wave frequencies. A parametric analysis to study the effects of graphene thickness, chemical potential and relaxation time on reflection coefficient has also been presented and discusse

Passive intermodulation (PIM) measurement is necessary for microwave and antenna products to evaluate their PIM performance. To achieve stable low residual PIM level of measurement system and make accurate PIM test, a compact waveguide flange adapter is proposed based on gap waveguide, dielectric filled bed of nails is adopted to construct compact double-sided artificial magnetic conductor (AMC) structure. When the adapter is connected between standard waveguide flanges, double-sided contactless electromagnetic band gap (EBG) structure with air gap is formed inside the flange connection. Electromagnetic leakage is prevented by stop band of the EBG structure. Meanwhile, metallic contact nonlinearity is almost eliminated by the contactless structure, and PIM can be therefore suppressed. A Ku band prototype of the adapter is designed for a Ku band PIM measurement system. By using the adapter, the system’s residual PIM is significantly improved with a maximum improvement better than 30 dB, achieving a stable low level.

To reduce the size of traditional waveguide flange, a solution of pluggable flangeless waveguide connection is proposed. Artificial magnetic conductor (AMC) structure is designed surrounding the outer surface of a size-reduced end of a waveguide, called part-A. Another waveguide with stepped transition to an enlarged end is part-B, the inner surface of the enlarged end works as PEC surface. When Part-A is inserted into part-B, a tight flangeless waveguide connection is achieved under proper size conditions. Tiny air gap exists between the PEC and AMC surface, the electromagnetic leakage from the air gap is prevented by band gap of the EBG structure formed by PEC and AMC surface. A Ku-band prototype of the flangeless connection is designed and manufactured, the measured insertion and return loss are better than 0.06dB and 20dB respectively over 10GHz to 15GHz. The sectional size decreases by more than 70% comparing with traditional waveguide flange.

This paper presents a simple, low-cost, hours-long fabrication method for microwave waveguide components of high RF performance. The technique combines 3-D-printed configurations with liquid metal waveguide structures. As a demonstration, a fused deposition modeling multimaterial 3-D consumer-grade printer and liquid gallium were used. A conductive polylactic acid (PLA) waveguide flange was 3-D printed along, in-one-go, with standard PLA for the rectangular waveguide liquid metal enclosures. Microwave WR62 waveguides, resonators, and filters operating in Ku-band were designed, fabricated, and tested. The RF performance of the fabricated waveguide devices is in agreement with the simulations demonstrating better than 1.29 dB/m attenuation in the waveguide and better than 1000 $Q$ -factor for the resonator and the filter at 13 GHz. The fabricated devices demonstrate a new option of an economical fabrication technology for high RF performance microwave waveguide-based devices that can be delivered in hours-time, anywhere, anytime with minimal equipment deployment and investment.

In this paper, Minimization of Flange effect and antenna transmit to receive isolation improvement using RF choke in Slotted Waveguide Array antenna is presented. In slotted waveguide antenna, the mounting of waveguide to the flight vehicle is done by using a waveguide flange. The flange causes variation in the antenna Radiation pattern, and increase in Side lobe level and thereby degrading the performance of antenna. An RF Choke adjacent to the waveguide wall, is used to nullify the undesirable effects of the flange. The comparison of simulated results with and without the flange and with and without choke are presented. It is observed that the quarter wave length groove called choke, at certain distance from waveguide wall, along the length of the waveguide improves the radiation pattern, isolation and SLL, hence reduces the flange effect. It is observed that the antenna properties of slotted waveguide antenna with flange and choke approximately matches with the antenna properties of slotted waveguide antenna without flange and choke. It is observed that presence of choke also improves the Isolation from transmit to receive antenna.

The purpose of the study was to analyze the basic technological process of manufacturing waveguide flanges at PJSC “ALMAZ R&P Corp.” LEMZ Division. A method for optimizing the process has been proposed, and a theoretical study using the finite element method has been carried out. The stress-strain state of the forging of a complex shaped flange during its manufacture with closed bulk forming has been analyzed as well.

