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In mm-wave MIMO systems, hybrid precoder and combiner designs enhance antenna gain for improved transmission efficiency. However, beam-squint conditions during transmission impact throughput, affecting codebook and increasing beam focus and angle of arrival difference, degrading channel performance. Hence, a novel the Pylon ∂ PSO Method has been proposed to minimize codebook size and array gain, reducing the difference between beam focus and angle of arrival. A Grassmannian codebook is created without compromising throughput. For channel state estimation, existing techniques using the Kronecker product which face convergence errors due to improper hyperparameter matrix selection. Hence, an innovative Lagrange Dual technique and Separable K-Singular Value DE polymerization (K-SVDEp) have been used in dictionary learning that results in the Pt3 product to find the best dictionaries in which block sparse values are estimated using a Deep Ridge Regression Neural Network-based estimator that gives an optimum hyperparameter matrix and eliminates convergence error. Furthermore, designing a combiner from the hyperparameter matrix faces mathematical challenges. Hence, a novel Glasgow technique is utilized which converges the design parameter value with a local optimum obtained using the GEO algorithm. The proposed design has been implemented on the MATLAB platform and outperforms existing techniques with a high spectral efficiency of 45 bits/Hz, SNR of 13.4 dB, and low SER of 1 0 - 4 . [ABSTRACT FROM AUTHOR]

This article presents a meticulously engineered MIMO antenna system tailored specifically for 26 GHz millimeter-wave applications. It integrates a compact planar-patterned metamaterial (MTM) structure, carefully designed with split square and hexagonal unit cells to realize an effective near-zero index (NZI) range for both permeability and permittivity. Comprehensive wave propagation analysis along the y-axis rigorously examines the MTM's characteristics. The antenna system showcases impressive technical attributes, including an extensive 8.7 GHz bandwidth, notably highlighting mu-near-zero (MNZ) characteristics spanning over 8.7 GHz wide frequency spectrum, and epsilon near zero (ENZ) properties covering 8 GHz (26–34 GHz). Notably, a 4-ports MIMO antenna design is adopted with each element meticulously crafted using a 4-unit cell array configuration. The designed 4 × 4 MIMO antenna is fabricated using Rogers RT/duroid 5880 substrate and it occupies a compact dimension of 45.5 × 45.5 × 0.8 mm3. Experimental validation reveals compelling performance metrics, including a bandwidth spanning from 24.3 to 30.9 GHz, isolation levels below − 25 dB, and a maximum peak gain of 15.48 dBi. Additionally, the antenna exhibits circular polarization characteristics, maintaining an axial ratio below 3 dB within the frequency bands of 25.35 to 28.05 GHz and 28.10 to 29.83 GHz. Furthermore, the fabricated MIMO antenna demonstrates outstanding diversity parameters, exemplified by a high diversity gain (DG > 9.99), low envelope correlation coefficient (ECC < 0.0001), minimal channel capacity loss (CCL < 0.5), and total active reflection coefficient (TARC < − 8 dB). The suggested MTM-based MIMO antenna system with sophisticated design and exceptional performance could be an exemplary choice for seamless integration into the evolving landscape of 5G NR networks, particularly those operating within the n257/n258/n261 bands. [ABSTRACT FROM AUTHOR]

Signal loss remains a persistent challenge in communication systems, impacting Multiple Input Multiple Output (MIMO) systems, especially in the millimeter-wave (mm-Wave) context. This paper explores the effectiveness of the proposed Hybrid Precoding/Combining Design (HPCD) algorithm within a fully connected structure of an mm-Wave downlink massive MIMO system. The primary objective is to enhance the overall system's performance, specifically focusing on improving spectral efficiency. Simulation results consistently demonstrate the superiority of the HPCD algorithm over state-of-the-art techniques, revealing substantial improvements in spectral efficiency. This thorough examination highlights the potential of the proposed approach, positioning it as a compelling solution for next-generation communication networks. The findings are anticipated to significantly contribute to spectral efficiency optimization, facilitating the seamless integration of the proposed technique into practical communication scenarios. [ABSTRACT FROM AUTHOR]

This manuscript proposed a compact four-port multiple input multiple output (MIMO) antenna based on four split-ring resonators (SRR) at the top and a defected ground structure (DGS) at the bottom of the substrate for 5G communication. SRRs are used to resonate at 4 GHz frequency in mid-5G band. A slot of " + " symbol is cut at the bottom (DGS) to enlarge the bandwidth. The proposed antenna also achieved a high-5G frequency band (26.8–29.8 GHz) (n257/n258 band) by four square-shaped ring slots at the ground plane. It further enhances the bandwidth in mid-5G band (2.9–6 GHz) (n74/n75/n76/n77/n78 band) and helps to achieve a high degree of isolation between each radiating element (over 40 dB) at both the 5G bands. The size of the proposed MIMO antenna is 60 mm × 60 mm × 1.6 mm. It achieves a maximum gain of 4.59 dB, 4.32 dB at the mid-5G and high-5G band, respectively. The maximum radiation efficiencies achieved are 89%, 81% at the mid-5G and high-5G band, respectively. The diversity functionality of the antenna is also outstanding as the value of ECC is 0.01–0.42, DG is 9.6–10 dB, and TARC is less than − 10 dB measured in both the bands. The entire performance of the proposed antenna is practically verified, discussed and presented. [ABSTRACT FROM AUTHOR]

