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In this article, a tunable ferrite-loaded isolator working at millimeter-wave (mm-Wave) frequency for applications in multi-function systems is presented. The device is based on nonreciprocal coupling between a ferrite slab and a half-mode substrate-integrated waveguide (HMSIW). The HMSIW offers a compact design and, more important here, the ability of energy coupling to adjacent resonators. The ferrite slab is placed outside the HMSIW, close to the H-wall symmetry of the HMSIW, providing the possibility of movement for the ferrite slab and low insertion loss of the transmission mode. Any change in the position of the ferrite slab changes the propagation constant of the mode traveling across the ferrite-coupled HMSIW, which, consequently, results in different center frequencies of the isolation. To the best of our knowledge, the proposed design is one of the first tunable isolators for such a high frequency. Despite previously reported isolators that require a strong magnetic bias field for mm-Wave range applications, the proposed isolator requires a relatively low magnetic bias (less than 20 KA/m), which is provided by a small and lightweight permanent magnet. The 10 dB isolation bandwidth of the design is about 2 GHz varying from 34 to 37 GHz based on the position of the ferrite slab. The insertion loss of the device is measured between 2 and 3 dB. [ABSTRACT FROM AUTHOR]

In this communication, a dual-band on-chip meander-line monopole antenna is proposed and demonstrated for emerging fifth-generation (5G)-compatible Internet of Things (IoT)-served sensor nodes. The targeted 28/60 GHz compact antenna is a hybrid structure of meander-line monopole antenna and packaging substrate to both shield the antenna from its deployed environment and to enhance the antenna radiation efficiency as well as the gain over the two bands of interest. The antenna model and design analysis are presented in this work together with a fabricated and tested 65 nm bulk CMOS chip. The prototyped on-chip antenna exhibits a measured gain of −10 dBi at 28 GHz with a bandwidth of 5.3% and 0 dBi at 60 GHz with a bandwidth of 5.9%. A radiation efficiency of 45% and 30% is obtained at 28 and 60 GHz, respectively. The antenna occupies a space of 0.25 × 0.3 mm2 (λ/43 × λ/35.7 at 28 GHz). The on-chip antenna solution proposed in this work addresses the highly desirable yet challenging overall design of future wireless systems (5G and beyond) which hit the mark on compactness, cost, and compatibility. In addition, this work provides a viable design platform for achieving frequency diversity and multifunctionality of future wireless involving power harvesting, data transfer, and sensing operation. [ABSTRACT FROM AUTHOR]

In this article, the oversized substrate-integrated waveguide (OS-SIW) is proposed, analyzed, and experimentally demonstrated. The physical parameters and the effect of material surface roughness on the attenuation and the SIW power capability lead to the exploitation of wider and thicker waveguides, as an alternative to enhance the power-handling capability (PHC) and reduce the losses. The resulting oversized waveguide is a guide whose width or thickness is greater than that of the SIW, which is sized to support only the TE10 mode in the operating band. An SIW-to-OS-SIW transition has been designed to allow the component characterization in the W-band. The proposed transition allows to propagate only the desired mode TE10 in the OS-SIW and prevent the higher mode propagation. The experimental results of the manufactured prototypes accord well with the simulations in terms of power handling and transmission losses. The proposed OS-SIW line shows lower attenuation (1.5 Np/m) than a standard SIW (3 Np/m) or a microstrip line (about 3.7 Np/m). However, the OS-SIW 5a has achieved an average power of 90 W at 90 GHz. The investigated OS-SIW configuration offers high PHC, low losses, and easy integration into high-power millimeter-wave systems. [ABSTRACT FROM AUTHOR]

A harmonically driven bio-radar based on the technique of a multiport interferometer (six-port) technique is proposed and studied in order to improve the performance of vital signs monitoring. The feasibility of estimating cardiopulmonary parametric signatures by deploying a harmonic multiport interferometer radar is presented. This scheme is helpful to reduce the noise floor and the effects of undesirable parasitic harmonics of breathing and intermodulation. A theoretical analysis is developed to explain why a better heart-beat detection using the proposed harmonic six-port radar architecture can be achieved. The well-known null point problem usually encountered in such radar detections of heart-beating signs is alleviated by the insertion of a fixed 45° phase shift between the two different frequencies in the six-port discriminator without an actual phase-shifter. Simulations are carried out to investigate detection accuracy and sensitivity issues for monitoring the vital signs by cancelling the breathing harmonics and intermodulation products. The concept is then validated by the measured results of an experimental prototype using the proposed harmonic six-port radar platform operating at 12 GHz (fundamental) and 24 GHz (harmonic). [ABSTRACT FROM AUTHOR]