The ITER Electron Cyclotron Heating Upper Launcher (ECHUL) will be used to drive current locally inside magnetic islands located at the q = 2 (or smaller) rational surfaces in order to stabilize neoclassical tearing modes (NTMs). Each of the fours antennas consists of eight beam lines, totaling 12.8 m that are designed for the transmission of up to 1.5 MW of mm-wave power at 170 GHz, with at least 90% of the power in the main HE11 mode. Each transmission line consists of a Z shaped set of straight corrugated, aluminum alloy waveguides connected by miter bends with a nominal inner diameter of 50 mm. The FCS system also encompasses intrinsic components such as: closure plate, mm-waveguide taper, isolation valve, diamond window and an EU-US interface waveguide. All FCS components are connected via a dedicated flange coupling, with a bolted connection, comprising of two concentric metallic seals in order to satisfy the SIC-1 requirements. The coupling shall be capable of resisting the applied external loads and displacements, including thermal cycles due to ohmic losses in the transmission line, and also adhere to the matting of different materials (EN AW-6082, CuCrZr, SS 316L) while maintaining ultra-high vacuum tightness (10 −8 mbar). The present study will use a dedicated experimental apparatus for the characterization of the mechanical and vacuum properties of a single metallic seal under compression, with applied heat flow. In order to ensure reproducibility of the components mechanical characteristics, randomly chosen metallic seals of each diameter have been tested from two independent manufactures (A and B).

Contact nonlinearity is one of the primary sources of passive intermodulation (PIM). Common methods to eliminate the contact nonlinearity are focused on improving the electrical contact. In this letter, the contactless waveguide flange (CWF) based on gap waveguide technology is first applied to solve the PIM problem caused by waveguide connection. A compact folded CWF is proposed for low-frequency applications. The artificial magnetic conductor plate, in the form of a bed of nails, is arranged surrounding the outer surface of the male flange, whereas a waveguide with broader hollow end serves as the female flange. The size of the proposed contactless flange is significantly reduced compared to its planer counterpart. An S-band prototype is designed, manufactured, and measured. Compared to traditional waveguide flange, the measured PIM level achieves a maximum improvement of 30 dB, which is almost unaffected by surface plating materials and connection pressure.

This paper presents a fully digital 390 GHz harmonic outphasing transmitter in a 28nm CMOS technology. The proposed architecture features the combination of phase predistortion and outphasing at the third harmonic enabling higher-order non constant envelope modulation schemes which is inherently difficult in multiplier-last architectures used in conventional THz data transmitters. The transmitter includes a 5-bit outphasing symbol generator at 15 GHz which can generate the necessary symbols for a variety of modulation schemes from OOK to STAR16 QAM. The transmitter is fully packaged with a micromachined waveguide flange such that it provides a standard waveguide output. It produces a peak output power of -16 dBm with a 3 dB IF bandwidth of 16.5 GHz and has a maximum measured datarate of 6 Gbps.

This paper reviews 300-GHz-band CMOS transmitter (TX) and receiver (RX) modules with a WR-3.4 waveguide interface that allows a high-gain antenna or some other component like an amplifier to be connected. A TX or RX chip fabricated using a 40-nm CMOS technology is mounted on a multilayer glass epoxy printed circuit board (PCB) by flip-chip bonding. A short section of on-board transmission line then leads to a waveguide transition with a back-short structure built into the PCB. The chip and the transition are completely covered by a WR-3.4 waveguide flange having a hollow for accommodating a chip and mounted onto the PCB. Wireless link between the TX and the RX modules achieves a data rate of 20 Gb/s with 16QAM over 10cm.

