Digital transformation in buildings accumulates massive operational data, which calls for smart solutions to utilize these data to improve energy performance. This study has proposed a solution, namely Deep Energy Twin, for integrating deep learning and digital twins to better understand building energy use and identify the potential for improving energy efficiency. Ontology was adopted to create parametric digital twins to provide consistency of data format across different systems in a building. Based on created digital twins and collected data, deep learning methods were used for performing data analytics to identify patterns and provide insights for energy optimization. As a demonstration, a case study was conducted in a public historic building in Norrköping, Sweden, to compare the performance of state-of-the-art deep learning architectures in building energy forecasting.

Historic buildings require good maintenance to sustain their function and preserve embodied heritage values. Previous studies have demonstrated the benefits of digitalization techniques in improving maintenance and managing threats to historic buildings. However, there still lacks a solution that can consistently organize data collected from historic buildings to reveal operating conditions of historic buildings in real-time and to facilitate various data analytics and simulations. This study aims to provide such a solution to help achieve preventive conservation. The proposed solution integrates Internet of Things and ontology to create digital twins of historic buildings. Internet of Things enables revealing the latest status of historic buildings, while ontology provides a consistent data schema for representing historic buildings. This study also gives a reference implementation by using public cloud services and open-source software libraries, which make it easier to be reused in other historic buildings. To verify the feasibility of the solution, we conducted a case study in the City Theatre, Norrköping, Sweden. The obtained results demonstrate the advantages of digital twins in providing maintenance knowledge and identifying potential risks caused by fluctuations of relative humidity.

Information and communication technologies (ICTs) help preserve historic buildings and optimize energy efficiency. This study proposes a digitalization framework for historic buildings by utilizing ICTs, such as Internet of Things (IoT), digital twins, and cloud computing. A digital twin is a digital representation of physical world assets that genuinely reflects the properties of real-world objects and processes. In this study, historic buildings are modeled with cloud-based digital twins. Indoor environmental data are collected with locally deployed sensors and ingested to a digital twin in real-time. The digital twin enables decision-makers to remotely monitor the indoor environment of a historic building and actively manipulate actuators to perform maintenance. Empowered by data analytics and artificial intelligence (AI), a digital twin can further simulate and predict state changes in a historic building to reach desired autonomous maintenance and energy saving.

Plant Factory is a newly emerging industry aiming at transforming crop production to an unprecedented model by leveraging industrial automation and informatics. However, todays plant factory and vertical farming industry are still in a primitive phase, and existing industrial cyber-physical systems are not optimal for a plant factory due to diverse application requirements on communication, computing and artificial intelligence. In this paper, we review use cases and requirements for future plant factories, and then dedicate an architecture that incorporates the communication and computing domains to plant factories with a preliminary proof-of-concept, which has been validated by both academic and industrial practices. We also call for a holistic co-design methodology that crosses the boundaries of communication, computing and artificial intelligence disciplines to guarantee the completeness of solution design and to speed up engineering implementation of plant factories and other industries sharing the same demands.

Monitoring the indoor environment of historic buildings helps to identify potential risks, provide guidelines for improving regular maintenance, and preserve cultural artifacts. However, most of the existing monitoring systems proposed for historic buildings are not for general digitization purposes that provide data for smart services employing, e.g., artificial intelligence with machine learning. In addition, considering that preserving historic buildings is a long-term process that demands preventive maintenance, a monitoring system requires stable and scalable storage and computing resources. In this paper, a digitalization framework is proposed for smart preservation of historic buildings. A sensing system following the architecture of this framework is implemented by integrating various advanced digitalization techniques, such as Internet of Things, Edge computing, and Cloud computing. The sensing system realizes remote data collection, enables viewing real-time and historical data, and provides the capability for performing real-time analysis to achieve preventive maintenance of historic buildings in future research. Field testing results show that the implemented sensing system has a 2% end-to-end loss rate for collecting data samples and the loss rate can be decreased to 0.3%. The low loss rate indicates that the proposed sensing system has high stability and meets the requirements for long-term monitoring of historic buildings.

This study proposes a digitalization framework for historic buildings. In this framework, advanced techniques, like Internet of Things (IoT), cloud computing, and artificial intelligence (AI), are utilized to create digital twins for historic buildings. A digital twin is a software representation of a physical object. This study uses digital twins to protect, predict, and optimize through analytics of real-time and historical data of selected features. Heterogeneous data of historic buildings, such as indoor environment, energy consumption metering, and outdoor climate, are collected with proper sensors or retrieved from other data sources. Then, these data are periodically uploaded and stored in the database of the cloud platform. Based on these data, AI models are trained through appropriate machine learning algorithms to monitor historic buildings, predict energy consumption, and control energy-consuming equipment autonomously to reach the balance of energy efficiency, building conservation, and human comfort. The cloud-based characteristic of our digitalization framework makes the digital twins developed in this study easy to be transplanted to many other historic buildings in Sweden and other countries.