This study presents a symmetrical two-element Multiple-Input Multiple-Output (MIMO) antenna that exploits a feasible spectrum for 5G millimetre structure on the ground plane.It is attained to one additional operating mode at 24 GHz. A Rogers RT5880 substrate material is used in the construction of the proposed MIMO antenna. This substrate material has dimensions of 0.064 λ × 0.012 λ (at 24 GHz), a thickness of 0.8 mm, and a dielectric constant of 2.2.The results of the testing suggest that the antenna has the potential to span a frequency range that stretches from 23.5 to 25.5 GHz (6.1%) and from 34.2 to 36.4 (8.2%) GHz. In addition, the antenna does not need the usage of a sophisticated decoupling structure in order to achieve an inter-port isolation of higher than 15 dB between the antenna components across both bands. This is possible since the antenna is dual-banded. The results that were obtained from the measurement of the antenna after it was put through its paces are as follows. The components that make up this diagram are merged together to form a single entity. An envelope correlation coefficient of less than 0.005 and a channel capacity loss of less than 0.315 bits/s/Hz are the results of analysing the diversity performance characteristics. These results are totally compatible with the criteria and norms that are taken into consideration to be acceptable as a whole. The findings demonstrate that the design can successfully transmit millimetre waves at 5G rates, which was the goal of the study. [ABSTRACT FROM AUTHOR]

A wearable millimetre-wave radar antenna operating in 24.05–24.25 GHz for imaging applications in collision avoidance to assist visually impaired people is presented. Non-uniform excitation for the series end-fed 1 × 10 array antenna is optimized in simulation achieving a modified Dolph–Chebyshev distribution, which provides improved performance in terms of beam width, Side-lobe level and Gain. Commercial RO3003 and eco-friendly polypropylene (PP) are considered as substrates for comparison purposes, being the PP electromagnetically characterized for the first time at such high frequencies. Consistent agreement between simulation and measurement results is achieved for antenna prototypes on both dielectrics. The impedance matching bandwidth is analysed for the antenna on PP also under bent conditions. The overall size of the compact, low-cost, eco-friendly and flexible antenna on PP is 98.68 × 14.4 × 0.52 mm3 and, according to literature survey, it overcomes the state of the art on wearable radar antennas at 24 GHz. [ABSTRACT FROM AUTHOR]

In this work, a compact, edge-fed modified rectangular patch size, monopole, and ultra-wideband antenna has been presented for their good suitability to millimeter (mm) wave and upper sub-6 GHz frequency range (FR2) for next-generation (5G and beyond) communications. The patch size enhancement approach has been utilized without affecting the original size of the substrate and rectangular patch. The technique provides better impedance matching at the designed frequency of 32.5 GHz. The minimum acceptable gain for an antenna to work well is 5 dBi. The proposed design achieves peak gain of 5.43 dBi and 10.86 dBi at two resonance frequencies of 32.5 GHz and 48.12 GHz within the specified ultra-wideband (UWB). The antenna has low loss as it is fabricated on a compact Rogers RT Duroid 5880 of thickness 1.6 mm. The measured reflection coefficients are found in good agreement with the simulated one. The resultant performance parameters like radiation pattern, reflection coefficient, peak gain, and − 10 dB bandwidth reveal that the antenna performs excellently within 26 to 40 GHz with excellent impedance matching at the resonance frequency. At higher frequencies, the time domain response of the proposed design is also presented. The RLC electrical equivalent circuit of the proposed design is presented at the end and validated using ADS software. [ABSTRACT FROM AUTHOR]

A compact MIMO antenna with circular polarization, high gain, wide operating bandwidth, and a compact size is designed and suggested for mm-wave 5G applications. The propounded MIMO configuration contains four patch elements of similar geometries in 4 × 4 arrangement with individual E-shaped partial ground planes. The desired range of wide operating band with circular polarization, high gain, and high isolation has been achieved by modifying the structure of each single antenna element by integrating circular and semi-circular shaped slots in presence of rectangular slots loaded partial ground planes. The suggested MIMO antenna has been fabricated on a 1.67 mm thick Rogers RT/duroid 5870 substrate of 31.5 × 38.5 mm2. The fabricated and tested prototype of the suggested antenna verifies the simulation results. The suggested MIMO configuration offers a wide bandwidth of 8.1 GHz (34.4–42.5 GHz), high peak gain of about 18.5 dB and isolation of ≤−16 dB for the full working range. Besides, the presented antenna is circular polarized. This property allows the proposed antenna to emit the electromagnetic waves with a rotating electric field which allows the signal to propagate in different directions, providing better coverage and reducing the impact of signal polarization. The proposed antenna exhibits a standard MIMO performance by offering attractive diversity parameters. The proposed MIMO antenna is appropriate for 5G NR frequency band n260 (37–40 GHz) covering the allocated bandwidth requirements of different countries including UK (37–40), USA (37–37.6), Canada (37.6–40.0), and Australia (39 GHz). [ABSTRACT FROM AUTHOR]

Any wireless communication system's performance depends on channel parameters' accuracy. The classical Rayleigh and Nakagami-m research subjects remain vital even in the most modern millimeter-wave (mm-wave) applications. This research aims to create a generalized cumulative distribution function for describing random changes in wireless channels. It is vital to have a suitable channel representation model to represent varied fifth-generation applications to ease network implementation. This study provides mm-wave measurement data at 28 GHz carrier frequencies in line of sight and non-line of sight propagation. Lognormal, Nakagami, Gaussian, Weibull, and Rayleigh distributions outperform the proposed model's universal exponential density function. The experimental data verified the introduced method. [ABSTRACT FROM AUTHOR]