This paper presents a portable 3D-printed lens antenna fed by a standard rectangular waveguide at X-band for object classification. The proposed lens antenna can integrate with the standard rectangular waveguide without any additional assistant tools. A high impact polystyrene is used to design the 3D-printed hemispherical lens antenna by using the fused deposition modelling technique. This additive manufacturing gives several advantages including rapid prototyping, better cost and time effectiveness. Five lens radiuses, e.g., 20 mm, 30 mm, 40 mm, 50 mm, and 60 mm, are investigated to increase the gain of the antenna. The optimum dielectric tapered transition dimensions are simulated and obtained by using the 3D EM Simulation tool CST Studio, resulting in the reflection coefficient (S 11 ) of five lens antennas better than −10 dB across the WR-90 band. From the simulation results, the lens radiuses of 20 mm, 30 mm, 40 mm, 50 mm, and 60 mm, provide the average realized gain of 12.9 dBi, 15.2 dBi, 16.7 dBi, 17.7 dBi, and 18.6 dBi, respectively. To confirm the antenna performances of the proposed design, two lens radiuses, e.g., 20 mm and 30 mm are selected to fabricate. The gains of the lens radius of 20 mm and 30 mm are 12.1 dBi, and 14.2 dBi, respectively. The half-power beamwidth (HPBW) of lens radius of 20 mm and 30 mm are approximately 35° and 24°, respectively. The proposed dielectric lens antenna also offers other advantages, such as ease of design, low fabrication and material cost, and ease of mount and un-mount with WR-90 waveguide flange. Moreover, the narrow HPBW of lens antenna fed by standard waveguide can be applied to improve the resolution of the imaging system.

A new method of realising precision waveguide shims for use in THz Through-Reflect-Line (TRL) calibrations, based on silicon-micromachining, is introduced. The proposed calibration shims combine a thin λ/4 silicon layer, co-fabricated with a thicker layer which provides mechanical support. This design overcomes the limitations of CNC milling for the creation of calibration shims, facilitating use of standard TRL calibration at currently challenging frequencies. The novel shim fits inside the inner recess of a standard waveguide flange and is compatible with conventional flange alignment pins. Five micromachined shims were fabricated in a silicon-on-insulator process for operation in the WM-570 waveguide band (325–500GHz). The fabricated shims show excellent performance across the entire band, with return loss in excess of 25dB, insertion loss below 0.2 dB and high uniformity between samples. Verification reveals that the micromachined shims have an electrical length within 2% of the expected value. Comparative measurements of a DUT calibrated with the proposed shim and a previously un-used conventional metallic shim show that the novel concept offers equivalent, if not better, performance. The mechanical design of the micromachined shim and the rigid nature of silicon ensure that it will not suffer from performance degradation with repeated use, as is problematic with thin metallic shims. This work enables the creation of low-cost, highly-repeatable, traceable calibration shims with micrometer feature-sizes and high product uniformity, surpassing the limits of current techniques. QC 20190903. QC 20191219

This paper demonstrates planar designs of a microstrip-to-waveguide transition as well as a 4x1 patch antenna array at 79 GHz to investigate utilizing a new low-loss substrate material in radar applications. The planar transition enables direct surface-mounting of the standard waveguide flange without additional mechanical parts. It comprises of microstrip-to-substrate integrated waveguide (SIW) transition and SIW-WR12 transition. The patch antenna array is employed in a two-channel radar sensor where its radiation pattern is measured and verified.

A novel real-time rotatable rectangular waveguide twist is presented in this letter. The proposed waveguide twist is based on the contactless waveguide flange technique. The electromagnetic wave is confined inside the rectangular waveguide if the air gap between the two flanges does not exceed the maximum allowed distance. Therefore, relative rotation between the contactless flanges is allowed. Seven rectangular waveguide plates with smooth surface on one side of it but bed of nails on the other side are manufactured. They are stacked together layer by layer and are placed into a hollow circular housing. Two adjacent plates have a maximum twist angle of 15°. Therefore, the proposed stacked twist can realize any twist angle between 90°. A Ka-band prototype is designed, manufactured, and tested. The measured return loss is better than 15 dB, while the insertion loss is better than 0.3 dB over the whole Ka-band.