Researches on the Internet of Things (IoT) and cloud computing have been pervasive in both the academic and industrial world. IoT and cloud computing are seen as cornerstones to digital transformation in the industry. However, restricted by limited resources and the lack of expertise in information and communication technologies, small- and medium-sized enterprises (SMEs) have difficulty in achieving digitalization of their business. In this paper, we propose a reference framework for SMEs to follow as a guideline in the journey of digital transformation. The framework features a three-stage procedure that covers business, technology, and innovation, which can be iterated to drive product and business development. A case study about digital transformation taking place in the vertical plant wall industry is detailed. Furthermore, some solution design principles that are concluded from real industrial practice are presented. This paper reviews the digital transformation practice in the vertical plant wall industry and aims to accelerate the pace of SMEs in the journey of digital transformation.

Today, the edge-cloud computing paradigm starts to gain increasing popularity, aiming to enable short latency, fast decision-making and intelligence at the network edge, especially for industrial applications. The container-based virtualization technology has been put on the roadmap by the industry to implement edge-cloud computing infrastructures. Has the performance of the container-based edge-cloud computing stacks reached industry requirement? In this paper, from the industrial client perspective, we provide a performance evaluation methodology and apply it to the state-of-the-art containerization-based edge-cloud computing infrastructures. The influences of the message sending interval, payload, network bandwidth and concurrent devices on full stack latency are measured, and the processing capability of executing machine learning tasks are benchmarked. The results show that containerization on the edge does not introduce noticeable performance degradation in terms of communication, computing and intelligence capabilities, making it a promising technology for the edge-cloud computing paradigm. However, there is a large room for performance improvement between current implementation of the edge-cloud infrastructure and the demanding requirements anticipated by time-critical industrial applications. We also emphasize and showcase that partitioning of an industrial application into microservices throughout the whole stack can be considered during solution design. The proposed evaluation methodology can be a reference to users of edge-cloud computing as well as developers to get a client perspective overview of system performance.

Indoor climate is closely related to human health, comfort and productivity. Vertical plant wall systems, embedded with sensors and actuators, have become a promising application for indoor climate control. In this study, we explore the possibility of applying machine learning based anomaly detection methods to vertical plant wall systems so as to enhance the automation and improve the intelligence to realize predictive maintenance of the indoor climate. Two categories of anomalies, namely point anomalies and contextual anomalies are researched. Prediction-based and pattern recognition-based methods are investigated and applied to indoor climate anomaly detection. The results show that neural network-based models, specifically the autoencoder (AE) and the long short-term memory encoder decoder (LSTM-ED) model surpass the others in terms of detecting point anomalies and contextual anomalies, respectively, therefore can be deployed into vertical plant walls systems in industrial practice. Based on the results, a new data cleaning method is proposed and a prediction-based method is deployed to the cloud in practice as a proof-of-concept. This study showcases the advancements in machine learning and Internet of things can be fully utilized by researches on building environment to accelerate the solution development.

Internet of Things (IoT) has been found pervasive use cases and become a driving force to constitute a digital society. The ultimate goal of IoT is data and the intelligence generated from data. With the progress in public cloud computing technologies, more and more data can be stored, processed and analyzed in cloud to release the power of IoT. However, due to the heterogeneity of hardware and communication protocols in the IoT world, the interoperability and compatibility among different link layer protocols, sub-systems, and back-end services have become a significant challenge to IoT practices. This challenge cannot be addressed by public cloud suppliers since their efforts are mainly put into software and platform services but can hardly be extended to end devices. In this paper, we propose a data-centric IoT framework that incorporates three promising protocols with fundamental security schemes, i.e., WiFi, Thread, and LoRaWAN, to cater to massive IoT and broadband IoT use cases in local, personal, and wide area networks. By taking advantages of the Azure cloud infrastructure, the framework features a unified device management model and data model to conquer the interoperability challenge. We also provide implementation and a case study to validate the framework for practical applications.

This paper describes a passive analog phase interpolator, utilizing a switched RC-network. The proposed circuit eliminates the current sources in a phase interpolator based on constant-slope charging. By eliminating the current source, the noise is significantly reduced due to the reduction in thermal and flicker noise. The phase interpolator has a resolution of 6 bits and is implemented in a 16-nm CMOS process. The maximum differential non-linearity is measured to be 0.1 LSBs at a 192 ps input time delta. The circuit draws 0.2 mW from a 0.8 V supply, and occupies 0.004 mm2.