This work presents a symmetrical quad-element multiple-input multiple-output (MIMO) antenna that uses a feasible band for 5G millimeter waves at 38 GHz. The main radiator is a patch antenna with a rectangular shape, and the frequency it operates at is 38 GHz. Etching a three-element split-ring resonator (SRR) metamaterial unit cell onto the normal patch radiator allows for widening the resonance over the desired operating band. The suggested MIMO antenna is built on a Rogers RT5880 substrate material that measures 15 × 15 mm2, has a thickness of 0.8 mm, and has a dielectric constant of 2.2. The results of the measurements show that the antenna is capable of covering a frequency range from 37.3 to 39.3 GHz and can also achieve an inter-port isolation of greater than 20 dB between the antenna elements across both bands without the use of a complex decoupling structure. These are the results that were obtained when the antenna was tested. An equivalent circuit diagram of the electrical responses of the antenna is also presented to get insight into the proposed antenna. This schematic makes use of lumped components. The diversity performance parameters that were analyzed provide an envelope correlation coefficient that is less than 0.005, and a channel capacity loss that is less than 0.35 bits/s/Hz. All of these results fall well within the parameters that are considered acceptable norms. The findings provide evidence that the design is workable for the transmission of millimeter waves at 5G speeds. [ABSTRACT FROM AUTHOR]

A dual-band 28/38 GHz multiple-input multiple-output (MIMO) two elements antenna for the next 5G network is proposed in this paper. The single element is composed of a slot monopole antenna loaded with stub and a small crescent with an entire size of 15 × 15 mm2. The two elements are added to compose the suggested configuration. One of the antennas is printed on the upper layer while the other is located on it's back of the substrate to improve the coupling between elements without using any decoupling structures. The innovative antenna of dual-band works at 28/38 GHz and is achieved by adjusting the stub length and the crescent radius. The introduced MIMO antenna system has been experimented and the results have the same compatible trace with the simulated outcomes. The proposed two ports MIMO achieved a reasonable gain that reaches 5.7 and 6.9 dBi in the 28/38 GHz bands, respectively. The proposed MIMO antenna performance is also analyzed and achieved the envelope correlation coefficient, a diversity gain, and channel capacity Loss of about 10–4, 10 dB, and less than 0.3 bit/s/Hz, respectively over the 28/38 GHz bands. Finally, from the simulated and measured outcomes, it can be confirmed that the suggested MIMO antenna system can be applied to 5G wireless telecommunication applications. [ABSTRACT FROM AUTHOR]

Signal loss is a basic issue in any communication system. Multiple Input Multiple Output (MIMO) also faces a similar challenge. In Millimeter-Wave (mm-Wave) or massive MIMO systems, beamforming gain is a feature to manage such challenges. The advanced MIMO systems need an intelligent beamforming controller for better signal reception. Therefore, Hybrid Beamforming, a combination of both beamforming techniques, analog and digital, can overcome this problem. An mm-Wave downlink massive multi-user MIMO system has been considered based on a fully-connected structure for implementing the proposed algorithm. For this, focus on the overall system's performance which is maximized in terms of sum–rate and power efficiency. To improve the system's performance and reduce computational complexity, a successive approximation method is used to design the Digital Beamforming. Based on the criterion to minimize the path loss, the Analog Beamforming with the proposed dual iterative algorithm has been used to optimize the results which consist of outer and inner iterations for maximizing the sum–rate and improving power efficiency. The results showed that the proposed dual iterative algorithm achieves a better sum–rate and power efficiency than other state-of-the-art methods for both large and small base station antenna numbers. [ABSTRACT FROM AUTHOR]

The fifth-generation (5G) cellular networks will provide gigabit-per-second data rates from massive antenna array combined with the emerging use of large and unexploited millimeter wave (mm-Wave) bands (30–300 GHz) in small cells. Channel estimation for sparse mm-Wave MIMO systems is a difficult task. This is because of a large number of coefficients to be estimated, lower scattering nature, and blockage of mm-Wave by many materials in the environment. This paper will be the opportunity to implement the sparse channel estimation in the 5G cellular networks. In this work, we propose compressed-sensing (CS) based solutions and implements hybrid MIMO architecture for the proposed algorithm, OMP algorithm, and oracle estimator with different mm-Wave MIMO setups. Simulation results show that as compared to the OMP algorithm, proposed algorithm requires 16.9 times less computation time, and significant improvement is seen in normalized mean squared error (NMSE). Also, in the analysis, we found that the performance of the hybrid MIMO approaches near-optimal to conventional fully digital precoder. [ABSTRACT FROM AUTHOR]

The high gain, high speed/data rate, high capacity, and beamforming antennas are required for the present generation of mobile and wireless applications to satisfy the exponentially growing demands of the users. This paper presents low mutual coupling multiple input-multiple output (MIMO) array antenna for millimetre-wave (mmw) application. The MIMO-array beamforming antenna with 2:1 VSWR band is proposed for 28.0 GHz and covers 27.04–28.35 GHz frequency band, which is suitable for mm-wave n261 5G-band which cover the frequency range from 27.5–28.35 GHz. It consists of 2 × 12 antenna array elements and the prototype is designed on low loss Rogers Duroid 5880 substrate of size 51.45 × 36.87 mm 2. The beamforming MIMO antenna covers ± 20 0 main lobe directions. The mutual coupling at the MIMO-array ports is less than 28.0 dB. The radiation efficiency and the gain in the presented band are more than 93.0% and more than 13.99 dBi. The ECC in the presented frequency band is ≤ 10 - 4 , which is one of the advantages of the proposed design. The design covers indoor and outdoor Gaussian applications, and has 1.31 GHz TARC active bandwidth. It has 4.65% simulated and 4.73% measured fractional bandwidths. [ABSTRACT FROM AUTHOR]