This paper presents a spatially distributed multi-input direct conversion receiver architecture based on interferometric correlations of wave signals for fifth generation systems and beyond. The proposed receiver scheme inherits the advantages of conventional six-port receivers. The spatially distributed multi-input architecture is based on the use of a set of equally spaced four antenna elements instead of using a six-port junction composed of four hybrid couplers or other alternative circuit-based topologies. In this paper, the mathematical modeling of the proposed receiver is derived and presented. Then, an experimental test bench that is fabricated to operate around 5 GHz is introduced in order to validate the proposed scheme and its theoretical results. Various modulations including BPSK, QPSK, QAM-16, and QAM-32 have been successfully studied and demonstrated by this receiver at a relatively low date rate of 1 mega symbol per second with a maximum error vector magnitude of 10.3%. The maximum bit rate is fundamentally limited by the speed of power detectors, which is linked to their high rise time in our experiments. It is anticipated that multiple hundred megabits and gigabits per second can be achieved with the proposed direct conversion receiver if higher speed power detectors are used. [ABSTRACT FROM AUTHOR]

The recently developed mode-selective transmission line (MSTL) is proposed and exploited as an alternative approach to accommodate the growing and future ultrafast interconnects requirements of ultralarge-scale integration for high density, speed, performance, and bandwidth (BW). A parametric study is performed to optimize the MSTL structure for high-speed global interconnects and to provide high-performance signal integrity. Picosecond and rectangular pulse propagations on MSTL are examined, and pulse distortion, broadening, ringing, and reflection are characterized. An eye diagram is also shown to examine the jitter and noise. Due to our limited low-cost printed circuit board (PCB) fabrication accuracy, the frequency-domain measurement is carried out up to 110 GHz. Our optimal fabricated MSTL structures show an ultrawide absolute BW covering dc, maintain more than 200% relative BW while transmitting around 90° bends, and achieve a measured crosstalk of better than −45 dB over the entire band. Time-domain characterizations imply that the PCB-based MSTL accommodates data rates greater than 200 Gb/s. This technology allows, for the first time, the transmission of ultrahigh-speed electrical signal and picosecond pulse transmission through global interconnects with much lower dispersion and loss than today’s technologies. [ABSTRACT FROM AUTHOR]

Abstract: A planar waveguide and a rounded bend is proposed, designed, and implemented through a hybrid structure of substrate integrated waveguide (SIW) and electromagnetic bandgap (EBG) material. In order to design the EBG waveguide, a square lattice of air holes situated between two metal plates is used. The SIW line and bend are inserted on EBG waveguide to enhance performance. These devices were fabricated and measured. The experimental results show a homogeneous agreement with the simulation. The combination EBG‐SIW covers almost the whole EBG bandwidth of 6 GHz (17%) around 35 GHz. The proposed hybrid integration technique presents a competitive candidate for the development of millimeter‐wave circuits and systems. [ABSTRACT FROM AUTHOR]

In this paper, an on-chip dual-band rectangular slot antenna is proposed and demonstrated for a new generation of high data rate, battery free, yet active millimeter-wave identification (MMID) system, which is fully integrated on a single-CMOS die. It, therefore, does not require any external components (padless) nor the traditional packaging. The single-antenna solution proposed in this paper addresses the overall system compactness, the cost, and the underlying technical challenges related to multifrequency reader-tag MMID system, such as the alignment between the reader’s and tag’s antennas (accurate line-of-sight, especially in a short-range communication system). The targeted 24/40-GHz compact antenna is a hybrid structure of a dielectric resonator antenna (DRA) and a coplanar waveguide-fed rectangular slot antenna in order to facilitate interconnections with other integrated circuit blocks. Design analyses of the antenna are presented. Dual dielectric resonator is optimized to enhance the antenna radiation efficiency as well as the gain over the two bands. Using a 65-nm-bulk CMOS process, a chip was fabricated and tested. The prototyped antenna exhibits a measured gain of −1 dBi at 24 GHz with a bandwidth of 19%, 0 dBi at 40 GHz with a bandwidth of 20%, and a radiation efficiency of 41% and 31%, at 24 and 40 GHz, respectively. The antenna occupies a compact size of $2.5\times 2.5\times2.5$ mm3 with DRA. [ABSTRACT FROM PUBLISHER]

A systematic scheme for finding the direction of arrival (DOA) or 2-D angle of arrival (AOA) of an electromagnetic beam is proposed and demonstrated in this paper. This system estimates the respective angle of propagation vector of an incoming plane wave in either horizontal or vertical plane. It consists of three main parts, namely, an antenna, a multiport wave interferometric receiver or phase discriminator, and a signal processor. The antenna is composed of four receiving elements located in the same plane, which is arranged in a diamond-shaped configuration. The received signals manifest relative phase differences that contain information about the beam’s DOA. With the proposed eight-port junction topology, the interferometer extracts these informative phase differences and leaves them for a simple signal processing algorithm to estimate the two angles. The theoretical analysis of the proposed scheme is presented along with system-level simulation results for the proof of concept. In addition, an appropriate calibration technique is formulated to deal with nonidealities and consecutive errors in practice. One of the main applications of such a system is related to the angular detection of an antenna-to-antenna misalignment in pencil beam millimeter-wave systems. Therefore, implementation of the presented system scheme for millimeter wave applications is briefly discussed for its prototyping over 60-GHz range (V-band). Finally, the performance of the prototype system is assessed through a set of system-level measurements. Excellent results are obtained, thus validating the outstanding functionality of the proposed system. Simplicity, low cost, compact size, and operational accuracy make this system a superior candidate for 2-D angle detection applications. [ABSTRACT FROM AUTHOR]