Contactless waveguide flange is a novel structure to prevent leakage of electromagnetic wave when it propagates across the waveguide flange. The main advantage of contactless waveguide flange is electrical contact of the connected waveguides is not required as long as the gap between the adjacent flanges does not exceed the maximum permitted distance. Therefore, relative motivation or rotation of the contactless connected waveguides is possible. The contactless waveguide flanges have been reported are all planar. A cylindrical contactless flange is first proposed. Then, a novel flexible rectangular waveguide is proposed based on it. A Ka-band prototype is successfully designed and manufactured. The prototype consists of two bendable contactless flange joints. The maximum bending angle of each joint is limited to ±8° to maintain the return loss performance. The number of joints can be easily increased if larger bending angles are needed. The insertion loss and return loss at different bending angles are measured. The measured insertion loss is better than 0.7 dB from 26 to 37 GHz, and is better than 1.8 dB from 37 to 40 GHz. The measured return loss is 15 dB except frequencies around 37.5 and 40 GHz.

Landmines still pose a serious threat mostly to civilians. Therefore, there is no doubt that working on the methods of landmines’ detection and liquidation should be considered extremely important. In this paper, we introduce the active infrared thermography with microwave excitation used in nonmetallic landmines’ detection. The effectiveness of the method is strongly dependent on the manner in which microwaves illuminate the ground. In this paper, we propose a new waveguide flange’s construction, which guarantees the uniform field distribution, and through this, a relatively uniform microwave heating on a certain area. The flange’s shape is based on box-horn. Its dimensions will be determined using a hybrid optimization algorithm. Results obtained in an optimization process will be validated using the numerical models. The experiments showing flange’s efficiency, concerning heating of sand itself and sand with buried landmines, will also be presented.

A wideband Ka-band waveguide-to-substrate integrated waveguide transition is presented based on a multi-section transformer approach. We designed our transition by successfully adapting multi-section inhomogeneous waveguide transformer theory to match a substrate integrated waveguide feedline to a standard waveguide flange, which offers more degrees of freedom than current design methods in the state of the art. We subjected our transition to a simulated tolerance analysis and have found the transition to be robust when fabrication errors are considered. We validated these simulations by measuring a back-to-back waveguide-to-substrate integrated waveguide transition, where there is very good agreement between measured and simulated results. Moreover, an insertion loss of −0.48 dB was measured at the center frequency of the required operating range. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:10–12, 2017

This paper presents a novel double-wing one-step 45° Gap waveguide twist at E-band. By employing an optimal double-wing structure for Gap waveguide flange, only one gap waveguide section is needed for the polarization transform between diagonal polarization and horizontal/vertical polarization, which does not require good conductive contacts between the connected flanges. This new waveguide twist is in particular useful and of low cost at millimeter wave frequency and up to THz.

Current waveguide flange standards do not allow for the accurate fitting of microchips, due to the large mechanical tolerances of the flange alignment pins and the brittle nature of Silicon, requiring greatly oversized alignment holes on the chip to fit worst-case fabrication tolerances, resulting in unacceptably large misalignment error for sub-THz frequencies. This paper presents, for the first time, a new method for directly aligning micromachined Silicon chips to standard, i.e. unmodified, waveguide flanges with alignment accuracy significantly better than the waveguide-flange fabrication tolerances, through the combination of a tightly-fitting circular and an elliptical alignment hole on the chip. A Monte Carlo analysis predicts the reduction of the mechanical assembly margin by a factor of 5.5 compared to conventional circular holes, reducing the potential chip misalignment from 46 μm to 8.5 μm for a probability of fitting of 99.5%. For experimental verification, micromachined waveguide chips using either conventional (oversized) circular or the proposed elliptical alignment holes were fabricated and measured. A reduction in the standard deviation of the reflection coefficient by a factor of up to 20 was experimentally observed from a total of 200 measurements with random chip placement, exceeding the expectations from the Monte Carlo analysis. To our knowledge, this paper presents the first solution for highly accurate assembly of micromachined waveguide chips to standard waveguide flanges, requiring no custom flanges or other tailor-made split blocks.