Multi Input Multi Output (MIMO) and phased array systems are considered a key technologies to realize the 5G communication systems. Therefore, the purpose of this research is the suggestion of a novel mm-wave Ultrawide Band (UWB) antenna design with compact and straightforward layout suitable for both MIMO and phased array systems. Hence, the designed antenna array has been studied separately as a MIMO antenna and as a phased array antenna to carefully assess the performance of each system. The single antenna design is an elliptical patch antenna where the design novelty lies in the combination of a modified inset-feed and defected ground structure to provide a large bandwidth without any compromise in the radiation performance, nor in antenna size and design simplicity. The Design process are performed using CST MWS software, where the Rogers RT/Duroid 5880 substrate is chosen to construct the antenna. A broadband characteristic of 8.7 GHz from 26 to 34.7 GHz with two resonant frequencies at 28 GHz and 33 GHz is obtained. A good radiation properties are achieved, where the gain is greater than 4.5 dB while the radiation efficiency exceeds 97% over the operating band. The MIMO and phased array antennas are made up of 12-elements of the single UWB-antenna arranged linearly along the width-edge of the smartphone mainboard. The MIMO antenna proves a high diversity performance in terms of Diversity Gain (DG), Envelope Correlation Coefficient (ECC), Total Active Reflection Coefficient (TARC), Channel Capacity Loss (CCL) and Mean Effective Gain (MEG), owing to the low mutual coupling less than − 20 dB, which is obtained using a separating slits between the elements. In addition, the suggested phased array provides a highly stable gain up to 15 dB over the entire bandwidth at broadside direction, besides the wide scanning range of ± 60° at 28 GHz and ± 40° at 33 GHz. Hence, the attained results assure that the suggested antenna could be appropriate for incorporation in 5G smartphones and other wireless devices and can be effectively used for both phased array and MIMO applications. [ABSTRACT FROM AUTHOR]

In this paper, mm–wave low cost single and multiple input and multiple output (MIMO) planar microstrip antenna suitable for futuristic K–(18–26.5GHz), K a –band (26.5–40GHz) and local multipoint distribution systems (LMDS) applications is presented. The proposed structure achieves impedance bandwidth of 22.77 GHz (17.23–40GHz) with a peak gain of 13.69 dBi that notably covers the LMDS modern wireless communication application requirement. This achieves 5 dBi gain-bandwidth of 9.07 GHz (26.77–35.85GHz) and 17 GHz (19–36GHz) for single element and MIMO antenna with four elements in cascaded form respectively. The improvement in gain and impedance bandwidth is augmented after exciting multiple resonances of antenna by etching of two 3-armed H-shaped slots (3-AHSS) and inverted T-shaped slots (ITSS) symmetrically in the patch. With these etchings the copper losses and vertical components of current are controlled. The fabricated prototype of size 37 × 15 m m 2 is connected through a mm–wave supporting frequency connector of 2.92 mm and 50 Ω coaxial type to Vector Network Analyzer (VNA) Bench of modal number Rohde and Schwarz (ZNB–40) for measurement of performance parameters and it is found to be in good promise with simulated results. [ABSTRACT FROM AUTHOR]

The application of millimeter-wave (mm-wave) frequencies in communication has the potential to address the ever-growing data traffic requirements of next-generation wireless communication devices. However, owing to their high directivity and high penetration loss, directional mm-wave beams are vulnerable to blockages caused by users' bodies and ambient obstacles. Further development of indoor mm-wave communication is essential, as the majority of data traffic is generated in indoor environments. In previous studies, the mm-wave blockage problem was primarily considered in outdoor scenarios, whereas in the present study, online learning-based beam and blockage prediction in an indoor hotspot (InH) scenario was investigated. During an offline training phase, we constructed a fingerprinting database consisting of user locations along with their respective data traffic demands and corresponding blockage statuses with optimal beam indices. Following its creation, the fingerprinting database was used to train the weights and bias of a properly designed deep neural network (DNN). During a subsequent online learning phase, the trained DNN was fed user locations and corresponding data traffic demands at the served user equipment to output optimal beam indices and blockage statuses. System-level simulations were conducted to assess the accuracy of blockage prediction based on 3GPP's new radio channel and blockage models in InH environments. Simulation results revealed that the proposed scheme was capable of predicting mm-wave blockages with an accuracy of > 90%. These results confirmed the viability of the proposed DNN model for predicting optimal mm-wave beams and spectral efficiencies. [ABSTRACT FROM AUTHOR]

In this article, we propose a microstrip-fed printed meandered log-periodic monopole array (PMLPMA), and its dual-port configuration incorporating an octagonal ring frequency selective surface (FSS) layer. The dual-port PMLPMA antenna system has a compact structure with a total dimension of 18.75 × 18.75 mm2 and is designed to operate in the 5G n257 (28 GHz) band. The proposed PMLPMA radiator consists of five log-periodic monopole array elements, and the dual-port antenna system comprises two identical PMLPMAs placed vertically next to each other. Additionally, an octagonal ring-shaped single-layer FSS was implemented on the proposed antenna system to increase the gain across the operational band. Simulation results demonstrate that the dual-port PMLPMA antenna achieves a peak gain of about 3.5 dBi without the FSS layer, while a peak gain of 7.35 dBi is achieved when the FSS layer is augmented on the antenna. Moreover, isolation levels exceeding 30 dB are obtained for both cases between the 26.5–29.5 GHz frequency ranges. To verify the simulation results, the dual-port PMLPMA antenna system, and the octagonal ring-shaped FSS layer are also prototyped. The measurements align closely with the simulations in terms of performance criteria such as gain, bandwidth, and radiation patterns. Thus, the 28 GHz band antenna system exhibits great potential for 5G mobile applications. [ABSTRACT FROM AUTHOR]