In this paper, a unified method is introduced and formulated for deriving the equivalent circuit model of a guided wave structure as well as its characteristic impedance for any mode. This method is developed through the combination of a generalized multimode calibration and a full-wave simulation, and it is applicable to the fundamental mode as well as higher order modes. The method is verified for both TEM and non-TEM propagating modes and is applied to extract the characteristic impedance and circuit model of non-TEM guided-wave structures. This scheme allows for the effective use of a commercial electromagnetic field simulator in removing inherent numerical simulation noises or errors. Extracting circuit parameters through this technique for establishing equivalent circuit models can overcome the shortcomings encountered in the modeling of guided-wave eigenvalue problems as well as in the design of multimode structures. [ABSTRACT FROM PUBLISHER]

In this paper, a class of high-data-rate battery-free yet active miniature radio-frequency identification tag without any external components (except antenna) operating at millimeter (mm)-wave frequencies is proposed and demonstrated. This fully embedded tag consists of a recently proposed CMOS-based zero-intermediate-frequency self-oscillating mixer, a high power conversion efficiency mm-wave-to-dc rectifier, and an ultralow-power voltage regulator on a single chip, integrated with ceramic-based antennas. Interconnection between the CMOS die and the antenna is realized using a wire-bonding technique, which is compensated and optimized to match the antenna input impedance and also to minimize the wire-bond associated losses at mm frequencies. The $10 \times 10$ mm2 tag wirelessly harvests its energy from an incoming signal at 24 GHz, receives, and recovers the data sent by reader on an amplitude modulation (AM)-modulated 40-GHz carrier, and transmits its data back to the reader on a 40-GHz carrier, using AM modulation as well. The tag exhibits a bit rate of about 500 kb/s during the reader-to-tag communication and 10 Mb/s during the tag-to-reader communication, solely relying on the rectified energy for powering its operation. To the best of our knowledge, such an mm-wave identification tag at mm-wave frequencies has never been reported in the literature. [ABSTRACT FROM PUBLISHER]

The microstrip patch antenna (MPA) with frequency stability versus temperature is proposed as the ice sensor for de-icing of aerodynamic systems. The operation principle is based on the fact that the formation of ice layer is set to disturb the near fields, thus shifting the resonant frequency. To mitigate the uncertain temperature effect, a thermal stability (TS) strategy is implemented, making the sensor only susceptible to the ice loading effect and enabling stable performance within a large temperature range from − 40∘C to + 80∘C. The proposed ice sensor is in turn interrogated wirelessly by a transmitting (Tx) antenna. Due to the frequency shift, the received signal strength (RSS) is modulated as a function of ice-thickness, allowing for remote ice detection and quantification. Two common types of ices, namely rime and clear ices, are investigated. The ice samples were generated and characterized under different weather conditions in our cold chamber and wind tunnel at Anti-icing Materials International Laboratory (AMIL) with the University of Quebec at Chicoutimi (UQAC). Experimental results show the feasibility of the proposed approach for different real-world scenarios. In particular, the sensor demonstrates the best measurement capability in the case of clear ice with full coverage, achieving the sensitivity of 75 mV/mm. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper presents an on-wafer millimeter-wave circuit’s characterization build on thin ceramic substrate having a high relative permittivity. An RF short circuit, designed with a quarter-wavelength radial stub, is used in load design and launch transition. To improve the design accuracy of electromagnetic (EM) tools, the dielectric constant of the ceramic substrate is extracted using measurements of several pairs of microstrip lines combined with EM simulations. The largest deviation obtained, compared with the mean value over the frequency band, is less than 1%. Thus, a new six-port circuit is designed and characterized using a millimeter-wave probe station. A comparison between the measurement and simulation results, using extracted manufacturer-recommended relative permittivity, is conducted. The six-port qi points’ location is close to the simulated and theoretical ones over the frequency band of interest. As demonstrated in this paper, the substrate permittivity extraction has improved the design accuracy of the millimeter-wave circuits. Excellent performance of this circuit in terms of matching, isolation, and amplitude and phase balance is obtained. [ABSTRACT FROM AUTHOR]