This paper presents the work carried out at LNE in order to establish the traceability of waveguide S parameter measurements to the International System of Units. The traceability is established through the dimensional measurement of the waveguide flange interfaces and the corresponding uncertainty component is evaluated against the standardized nominal values by using electromagnetic simulation and sensitivity analysis to dimension variations.

A novel simple approach to the verification process for millimeter-wave vector network analyzer waveguide cal- ibration is reported using a single reconfigurable component verification kit. Conventional techniques require multiple verifica- tion components and these only exist commercially for operation up to 110 GHz. At millimeter-wave frequencies, the use of multiple components can lead to significant errors due to imperfections in waveguide flange misalignments during the multiple component connections. The reconfigurable component is designed so that its electrical properties can be changed quickly to a broad range of predetermined values without introducing additional errors due to changes in flange alignment. Once connected, the component can be reconfigured to introduce relative changes in the reflected and transmitted signals. For millimeter-wave metrology, where mechanical precision is of paramount importance, this single-com- ponent verification approach represents an attractive solution. A proof-of-concept verification process is described, based on full-wave electromagnetic modeling, hardware implementation, and validation measurements using standard WR-15 waveguide (50-75 GHz).

Nondestructive evaluation of stratified (layered) composite structures at microwave and millimeter-wave frequencies is of great interest in many applications where simultaneous determination of the complex dielectric properties and thicknesses of multiple layers is desired. Open-ended rectangular waveguide probes, radiating into such structures, are effective tools for this purpose. The technique utilizes a full-wave electromagnetic model that accurately models the complex reflection coefficient as a function of frequency and material properties. While the electromagnetic model assumes an infinite waveguide flange (or ground plane), the measurements are conducted using a finite-sized flange. Consequently, the results of the electromagnetic model and those from measurements may not be sufficiently alike for accurate dielectric property and thickness evaluation. This paper investigates the effect of using an open-ended waveguide with a standard finite-sized flange on the error in evaluating the complex dielectric properties of a composite structure. Additionally, we present the design of a novel flange that markedly reduces this undesired effect by producing very similar electric field properties, at the flange aperture, to those created by an infinite flange. Finally, the efficacy of the design for evaluating the dielectric properties of a layered composite structure is demonstrated as well.

This paper presents techniques used to assemble and measure micromachined submillimeter-wave waveguide circuits operating from 500 to 750 GHz. A novel micromechanical compression pin is developed to improve wafer-to-wafer alignment to less than 1 μm. Connection between the silicon waveguide and the VNA is aligned through a silicon boss that inserts into the custom waveguide flange. Waveguide loss is characterized for both E- and H-plane split waveguides and is found to be similar to standard metal waveguides. Finally, measurement of a 3 dB hybrid coupler operating from 500 to 600 GHz is presented.

We have improved the measurement uncertainty for rectangular waveguide vector network analyzer (VNA) measurements in the WM-250 (WR 1.0), 750 GHz–1.1 THz frequency band. We developed a new waveguide flange design for precise connections and dimensional measurements to establish traceability to SI in VNA measurements. This is the first such achievement to be reported using a VNA in the terahertz frequency band.

This paper describes a computer vision based robotic waveguide flange alignment system that achieves improved repeatability of waveguide measurements. The proof-of-concept is demonstrated using WR-62 in the frequency band 12.40 GHz to 18 GHz. An Arduino board was used to interface a three-channel NTS NanoDirect XYZ positioner with MATLAB and its image acquisition toolbox. The measured results of a back-to-back adapter pair demonstrate significantly improved repeatability with the automated system compared with manual alignment. Through EM modelling of two WR-1.0 rectangular waveguides over the frequency range 800 GHz to 1 THz it is shown that this new method for enhancing measurement repeatability will be invaluable.