All-metal 3D printing fabrication technologies provide an attractive alternative for direct manufacturing of waveguide components due to fast and cost-effective prototyping and the possibility to fabricate geometries which cannot be fabricated with traditional machining techniques. In radio astronomy, waveguide components in radio receivers are operated at cryogenic temperatures and inside a cryostat under vacuum conditions. In this paper, we report on the design, fabrication by 3D printing and testing at room and cryogenic temperatures of a corrugated horn to be used in astronomical receivers operating in the 35–50-GHz band. [ABSTRACT FROM AUTHOR]

Increased parasitic components in silicon-based nanometer (nm) scale active devices have various performance trade-offs between optimizing the key parameters, for example, maximum frequency of oscillation ( f max , gate resistance and capacitance, etc. A common-source cascode device is commonly used in amplifier designs at RF/millimeter-wave (mmWave) frequencies. In addition to intrinsic parasitic components, extrinsic components due to wiring and layout effects, are also critical for performance and accurate modelling of the devices. In this work, a comparison of two different layout techniques for cascode devices is presented to optimize the extrinsic parasitic elements, such as gate resistance. A multi-gate or multi-port layout technique is proposed for optimizing the gate resistance ( r g ). Extracted values from measurement results show reduction of 10% in r g of multi-gate layout technique compared to a conventional gate-above-device layout for cascode devices. However, conventional layout exhibits smaller gate-to-source and gate-to-drain capacitances which leads to better performance in terms of speed, i.e. f max . An LNA is designed at 40 GHz frequency using proposed multi-gate cascode device. LNA achieves a measured peak gain of 10.2 dB and noise figure of 4.2 dB at 40 GHz. All the structures are designed and fabricated using 45 nm CMOS silicon on insulator (SOI) technology. [ABSTRACT FROM AUTHOR]

A position-aided fast beam training in mm-Wave multiuser MIMO systems (PAFBT) method is proposed, in the case of inexact position information. Position information can be used to compute the pointing direction and essentially eliminate the beam alignment overhead. But the incorrect position information will introduce the beam misalignment. To solve the estimated received nodes location uncertainty problem, a beam training scheme is conducted by transmitting the beams to cover critical areas of the received nodes to find out the best transmitter and receiver beams for establishing the links in mm-Wave multiuser MIMO systems. Mathematical and simulation analysis confirm the superiority of the proposed method over the conventional ones in performance. [ABSTRACT FROM AUTHOR]

For the first time, a mm-wave personal exposure meter (mm-PEM) for the 5th generation of mobile networks (5G) exposure assessment in indoor diffuse fields is presented. The design is based on simulations and on-phantom calibration measurements in a mm-wave reverberation chamber (RC) at 60 GHz. The mm-PEM consists of an array of nine antennas on the body. Using the mm-PEM, the incident power density (IPD) is measured in the unloaded RC, for the antenna(s) on the phantom and RC loaded with phantom. The uncertainty of the mm-PEM is then determined in terms of its response, which is defined as the ratio of antenna aperture for the above measurement scenarios. Using nine antennas, the designed meter has a response of 1.043 (0.17 dB) at 60 GHz, which is very close to 1 (0 dB), the desired ideal response value. The mm-PEM measured an IPD of 96.6 Wm− 2 at 60 GHz in the RC, for an input power of 1 W. In addition, the average absorption cross-section of the phantom is determined as 225 cm2, which is an excellent agreement with its physical dimensions. [ABSTRACT FROM AUTHOR]

We present a 60 GHz phased array system that combines several key technologies to realize 10 GHz bandwidth coverage. Particularly, a tightly coupled dipole array centered at 60 GHz is designed and tested for its wideband performance. The tightly coupled dipole elements offer excellent wideband behavior of 10 GHz with voltage standing wave ratio < 3 with scanning to 45°, as well as low cost printed circuit board fabrication. Additionally, we demonstrate a measurement setup with de-embedding procedure to measure gain at the antenna feed point. A feeding structure was designed and fabricated for de-embedding gain pattern measurements. Recovered measurements are shown to be in agreement with simulation. [ABSTRACT FROM AUTHOR]

We review advances in low-temperature detector (LTD) arrays for cosmic microwave background (CMB) polarization experiments, with a particular emphasis on imaging arrays. We briefly motivate the science case, which has spurred a large number of independent experimental efforts. We describe the challenges associated with CMB polarization measurements, and how these challenges impact LTD design. Key aspects of an ideal CMB polarization imaging array are developed and compared to the current state of the art. These aspects include dual-polarization sensitivity, background-limited detection over a 10:1 bandwidth ratio, and frequency-independent angular responses. Although existing technology lacks all of this capability, today’s CMB imaging arrays achieve many of these ideals and are highly advanced superconducting integrated circuits. Deployed arrays map the sky with pixels that contain elements for beam formation, polarization diplexing, passband definition in multiple frequency channels, and bolometric sensing. Several detector architectures are presented. We comment on the implementation of both transition-edge sensor bolometers and microwave kinetic inductance detectors for CMB applications. Lastly, we discuss fabrication capability in the context of next-generation instruments that call for ∼106 sensors. [ABSTRACT FROM AUTHOR]