A class of directional couplers based on the substrate integrated waveguide (SIW) technique for compact three-dimensional (3-D) integrated circuits is proposed and studied in this work. Backward and forward couplers as well as strong coupling-defined forward couplers are presented and developed. They are composed of two joined SIW sections such that the common wall between them is made of a portion of the broad side of the first SIW and the narrow side of the second SIW. This perpendicular topology is arranged and formed through the use of a LEGO-like interconnect between the two SIW structures. Different coupling geometries developed with a low-cost printed circuit board process are studied. Design considerations and measured results at Ka-band are presented and discussed. To achieve respectively weak backward and forward directional couplings, Schwinger and multihole-type directional couplers are introduced first of all, which make use of coupling slots arranged around the center of the SIW broad wall. For each of those structures, a wideband 20-dB directional coupler is fabricated and measured for demonstration purposes. To achieve a strong coupling, a Riblet-type directional coupler is proposed and examined. Subsequently, a 3-dB coupler is demonstrated together with a 0-dB coupler, offering a wideband and very efficient transition between the perpendicularly arranged SIWs. The proposed directional couplers can be used at millimeter-wave frequencies for probing and the design of compact 3-D integrated circuits and systems such as polarimetric imaging radiometer or antenna array feeding networks. [ABSTRACT FROM PUBLISHER]

This study presents a compact circularly polarised array using tapered slot antenna fed by a substrate integrated waveguide (SIW) power divider. With the proposed topology, broadband circularly polarised property is achieved and total gain can be increased by controlling the element length, conserving the same footprint area. The different 2 × 2 cell configurations are investigated. Simple and integrated series-parallel SIW feed for the choose cell is presented. A 2 × 2 antenna array is designed and fabricated using SIW E-plane power divider. The measured 10 dB return loss and 3 dB axial ratio bandwidths are 35.65 and 32.3%, respectively. The measured antenna gain is 14.4 dBi at 35 GHz. [ABSTRACT FROM AUTHOR]

This paper proposes and presents a class of substrate integrated waveguide (SIW) power dividers/combiners based on a modified Wilkinson architecture. The proposed design consists of a ring-type circuit of \(1.5~\lambda _{g}\) length with three waveguide ports. Impedance variation without affecting cutoff frequency and integration of isolation resistance are the two major limitations in connection with the design of SIW Wilkinson structures. Central ring part with different thickness ensures different impedance in the first proposed scheme while the half-mode SIW in the second option. As for the second limitation, the optimal configuration of integrating the isolation resistance is studied. A version without resistance is also examined using a broad-wall series slot. To validate the proposed concept, a bilayered circuit with standard Printed circuit board prototype was fabricated and measured. A table summarizing performances of all the proposed circuits shows a bandwidth of around 25% at the 10 dB reference. A negligible additional insertion loss is observed. The proposed design techniques are found useful at millimeter-wave frequencies where reduced physical dimensions make a circuit configuration suitable for low-cost implementation. This concept is also valid for rectangular waveguide counterparts. [ABSTRACT FROM AUTHOR]

A Butler matrix-fed two-dimensional (2-D) scan linearly polarized 2 \times 2 microstrip ring antenna array (MRAA) is proposed and validated in low-cost substrate integrated waveguide (SIW) technology for Ka-band applications. The highly efficient, compact, and passive beam forming network (BFN) consists of SIW cruciform couplers as coupling unit, and its special topology is well adapted for feeding planar arrays. The wideband and high radiation efficiency antenna elements are aperture-coupled through slots etched on the top of a high permittivity SIW feed substrate. Such four antenna elements are used to construct 2 ~\times 2 MRAA and to form four fixed beams, one in each quadrant at an elevation angle of 20^\circ from the broad side array axis. A triangular grid arrangement is chosen to avoid grating lobes in the visible space. A 50-\Omega grounded coplanar waveguide (GCPW) to SIW transition is used to avoid spurious input feed radiation loss. The array is measured to exhibit 3-dB beam width of 30^\circ in both of the orthogonal planes, radiation efficiency of 70% for each port, and stable radiation pattern bandwidth of 7.6% at 26.5 GHz. The physical size of the demonstrated 2 \times 2 array is 2.86\lambdao\times 2.86\lambdao\times 0.22\lambdao. [ABSTRACT FROM PUBLISHER]

In this paper, a substrate integrated waveguide power divider is proposed on the basis of a recombinant topology that provides in-phase power division with an odd or even number of branches. The aim is to generate different types of power distribution to control sidelobe level in the antenna array. In this study, several power-divider designs were designed to demonstrate and validate the design approach. Each design consists of a cascade of steps and nfurcations, which were initially designed based on sinusoidal basis functions. These designs were simulated using the High Frequency Structure Simulator (HFSS) and shown to closely match the performance estimated using the basis functions. A substrate with thickness of 0.508 mm and dielectric constant of 2.94 is used. A three-way power divider with a binominal output taper is optimized and fabricated, showing good results in the bandwidth of interest from 72 to 81 GHz. Measurement results for a 3 \times 8 slot array antenna designed in conjunction with the proposed feeding network are presented and discussed. This design can be used to build up rectangular waveguide structures. The novel structure is expected to be useful in building sub-arrays of antenna in the development of millimeter-wave automotive radar systems. [ABSTRACT FROM PUBLISHER]