Connection torque of waveguide flange is one of major impact factor of measurement reproducibility in the range of millimeter-wave and terahertz frequencies. Generally, connection of waveguide flange is made by four screws specified in the MIL-DTL-3922/67C (UG-387). However, different values of connection torques are specified and used in the each society and industry. There is no existing specification for connection torque. In addition, the four screws connection have to spend time to make a connection/disconnection for waveguide flange, then the measurement stability for long time was concerned due to stability performance of vector network analyzer frequency extension module. The new connection clamp for waveguide flange has been proposed as a solution to make connection quickly[1]. This paper investigate a connection feature and its torque value to make good connection repeatability.

Heterodyne and direct detection radiometer receivers at 94 GHz have been realized in a 130 nm Si/SiGe BiCMOS process. They have been assembled into fully self-contained metal housings with a waveguide flange for the antenna connection. The receivers, which employ a SiGe LNA with below 4 dB noise figure, show overall responsivities of 620 µV/K and 380 µV/K respectively.

Measurements with waveguide flanges at frequencies above 100GHz have a considerable issue with leakage due to problems with achieving good electrical contact between the opposite flanges. The higher the frequency, the higher is the requirement for full contact. However, by using an artificial magnetic conducting (AMC) flange on one side of the interface, full electric contact is not needed between the two joining flanges. The AMC is realized as a pin-surface, and the leakage is stopped by a parallel-plate stopband like in gap waveguides. This paper describes how these AMC pin waveguide flanges can be used for screw redundant measurements.

In this paper, we demonstrate a packaged sub-millimeter wave solid-state power amplifier (SSPA). The SSPA is implemented in coplanar waveguide (CPW) and uses an advanced high fMAX InP HEMT transistor with a sub 50-nm gate. A monolithically integrated CPW dipole-to-waveguide transition eliminates the need for wirebonding and additional substrates. On-chip compact tandem couplers are used for power combining. The amplifier demonstrates 15-dB small-signal gain at 340 GHz. Peak saturated output power of 10 mW at 338 GHz is obtained at the waveguide flange out-put for the SSPA module.

This letter presents two different waveguide-to-microstrip transition designs for the 76-81 GHz frequency band. Both transitions are fabricated on a grounded single layer substrate using a standard printed circuit board (PCB) fabrication process. A coplanar patch antenna and a feed technique at the non-radiating edge are used for the impedance transformation. In the first design, a conventional WR-10 waveguide is connected. In the second design, a WR-10 waveguide flange with an additional inductive waveguide iris is employed to improve the bandwidth. Both designs were developed for the integration of multi-channel array systems allowing an element spacing of λ0/2 or less. Measurement results of the first transition without the iris show a bandwidth of 8.5 GHz (11%) for 10 dB return loss and a minimum insertion loss (IL) of 0.35 dB. The transition using the iris increases the bandwidth to 12 GHz (15%) for 10 dB return loss and shows a minimum insertion loss of 0.6 dB at 77 GHz.

[EN] In this paper, the generation of passive intermodulation at rectangular waveguide flange bolted connections is investigated. An exhaustive series of tests has been performed in order to provide understanding on the physics lying behind such a phenomenon. In particular, the intermodulation response of the system has been studied as a function of the applied torque to the flange screws. It has been found that, in some situations, the intermodulation response differs from its expected behavior. An interpretation of such discrepancies is given, and practical guidelines for the design of waveguide flanges free of passive intermodulation are provided as well., This work was supported by the European Space Agency under the Surface Treatment and Coating for the Reduction of Multipactor and Passive Intermodulation Effects in RF Components Project, by the European Space Research and Technology Centre under Contract 17025/03/NL/EC, by the Generalitat Valenciana (Spain) under PREDECTOR Project IIARC0/2004/020, and by the Spanish Government (MEC) under a Juan de la Cierva Program Fellowship.