SuperSpec is a new technology for mm and sub-mm spectroscopy. It is an on-chip spectrometer being developed for multi-object, moderate-resolution (R∼300), large bandwidth survey spectroscopy of high-redshift galaxies for the 1 mm atmospheric window. This band accesses the CO ladder in the redshift range of z= 0-4 and the [CII] 158 μm line from redshift z=  5-9. SuperSpec employs a novel architecture in which detectors are coupled to a series of resonant filters along a single microwave feedline instead of using dispersive optics. This construction allows for the creation of a full spectrometer occupying only ∼10cm2 of silicon, a reduction in size of several orders of magnitude when compared to standard grating spectrometers. This small profile enables the production of future multi-beam spectroscopic instruments envisioned for the millimeter band to measure the redshifts of dusty galaxies efficiently. The SuperSpec collaboration is currently pushing toward the deployment of a SuperSpec demonstration instrument in fall of 2018. The progress with the latest SuperSpec prototype devices is presented; reporting increased responsivity via a reduced inductor volume (2.6 μm3) and the incorporation of a new broadband antenna. A detector NEP of 3-4 ×10-18 W/Hz0.5 is obtained, sufficient for background-limited observation on mountaintop sites. In addition, beam maps and efficiency measurements of a new wide-band dual bow-tie slot antenna are shown. [ABSTRACT FROM AUTHOR]

The paper presents the first in vivo glucose monitoring animal study in a pig, which correlates radio frequency signal transmission changes with changes in blood glucose concentration in the 58-62 GHz frequency range. The presented non-invasive glucose sensing system consists of two opposite facing patch antennas sandwiching glucose-loaded samples. Prior to the animal study, the system was tested using saline solution samples, for which a linear relationship between changes in transmitted signal and glucose concentration was observed. In the animal study, glucose concentration changes were induced by injecting a known glucose solution in the blood stream. The non-invasive transmission measurements were compared to the glucose levels obtained invasively from the animal. Our results suggest that the system can detect spikes in glucose concentration in the blood, which is an important milestone towards non-invasive glucose monitoring. [ABSTRACT FROM AUTHOR]

This paper presents an energy-efficient digital front-end processor for digital-intensive polar transmitter architecture working on 60 GHz band in standard 28nm CMOS process. This avoids modulating the supply and also eliminates the need of an additional RF limiter and AM detection circuits in the traditional analog-centric polar transmitter architecture. The design challenges on the digital signal processing (DSP) front-end are analyzed and tackled. The systematic optimizations are first explored to minimize the design requirements on the DSP front-end. A pulse shaping filter is designed to shape the frequency spectrum of the quadrature signals so that the signal at the output of the filter is compliant with the spectrum mask requirements. Instead of using computation-intensive raised cosine filter for the pulse shaping, we use poly-phase Cascaded Integrator-Comb (CIC) filter to shape the spectrum. Parallel rotation and vectoring COordinate Rotation DIgital Computers (CORDICs) are designed to perform rectangular-to-polar conversion. Furthermore, a pre-distortion circuit based on look-up table (LUT) is designed to compensate the power amplifier (PA) nonlinearities. Taylor’s approximation is explored to avoid the complex trigonometric computation in the pre-distortion. Finally, an efficient latch-based pipeline is studied to provide the required 7.04 Gsps throughput with less than 60 mW. The synthesis results compare favorably with previously reported architectures. [ABSTRACT FROM AUTHOR]

Insightful choice of enabling technologies tend to effectuate a smooth transition from legacy networks to fifth generation wireless communication systems (5G). Future wireless networks must address exponential growth in connectivity, capacity and services, while perpetuating energy and cost reductions. It is therefore, crucial to intelligently evaluate key contenders of 5G evolution. This article provides an overview of ten fundamental concepts that could impact 5G framework. An outline of expected benefits is deliberated in this paper. We discuss compelling need of a new spectrum followed by associated changes in terms of air interface, architecture and MAC layer protocols. For alleviating access complexity in diverse-dense 5G deployment, we make a review on Heterogeneous-Cloud Radio Access Networks and Software Defined Networking. We also discuss two disruptive approaches with high research challenges, non orthogonality and full duplex. [ABSTRACT FROM AUTHOR]

The Atacama Large Millimeter/Sub-millimeter Array (ALMA) is currently the largest (sub-)mm wave telescope in the world and will be used for astronomical observations in all atmospheric windows from 35 to 950 GHz when completed. The ALMA band 1 (35-50 GHz) receiver will be used for the longest wavelength observations with ALMA. Because of the longer wavelength, the size of optics and waveguide components will be larger than for other ALMA bands. In addition, all components will be placed inside the ALMA cryostat in each antenna, which will impose severe mechanical constraints on the size and position of receiver optics components. Due to these constraints, the designs of the corrugated feed horn and lens optics are highly optimized to comply with the stringent ALMA optical requirements. In this paper, we perform several tolerance analyses to check the impact of fabrication errors in such an optimized design. Secondly, we analyze the effects of operating this optics inside the ALMA cryostat, in particular the effects of having the cryostat IR filters placed next to the band 1 feed horn aperture, with the consequent near-field effects. Finally, we report on beam measurements performed on the first three ALMA band 1 receivers inside test cryostats, which satisfy ALMA specifications. In these measurements, we can clearly observe the effects of fabrication tolerances and IR filter effects on prototype receiver performance. [ABSTRACT FROM AUTHOR]