A class of three-dimensional planar arrays in substrate integrated waveguide (SIW) technology is proposed, designed and demonstrated with 8 \times 16 elements at 35 GHz for millimeter-wave imaging radar system applications. Endfire element is generally chosen to ensure initial high gain and broadband characteristics for the array. Fermi-TSA (tapered slot antenna) structure is used as element to reduce the beamwidth. Corrugation is introduced to reduce the resulting antenna physical width without degradation of performance. The achieved measured gain in our demonstration is about 18.4 dBi. A taper shaped air gap in the center is created to reduce the coupling between two adjacent elements. An SIW H-to-E-plane vertical interconnect is proposed in this three-dimensional architecture and optimized to connect eight 1 \times 16 planar array sheets to the 1 \times 8 final network. The overall architecture is exclusively fabricated by the conventional PCB process. Thus, the developed SIW feeder leads to a significant reduction in both weight and cost, compared to the metallic waveguide-based counterpart. A complete antenna structure is designed and fabricated. The planar array ensures a gain of 27 dBi with low SLL of 26 dB and beamwidth as narrow as 5.15 degrees in the E-plane and 6.20 degrees in the 45^\circ-plane. [ABSTRACT FROM PUBLISHER]

This communication presents a low-cost 77-GHz switched-beam slot antenna array driven by a Butler matrix. In the proposed configuration, four broadband couplers are combined and crossovers are effectively avoided. In this case, the overall circuit and beamforming network losses are considerably reduced. A 4\,\times\,4 planar SIW Butler matrix is designed and demonstrated for integrated beamforming network applications, which exhibits about 7 degrees phase error and \pm 0.75~dB coupling imbalance over 11% bandwidth. This experimentally prototyped matrix is integrated with a four-array slot antenna on the same substrate. An alternating displacement of the slots in subsequent radiating waveguides is proposed to save the arrangement of the input ports and to achieve broadband performances. Measured radiation patterns are in good agreement with simulated counterparts over the proposed 77-GHz frequency range. [ABSTRACT FROM PUBLISHER]

This paper presents and demonstrates a class of 3-D integration platforms of substrate-integrated waveguide (SIW). The proposed right angle E-plane corner based on SIW technology enables the implementation of various 3-D architectures of planar circuits with the printed circuit board and other similar processes. This design scheme brings up attractive advantages in terms of cost, flexibility, and integration. Two circuit prototypes with both 0- and 45^\circ vertical rotated arms are demonstrated. The straight version of the prototypes shows 0.5 dB of insertion loss from 30 to 40 GHz, while the rotated version gives 0.7 dB over the same frequency range. With this H-to-E-plane interconnect, a T-junction is studied and designed. Simulated results show 20-dB return loss over 19.25% of bandwidth. Measured results suggest an excellent performance within the experimental frequency range of 32–37.4 GHz, with 10-dB return loss and less than \pm4^\circ phase imbalance. An optimized wideband magic-T structure is demonstrated and fabricated. Both simulated and measured results show a very promising performance with very good isolation and power equality. With two 45^\circ vertical rotated arm bends, two antennas are used to build up a dual polarization system. An isolation of 20 dB is shown over 32–40 GHz and the radiation patterns of the antenna are also given. [ABSTRACT FROM PUBLISHER]

A new temperature compensation method is proposed and demonstrated in this paper for cavities and filters realized in substrate integrated waveguide (SIW). The SIW structures largely preserve the well-known advantages of conventional rectangular waveguide, namely, high Q and high power capacity, and have the advantages of microstrip lines, such as low profile, small volume, and light weight. In this paper, we demonstrate that by an adequate selection of substrate properties, SIW cavities can provide self-temperature drift compensation. The compensation is achieved by using an appropriate ratio between the coefficient of thermal expansion and the thermal coefficient of the permittivity. The theoretical prediction is confirmed by an experimental investigation using inductive post filters. Three commercially available substrates are used to design cavities at 10 GHz with the Roger TMM10 substrate providing a close fit to the required characteristics for temperature compensation. The results for the cavity show a stability of 2 ppm/^\circC in calculation and 8 ppm/^\circC in measurement. A SIW fourth-order Chebyshev filter, centered at 10 GHz with 1-GHz bandwidth, has also been designed. The measured frequency drift is 9.1 ppm/^\circC and the bandwidth variation is \pm \0.13\\% over the temperature range of -\40\ ^\circC to +\80\ ^\circC. [ABSTRACT FROM AUTHOR]