A novel composite right/left-handed (CRLH) transmission line (TL) structure is proposed and investigated. This structure consists of a pair of broadside-coupled lines and a shorted stub. First, its fundamental characteristics and the relation between its electrical parameters and bandwidth are studied utilizing the TL theory. Then, closed-form design equations with flexible parameter selection are given. Finally, several microstrip implementations of the proposed structure are developed to verify our theoretical results. It is shown that the proposed structure can achieve a very wide left-handed (LH) and right-handed (RH) bandwidth with low insertion loss and low return loss.

The entire microwave theory is based on Maxwells equations, whereas the entire electronic circuit theory is based on Kirchhoffs electrical current and voltage laws. In this paper, we show that the traditional microwave design methodology can be simplified based on a broadside-coupled microstrip line as a low loss metamaterial. That is, Kirchhoffs laws are still valid in the microwave spectrum for narrowband signals around various designated frequencies. The invented low loss metamaterial has been theoretically analyzed, simulated, and experimentally verified in both time and frequency domains. It is shown that the phase velocity of a sinusoidal wave propagating on the low loss metamaterial can approach infinity, resulting in time-space shrink to a singularity as seen from the propagating wave perspective.

An indoor climate is closely related to human health, well-being and comfort. Thus, indoor climate monitoring and management are prevalent in many places, from public offices to residential houses. Our previous research has shown that an active plant wall system can effectively reduce the concentrations of particulate matter and volatile organic compounds and stabilize the carbon dioxide concentration in an indoor environment. However, regular plant care is restricted by geography and can be costly in terms of time and money, which poses a significant challenge to the widespread deployment of plant walls. In this article, we propose a remote monitoring and control system that is specific to the plant walls. The system utilizes the Internet of Things technology and the Azure public cloud platform to automate the management procedure, improve the scalability, enhance user experiences of plant walls, and contribute to a green indoor climate.

The need for energy efficiency in wireless communication is prevalent in all areas, but to an even greater extent in low-power and lossy networks (LLN) that rely on resource constrained devices. This article seeks to address the problem of modeling the battery lifetime of a duty-cycled node, participating in a wireless sensor network that is typically used in smart home and building applications. Modeling in MATLAB and experimentation with prototype testing are employed to predict and validate. Various scenarios including sleepy end devices in a wireless sensor network are modeled and validated. They range from variable wake-up frequency and packet payload transmission to increasing network contention with the addition of network load. A comprehensive analysis of the main factors contributing to wasteful energy usage is provided. It can be concluded that the model can estimate the battery lifetime under different testing scenarios with an error rate less than 5 %.

A three-port power divider consisting of a directional coupler, a Wilkinson power divider, and two transmission lines connected to them is proposed. Theoretical analysis reveals that highly unequal power division can be achieved by a feedback mechanism of two transmission lines along with the coupling coefficient of the directional coupler and the power division ratio of the Wilkinson power divider. The three-port power divider inherits the performance characteristics of high isolation, low reflection coefficients at all ports, and the minimum number of components. The proposed power divider is designed at 5.8 GHz and fabricated and evaluated through measurements. It demonstrates that electromagnetic simulation results are in good agreement with theoretical prediction and measurement results. The three-port power divider is compact in the planar form, so it can be easily integrated into radio frequency front ends.

The diversity of wireless networks and protocols used by Internet of Things makes solutions non-interoperable. Moreover, some Things are not always able to communicate due to resource constrains or environmental factors. In this paper, those issues are addressed by introducing the concept of virtual Things. It means that each real Thing is virtualized in a local server or in the cloud, enabling communication with the user through a common protocol, i.e., the Internet Protocol. The virtual Thing has its own Internet Protocol address and authentication measure to control the access.

In this work, we design and fabricate a wireless system with the main operating device based on zinc oxide (ZnO) nanowires. The main operating device is based on piezoelectric nanogenerator (NG) achieved using ZnO nanowires grown hydrothermally on paper substrate. The fabricated NG is capable of harvesting ambient mechanical energy from various kinds of human motion, e.g., footsteps. The harvested electric output has been used to serve as a self-powered pressure sensor. Without any storage device, the signal from a single footstep has successfully triggered a wireless sensor node circuit. This study demonstrates the feasibility of using ZnO nanowire piezoelectric NG as a low-frequency self-powered sensor, with potential applications in wireless sensor networks.