Frequency bands above 6 GHz are being considered for future 5G wireless systems because of the larger bandwidth availability and of the smaller wavelength, which can ease the implementation of high-throughput massive MIMO schemes. However, great challenges are around the corner at each implementation level, including the achievement of a thorough multi-dimensional characterization of the mm-wave radio channel, which represents the base for the realization of reliable and high-performance radio interfaces and system architectures. The main properties of the indoor radio channel at 70 GHz, including angular and temporal dispersion as well as an assessment of the major interaction mechanisms, are investigated in this study by means of UWB directional measurements and ray tracing simulations in a reference, small-indoor office environment. [ABSTRACT FROM AUTHOR]

This paper presents simulation results for a sliding-IF SiGe E-band transmitter circuit for the 81-86 GHz E-band. The circuit was designed in a SiGe process with f = 200 GHz and uses a supply of 1.5 V. The low supply voltage eliminates the need for a dedicated transmitter voltage regulator. The carrier generation is based on a 28 GHz quadrature voltage oscillator (QVCO). Upconversion to 84 GHz is performed by first mixing with the QVCO signals, converting the signal from baseband to 28 GHz, and then mixing it with the 56 GHz QVCO second harmonic, present at the emitter nodes of the QVCO core devices. The second mixer is connected to a three-stage power amplifier utilizing capacitive cross-coupling to increase the gain, providing a saturated output power of +14 dBm with a 1 dB output compression point of +11 dBm. E-band radio links using higher order modulation, e.g. 64 QAM, are sensitive to I/Q phase errors. The presented design is based on a 28 GHz QVCO, the lower frequency reducing the phase error due to mismatch in active and passive devices. The I/Q mismatch can be further reduced by adjusting varactors connected to each QVCO output. The analog performance of the transmitter is based on ADS Momentum models of all inductors and transformers, and layout parasitic extracted views of the active parts. For the simulations with a 16 QAM modulated baseband input signal, however, the Momentum models were replaced with lumped equivalent models to ease simulator convergence. Constellation diagrams and error vector magnitude (EVM) were calculated in MATLAB using data from transient simulations. The EVM dependency on QVCO phase noise, I/Q imbalance and PA compression has been analyzed. For an average output power of 7.5 dBm, the design achieves 7.2% EVM for a 16 QAM signal with 1 GHz bandwidth. The current consumption of the transmitter, including the PA, equals 131 mA from a 1.5 V supply. [ABSTRACT FROM AUTHOR]

A 57-66 GHz 5-bit digitally controlled high-pass/direct-pass T-type phase shifter (PS) is presented in this paper in a 65 nm LP CMOS technology. Influence of body connection manners on insertion loss (IL) of nMOS switches in high-pass/direct-pass T-type PS is carefully investigated. Using body-floating technique, both low IL and excellent IL flatness are achieved simultaneously. The minimum and maximum IL are 8.8 and 17 dB, respectively, with a maximum IL flatness of ±1 dB and a maximum root mean square (rms) gain error of 1.6 dB across 57-66 GHz. The proposed PS also achieves a maximum rms phase error of 3.9°, a minimum input 1 dB power compression point (IP) of 13 dBm, while shows well matching characteristics, with both S11 and S22 of less than −8.5 dB across 57-66 GHz for every phase shifting state. [ABSTRACT FROM AUTHOR]

This paper presents two circuits, a complete 1.5 V 28 GHz SiGe beam steering PLL and a standalone 28 GHz QVCO with I/Q phase imbalance detection and compensation. The circuits were designed in a SiGe process with f = 200 GHz. The PLL is intended to be used for beam steering in an 81-86 GHz E-band transmitter. Phase control is implemented by DC current injection at the output of a Gilbert architecture phase detector showing a simulated phase control sensitivity of 1.2°/µA over a range close to 180°. The simulations use layout parasitics for the QVCO, frequency divider, and phase detector, and an electromagnetic model for the QVCO inductors. The divider is implemented with four cascaded divide-by-two current-mode-logic blocks for a reference frequency of 1.75 GHz. For closed loop simulations of PLL noise and stability, the QVCO is represented with a behavior model with added phase noise. This simulation technique enabled faster simulation time of the PLL. The PLL in band phase noise at 1 MHz offset equals −115 dBc/Hz. Excluding output buffers, the entire PLL consumes 52 mW plus a minimum 7 mW from a variable high voltage supply required to extend the PLL locking range. The measured phase noise of the standalone QVCO equals −100 dBc/Hz at 1 MHz offset. Since E-band radio links utilize higher order QAM modulation, the bit-error rate is sensitive to I/Q phase error. In the measured standalone QVCO with I/Q phase imbalance detection and compensation, the error is detected in two cross coupled active mixers that have an output DC level proportional to the phase error. The error can then be eliminated adjusting the bias of four varactors connected to the QVCO outputs. The current consumption of the chip equals 14 mA from a 1.5 V supply and 57 mA from a 2.5 V supply dedicated to the detector and 28 GHz output measurement buffers. [ABSTRACT FROM AUTHOR]