In this article, a multilayered substrate integrated waveguide (SIW) Butler matrix beam-forming network is proposed, designed, and demonstrated at 24 GHz for automotive radar system applications. The proposed low-cost SIW structure can be used to develop a highly integrated multibeam antenna platform in automotive radar systems and other applications. In this structure, an SIW H-plane coupler is optimized with an H-plane slit to provide the required phase shift. A class of SIW E-plane 3-dB couplers in doubled layer substrate are studied and designed as the fundamental building blocks to avoid crossovers usually required in the construction of a Butler matrix. A 4 × 4 matrix is investigated and designed, which shows excellent performance over 22-26 GHz frequency band. Two types of antenna are tested with the proposed matrix scheme. First, an antipodal linearly tapered slot antenna (ALTSA) is incorporated into the Butler matrix to verify the broadband performances. Second, a longitudinal slotted waveguide antenna array is examined to generate radiation patterns in the broadside direction. Measured results agree well with simulated counterparts, thus validating the proposed multilayer SIW design concepts. In the next sections, the use as feeding networks for providing the reconfigurability operation of an antenna will be illustrated. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2012. [ABSTRACT FROM AUTHOR]

Millimeter wave applications such as short-range high-speed wireless links require modular, compact-size and high-directivity antennas. In this paper, high-gain compact stacked multilayered Yagi designs are proposed and demonstrated in the V-band. This novel design shows for the first time an antenna array of Yagi elements in millimeter wave stacked structure. To demonstrate the proposed concepts and design features, a 4\,\times\,4 antenna array is created having excellent gain performance as well as very small footprint. A single element stacked Yagi antenna fed with microstrip is studied in order to obtain the desired performance. An analysis is performed to define the structure limitations. Measured results of the fabricated antenna prototypes are in good agreement with simulated results The measured Yagi antenna attains 11 dBi gain over 4.2% bandwidth with a size of 6.5\,\times\,6.5\,\times\,3.4 mm^3. A 4\,\times\,4 array of Yagi antenna using an SIW (Substrate Integrated Waveguide) feeding technique is conceived. Both simulated and measured results match with each other very well. The 4\,\times\,4 array has a size of 28\,\times\,24\,\times\,2.4 mm^3, and reaches a measured gain of 18 dBi over 7% bandwidth. An alternate configuration of the array using angled Yagi antenna elements allows a significant improvement of the side lobe level (SLL) with a low impact on the gain performances. The proposed antennas are excellent candidates for integrated low-cost millimeter-wave and even terahertz systems. The small foot print, the antenna design flexibility as well as its easy adaptation to automatic fabrication processes are good assets for making short range portable imaging systems. [ABSTRACT FROM AUTHOR]

A broadband Nolen matrix in substrate integrated waveguide (SIW) technology is proposed and studied in this paper. Being serial feeding networks, Nolen matrices usually introduce significant phase dispersion in their standard form, thus limiting effective bandwidth. In this work, broadband frequency operation is achieved with adequate coupler delay compensation, resulting in a more “parallel” matrix topology. Consequently, H-plane couplers with continuous aperture are preferred in the proposed design as opposed to the cross-couplers previously used in the “serial” configuration. The SIW couplers and phase shifters of a balanced amplitude 4\,\times\,4 Nolen matrix are designed at 77 GHz for radar applications. The resulting matrix that combines these elementary building blocks is fabricated and measured, and measured characteristics are in good agreement with theoretical and simulated predictions. This first design achieves excellent results over a 11.7% frequency bandwidth centered at 77 GHz. This modified Nolen matrix combines advantages of standard Nolen and Butler matrices and may be used as a building block for generalized orthogonal matrices. [ABSTRACT FROM PUBLISHER]

There are many applications such as local positioning systems (LPS) and wireless sensor networks that require high-directivity and compact-size or small footprint antennas. The classical Yagi-Uda antenna may be useful in meeting such demands, which however, becomes very large in size to achieve a high-gain performance due to a large number of directors as well as space required between those elements. In this paper, high-gain yet compact stacked multilayered Yagi antennas are proposed and demonstrated at 5.8 GHz for LPS applications. This structure makes use of vertically stacked Yagi-like parasitic director elements that allow easily obtaining a simulated gain of 12 dB. Two different antenna configurations are presented, one based on dipole geometry for single polarization, and the other on a circular patch to achieve dual polarization. The characteristics of these antennas with respect to various geometrical parameters are studied in order to obtain the desired performance. Measured results of the fabricated antenna prototypes are in good agreement with simulated results. The measured dipole Yagi antenna yields 11 dB gain over 14% bandwidth with a size of 80 × 80 × 29 mm3. Radiation patterns of the dual-polarized Yagi antenna are nearly identical to those of the single-polarized antenna, which has a size of 50 × 50 × 60 mm3, and also its two-port isolation is found to be as low as 25 dB over 4% bandwidth. The proposed antennas present an excellent candidate for compact and low-cost microwave and millimeter-wave integrated systems that require fixed or variable polarization capabilities and small surface footprint. [ABSTRACT FROM AUTHOR]