Apractical problem in the reflection method for dielectric constant measurement is the difficulty to ensure the sample is placed exactly at the waveguide flange. Asmall position offset of the dielectric sample will give rise to some errors in calculating the dielectric constant, especially when a thin sample is used. To circumvent this problem, a method to determine the dielectric constant by measuring the transmission coefficient of the thin slab placed in a waveguide has been developed. Slab position offset from the measurement reference plane has no effect on the measurement accuracy. An explicit expression for the dielectric constant is obtained in terms of the transmission coefficient by simplifying the exact solution for transmission through a thin dielectric slab. The method is verified with measurement on Teflon of 0.5-mm thickness. The measured dielectric constant of Teflon shows excellent agreement of both e � and e �� with published data. Subsequently, the dielectric constant of a vegetation

A photonic choke joint structure with a wide- stop-band is proposed for use as a waveguide flange interface. The structure consists of arrays of square metal pillars arranged in a periodic pattern to suppress the dominant-mode wave propagation in parallel-plate waveguide over a wide frequency bandwidth. The measurement results at microwave frequencies confirm the structure can provide broadband suppression, more than 56 dB over 6.25 times its operating frequency. Applications at millimeter wavelength are discussed.

A new reflectometer calibration method is described that utilizes four standards: a flush short, two delay shorts with unspecified but different phases, and an open-ended waveguide. The calibration method eliminates the requirement for a precision waveguide matched load, which can be problematic to realize at submillimeter wavelengths. Importantly, it is shown that the technique is resistant to waveguide flange misalignment, which is among the most serious factors that degrade the calibration accuracy of vector network analyzers operating above 100 GHz. Scaled measurements using this method have been performed in the W-band (75-110 GHz) where it is readily compared to other calibration methods such as thru reflect line to assess its utility and performance. Measurement results demonstrate the robustness of this new calibration method and have verified it is superior to the commonly utilized short/delayed-short/load technique with respect to the influence of waveguide flange misalignment

A practical problem in the reflection method for measuring permittivity of thin materials is the difficulty in ensuring the sample is placed exactly at the waveguide flange. A small position offset of the dielectric slab will give rise to significant errors in calculating the permittivity. To circumvent this problem, a measurement method using a waveguide partially filled with a thin material slab has been developed. The material sample can be easily prepared and inserted into the guide through a longitudinal slot on the broad wall of the waveguide. Multiple material slabs can be measured rapidly because one does not have to disconnect the waveguide system for sample placement. The method is verified with measurement of Teflon, glass and FR4 fibreglass. The measured permittivity show good agreement with published data. Subsequently, the permittivity of a vegetation leaf was measured. The method presented in this paper is particularly useful in measuring the permittivity of a thin and narrow slab of natural materials such as a paddy leaf.

Condensed moisture from ingressed humid air was responsible for inducing corrosion within the aft radar antenna from an RAAF P-3C Orion maritime surveillance aircraft. Porosity in the silver-plating of a flexible brass waveguide allowed moisture to penetrate to the brass substrate and cause dezincification. The moisture also induced corrosion of some of the AA-6061 aluminium alloy waveguides. An investigation determined that moisture ingress occurred at a waveguide flange, possibly from the failure of a seal.

A bandpass, miniaturized-element frequency selective surface with relatively high out-band rejection was recently reported whose unit cell dimensions are smaller than lambda 0 /10. The new FSS is made up of a metallic, square loop array and a metallic grid on either side of a thin dielectric substrate. Further analysis on this structure reveals that, a very wide frequency tuning can be accomplished by inserting lumped, variable capacitors in the gap between the loops. This paper presents the tunability performance of the miniaturized-element FSS. For experimental verification, a waveguide measurement approach is chosen to lower the fabrication cost. The FSS unit cell dimensions are modified appropriately to fit within a WR90 waveguide aperture and appear as a perfect periodic surface once image theory is applied. Prototypes of the structure in the form of a waveguide flange at X-band are fabricated and then loaded with fixed-valued, chip capacitors of different values. Each waveguide sample contains eighteen capacitors mounted on it. The measurement results show that a wide tuning range, with acceptable performance, from 8.49 to 11.48 GHz can be accomplished by altering the capacitance from 0.2 to 0.05 pF.