A low-noise (LNA) amplifier that combines transformer-neutralization with bandwidth enhancement is introduced to enable a compact design capable of operating from a widely scalable supply voltage. A supply-voltage scalable 17-29 GHz ultra-wideband (UWB) multi-stage LNA prototype employing a single transistor between V and ground in all stages, and using the aforementioned techniques, is fabricated in 130 nm CMOS. The LNA achieves 15.4 dB (18 dB) peak gain, 5.5 dB (4.7 dB) minimum NF and −12 dBm (−11 dBm) worst case IIP3 while consuming 6 mW (15 mW) power while operating with a 0.6 V (1.2 V) supply voltage. A 17-27 GHz quadrature receiver prototype employing a modified version of this LNA is also fabricated, with potential applications in wireless sensor and vehicular radar applications. The receiver achieves 22.2 dB (25.4 dB) of peak conversion gain, 8.7 dB (5.7 dB) minimum NF and −17 dBm (−15 dBm) worst case IIP3 while consuming 10.2 mW (24 mW) power from a 0.6 V (1.2 V) V. [ABSTRACT FROM AUTHOR]

Frequency pulling of an oscillator integrated in a quadrature phase-shift keying wireless transmitter degrades the performance of the wireless system. This paper analyses the behavior of an oscillator in the presence of coupling between the oscillator and a power amplifier or antenna. Symbol switching in the modulator will cause frequency shifts in the oscillator at the modulation frequency. A new architecture for a 120 GHz quadrature frequency generator with large tuning range and immunity against PA-VCO coupling is presented. Combining the output signals of two independent oscillators, the pulling effect is removed and the frequency generator can be integrated with a PA and an antenna on the same chip. This architecture also makes quadrature generation with large tuning range feasible at 120 GHz. The chip is fabricated in a 45 nm CMOS technology and shows a tuning range of 16.2 GHz (13.5 $$\%$$ ), a phase noise of $$-$$ 112 dBc/Hz @ 10 MHz offset and a phase error of 5 $$^\circ$$ (Volkaerts et al. in: IEEE Radio Frequency Integrated Circuits Symposium (RFIC), ). [ABSTRACT FROM AUTHOR]

The design and layout of a two stage SiGe E-band power amplifier using a stacked transformer for output power combination is presented. In EM-simulations with ADS Momentum, at E-band frequencies, the power combiner consisting of two individual single turn transformers performs significantly better than a single 2:1 transformer with two turns on the secondary side. Imbalances in the stacked transformer structure are reduced with tuning capacitors for maximum gain and output power. At 84 GHz the simulated loss of the stacked transformer is as low as 1.35 dB, superseding the performance of an also presented alternative power combiner. The power combination allows for a low supply voltage of 1 V, which is beneficial since the supply can then be shared between the power amplifier and the transceiver, thereby eliminating the need of a separate voltage regulator. To improve the gain of the two-stage amplifier it employs a capacitive cross-coupling technique not yet seen in mm-wave SiGe PAs. Capacitive cross-coupling is an effective technique for gain enhancement but is also sensitive to process variations as shown by Monte Carlo simulations. To mitigate this two alternative designs are presented with the cross coupling capacitors implemented either with diode coupled transistors or with varactors. The PA is designed in a SiGe process with f = 200 GHz and achieves a power gain of 12 dB, a saturated output power of 16 dBm and a 14 % peak PAE. Excluding decoupling capacitors it occupies a die area of 0.034 mm. [ABSTRACT FROM AUTHOR]

In this paper differential mode and common mode stability analysis of differential transformer-coupled CMOS mm-wave amplifiers with capacitive neutralization is investigated. Simulation of a differential amplifier implemented with a complete PSP transistor model shows that capacitive neutralization can improve the differential stability. In common mode however, the differential pair becomes potentially unstable over a wider frequency range. A robust common mode resistive stabilization technique, which ensures complete stability of the amplifier, is also discussed and analyzed. The analysis and stabilization techniques were successfully applied to stabilize a common mode unstable integrated F-band 45 nm CMOS amplifier. Measurements confirm the stabilization of the amplifier and a differential gain of 16 dB at 110 GHz is achieved. [ABSTRACT FROM AUTHOR]

A new time-domain two-dimensional (2D) electromagnetic (EM) physical modelling of non-linear distributed semiconductor devices has been developed. It is based on a numerical procedure which solves in a self consistent manner both Maxwell’s equations and a macroscopic transport model based on the drift-diffusion approximation. The software can be run on a parallel computer. It is based on finite-difference time-domain (FDTD) explicit schemes associated to the domain decomposition method. The millimetre-wave travelling-wave IMPATT diode or Distributed IMPact ionisation and Avalanche and Transit Time (DIMPATT) diode is the non linear test structure chosen to validate the model. RF simulations under amplification and CW oscillation operating modes have been performed. The results presented in this paper consist on the one hand of results that can be qualitatively compared to previously published theoretical works and on the other hand of features especially pointed out thanks to the new electromagnetic physical model capabilities. [ABSTRACT FROM AUTHOR]

The availability of millimeter wave (mm-Wave) band in conjunction with massive multiple-input-multiple-output (MIMO) technology is expected to boost the data rates of the fifth-generation (5G) cellular systems. However, in order to achieve high spectral efficiencies, an accurate channel estimate is required, which is a challenging task in massive MIMO. By exploiting the small number of paths that characterize the mm-Wave channel, the estimation problem can be solved by compressed-sensing (CS) techniques. In this paper, we propose a novel CS channel estimation method based on the accelerated gradient descent with adaptive restart (AGDAR) algorithm exploiting a ℓ1-norm approximation of the sparsity constraint. Moreover, a modified re-weighted compressed-sensing (RCS) technique is considered that iterates AGDAR using a weighted version of the ℓ1-norm term, where weights are adapted at each iteration. We also discuss the impact of cell sectorization and tracking on the channel estimation algorithm. We compare the proposed solutions with existing channel estimations with an extensive simulation campaign on downlink third-generation partnership project (3GPP) channel models. [ABSTRACT FROM AUTHOR]