In this paper, a 4 x 4 Nolen matrix beam-forming network for multibeam antenna applications is designed and demonstrated at 12.5-GHz center frequency. The structure is implemented using substrate integrated waveguide (SIW) technology for its attractive advantages including compact size, low loss, light weight, and planar form well suitable for high-density integration with other microwave and millimeter-wave planar integrated circuits. SIW cruciform couplers are used as fundamental building blocks for their wide range of coupling factors and their specific topology well adapted to the serial feeding topology of a Nolen matrix. The network performances are investigated over a 500-MHz frequency bandwidth ranging from 12.25 to 12.75 GHz. The matrix definition based on SIW cruciform couplers is similar to its microstrip counterpart in terms of coupling factors and phase delays. The whole network is fabricated. Measured results are in good agreement with the theoretical predictions, thus validating the proposed design concept. Using this matrix with a four radiating elements array antenna enables us to investigate the impact of the proposed matrix on the beam pointing angles versus frequency. [ABSTRACT FROM AUTHOR]

In this work, a single coupled cavity has presented for millimeter‐wave applications. The cavity is modeled to study the effect on the quality factor by adding cylindrical posts to coupled cavity resonator. This cavity model demonstrates a higher quality factor result and better performance compare to empty substrate integrated waveguide (ESIW) filter. The concept of enhancing the quality factor by adding posts is achieved. Based on this concept, the coupled cavity and bandpass filter are presented to show the feasibility of the fabrication process for building an ESIW filter where cylindrical posts is placed in middle on the planar substrate. The introduced cavity offers very good performance around (1%) fractal bandwidth at 24.7 GHz center frequency with Q‐factor of 2236. A cavity prototype is fabricated and measured where measurements agree well with simulation. [ABSTRACT FROM AUTHOR]

In this paper, mode composite waveguide (MCW) is proposed, which consists of inner and outer wave-guiding duo structures. The outer structure acts as a rectangular coaxial line suitable for lower frequency operation for its compact size, while the inner structure works as a rectangular waveguide suitable for higher frequency operation thanks to its simple structure and low loss. The MCW can propagate signals in the inner waveguide with TE10 mode and/or the outer waveguide with TEM mode depending on frequency to achieve optimal performance for both low- and high-frequency operations. In this paper, the fundamental waveguide parameters and higher order modes of the duo waveguides are examined. The proposed MCW prototypes are fabricated on a triple-layer PCB structure using the emerging substrate integration techniques. The MCW is fabricated and measured through the proposed microstrip line to the inner and outer waveguide transitions, and an MCW simultaneous feeding circuit is also presented. For this simultaneous feeding circuit, the good matching is achieved from 7.5 to 10.5 GHz for the low-frequency operation and from 25 to 39 GHz for the high-frequency operation, respectively. [ABSTRACT FROM PUBLISHER]

The detuning owing to the complex in-body operating scenarios, environmental factors, and circuitry of the implantable medical devices (IMDs) are the primary concerns in integrating implantable antennas with their corresponding systems. The wide bandwidth achievement for avoiding the detuning challenges is constrained by device specifications and antenna miniaturization. This study presents an ultra-miniaturized antenna of only 10.66 mm3 volume with an ultra-wide bandwidth of 3040 MHz (0.79–3.83 GHz) for a leadless pacemaker (LP). The proposed antenna encompasses the five important bands: ISM (868–868.6 MHz, 902–928 MHz, and 2.4–2.48 GHz), Wireless Medical Telemetry Service (WMTS) (1395–1400 MHz), and the midfield (1.45–1.6 GHz) bands. To consider a practical operating scenario, the antenna was integrated with a battery and controlling electronics of an LP. In a homogeneous heart phantom (HHP), the proposed antenna showed a higher gain of −28.7, −20.02, and −16.7 dBi at 915 MHz, 1.4 GHz, and 2.45 GHz, respectively. The specific absorption rate (SAR) evaluation in the heart of a realistic model guaranteed patient safety by satisfying the IEEE C95.1-2005 and C95.1-1999 guidelines. The antenna is experimentally validated through measurements in minced pork. The strength of the received signal in the measurements confirms a stable biotelemetric link of the proposed ultra-wideband (UWB) antenna with an external monitoring system. The results obtained through simulations and in vitro testing emphasized that the proposed ultra-miniaturized and UWB antenna could operate more efficiently in the heart, thus establishing itself as a suitable candidate for the LPs. [ABSTRACT FROM AUTHOR]

This article presents an efficient ultra-miniaturized metasurface-based antenna array with high gain and wider bandwidth for millimeter-wave applications. The presented 1 × 2 compact array incorporates two patches with rectangular slots for gain, impedance matching, and bandwidth enhancement. Further performance is improved by designing a single-layer compact reflecting metasurface with a 2 × 4 array of diamond-shaped split-ring unit cells, where each unit cell has a compact size of only 1.35 × 1.35 mm 2. A Fabry–Perot cavity is created by positioning this metasurface at approximately 0.5 λ 0 (where λ 0 is the wavelength in millimeters) above the antenna array. This integration allows for improved performance and reduced interference between the metasurface and the antenna array. Moreover, the proposed configuration has achieved a wider bandwidth of 5.96 GHz (27.38–33.34 GHz), a maximum gain of around 12.7 dBi, and a radiation efficiency of 94% despite its 20. 5 × 20. 6 × 0. 508 mm 3 miniaturized size. The design is validated by testing the fabricated prototypes. Compared to state-of-the-art literature, the proposed design renders itself a feasible solution for millimeter wave communication devices and systems owing to its smaller physical footprint, broader bandwidth, higher gain, and improved radiation efficiency. [ABSTRACT FROM AUTHOR]

This work aims to enhance the performance of a photo voltaic (PV) solar cell consisting of four layers: SiNx thin film sandwiched between glass and graded index metamaterials (GIM) topped by air. In particular, the work is aiming to widen the bandwidth at which the PV has near zero reflection and high transmission as close to 1. To satisfy the aim of the work, a 1-D photonic crystal (PC) with a specific structure is added to the top of the PV to minimize reflection. Then, the photonic crystal is used to surround the PV. In this case, PC consists of an alternating layer of polymer-dopped nanoparticles and air. In the calculations, the transfer matrix method (TMM) is used to calculate the transmittance as well as the reflectance for both systems at different layers' thicknesses. Then compared results for PV alone with PV topped with PC and PV surrounded by PC. It is found that using PC to encapsulate PV gives better results where PV will have almost zero reflection for a large range of spectrum compared to PC topping PV and PV without PC. The highest transmission and lowest reflections occur at n 2 = 2.2, d 1 = 40 nm and d 2 = 40 nm where transmission is higher than.8 and reflection are below 0.2. Thus, the proposed structure is capable of reducing power dissipation and enhancing the efficiency of the solar cell. It is recommended to add a PC to surround PV to get a wider range of spectrum at which transmittance is close to 1. [ABSTRACT FROM AUTHOR]

The use of error-correcting codes (ECCs) is essential for designing reliable digital communication systems. Usually, most systems correct errors under cooperative environments. If receivers do not know interleaver parameters, they must first find out them to decode. In this paper, a blind interleaver parameters estimation method is proposed using the Kolmogorov–Smirnov (K–S) test. We exploit the fact that rank distributions of square matrices of linear codes differ from those of random sequences owing to the linear dependence of linear codes. We use the K–S test to make decision whether two groups are extracted from the same distribution. The K–S test value is used as a measure to find the most different rank distribution for the blind interleaver parameters estimation. In addition to control false alarm rates, multinomial distribution is used to calculate the probability that the most different rank distribution will occur. By exploiting those, we can estimate the interleaver period with relatively low complexity. Experimental results show that the proposed algorithm outperforms previous methods regardless of the bit error rate. [ABSTRACT FROM AUTHOR]

The ever-growing expectation for high data rates has led to the introduction of multiple-input multiple-output (MIMO) technologies to wireless connectivity. Such a system requires an MIMO antenna with high isolation. At the same time, the MIMO dimension should not be compromised for achieving high isolation. Thus, isolation techniques that do not allow an increase in dimension need to be fostered for MIMO antenna design. In this paper, a novel low-profile, miniaturized MIMO antenna with high isolation was developed considering a split ring resonator (SRR)-based bandstop filter as a decoupling network. The bandstop filter was designed with a unit cell split ring resonator structure and was deployed between two closely spaced monopole MIMO antenna elements to obtain isolation as high as 39.25 dB at 2.61 GHz. Two open-circuit stub lines were attached with the MIMO feeding network to achieve good impedance matching at resonance frequency. The proposed antenna exhibited a peak gain of 3.8 dBi and radiation efficiency of 84%. It had a low envelop correlation coefficient (ECC < 0.12), high diversity gain (DG > 9.95 dB), low mean effective gain ratio (MEG 1/MEG 2 < 0.05 dB), and low channel capacity loss (CCL < 0.042 bits/s/Hz) at resonance frequency. The overall antenna dimension was restricted to 44   mm   × 22   mm   (0.38   λ 0 × 0.19   λ 0) for its easy integration in compact wireless devices. [ABSTRACT FROM AUTHOR]