This article intends to answer the question how to achieve wireless data rates that can catch up with current Internet speed, from a basic physics point of view. It is shown that the traditional electric circuit theory and design methodology that have been used for generations are unfortunately not adequate for wireless communications in the future. Instead, disruptive approaches such as six-port modulators for processing of electromagnetic waves and optical pulses should be employed to push up the wireless data rate above 100 gigabits per second. The key variables to consider for high speed digital communications are bandwidth, modulation order and signal-to-noise ratio. In principle, it should be possible to achieve a wireless data rate at 100 Gbps within the frequency spectrum below 20 GHz.

Results from our recent study on six-port modulators and demodulators for high speed data transmission have shown that the six-port radio technology has the potential to catch up the speed of the Internet. This is due to the fact that the binary baseband data, either electrical or optical, can be converted directly to high order modulated RF signal without any D/A conversion. The six-port modulators and demodulators can also be designed with differential circuitry to improve the signal-to-noise ration and dynamic range. In addition, antennae and radio front-end components can be integrated on the same substrate with the six-port modulator and demodulator.

If present, nonlinear effects in a six-port modulator cause distortion and degradation of the quality of the modulated output waveform. How nonlinear effects occur and their impact on system performance were derived in a mathematical model. The model shows that non-ideal performance of the passive six-port correlator is the main contributor to nonlinear distortion. Simulations and measurements on two manufactured six-port modulators were used to validate the theory and to give deeper insight on system performance. It is shown that by using a differentially signaled six-port modulator instead of a single-ended six-port modulator, better performance is achieved over a wide bandwidth. For an error vector magnitude of less than 10%, the relative bandwidth was measured to 12% for the single-ended but 30% for the differentially signaled modulator

A wireless sensor network was used to automatically control the life-support equipment of a green wall and to measure its influence on the air quality. Temperature, relative humidity, particulate matter, volatile organic compound and carbon dioxide were monitored during different tests. Green wall performance on improving the air quality and the influence of the air flow through the green wall on its performance were studied. The experimental results show that the green wall is effective to absorb particulate matter and volatile organic compound. The air flow through the green wall significantly increases the performance. The built-in fan increases the absorption rate of particulate matter by 8 times and that of formaldehyde by 3 times.

A method to implement quantized-state system (QSS) models in industry standard RF-IC design tools is proposed. The method is used to model a GHz-range 0.18 um CMOS phase-locked loop (PLL), and enables a truly event-driven simulation of the entire mixed-signal PLL circuit. First- and second-order (QSS and QSS2, respectively) models of the PLL loop-filter implemented in Verilog-AMS are first described in detail. These models do not rely on analog nets, and use only the event-based solver. Then, simulation results are compared to reference SPICE simulation results to prove the validity of the QSS method. The entire PLL circuit is finally simulated using the QSS model of the loop-filter, charge-pump and VCO, in conjunction with standard high-level models of the PLL digital circuits. To verify the proposed QSS method, measured phase noise is compared with simulated phase noise. It is shown that simulated phase noise accurately predicts the measured phase noise with improved accuracy, and an increase in simulation efficiency by more than 50 times. Measured and simulated results generally demonstrate the feasibility of the QSS modeling for mixed-signal circuit simulation and design.

A frequency diplexer network for ultrawideband radios focused on wireless parallel data transmission is presented. It has a combination of two bandpass filters utilizing manifold multiplexing technique. In the frequency band 6-9 GHz, two flat sub-bands at center frequencies 6.7 and 8.3 GHz have been achieved with respect to forward transmission, input reflection, and group delay. A maximum group delay variation of 0.6 ns was measured in the sub-bands. For low cost and simple circuit implementation, the design is implemented using the microstrip technology.

This paper presents the design and implementation of a web-based wireless indoor climate control system. The user interface of the system is implemented as a web service. People can login to the website and remotely control the indoor climate of different locations. A wireless sensor network is deployed in each location to execute control commands. A gateway is implemented to synchronize the information between the wireless sensor network and the web service. The gateway software also includes scheduling function and different control algorithms to improve the control result. Additionally, the system security and availability are highly considered in this system. The gateway software implements a warning function which sends warning messages when emergency happens. Finally, the whole wireless control system architecture is modularly designed. It is easy to add different control applications or different control algorithms into the system.

As defined by the ZigBee standard, a router should be mains-powered in order to maintain the mesh feature of the ZigBee network. This study presents a method which allows the ZigBee router goes into sleep mode periodically and keeps the same mesh feature during the ZigBee communications. In this study, the standard ZigBee communication is separated into two synchronized clusters. The first cluster includes the communication between end devices and the associated router. The sensor message report time of different end devices are scheduled by the router in different collision-free time slots within a predefined time interval. The second cluster includes the mesh communication between routers and the concentrator. All routers are synchronized so that they wake up at the same time to maintain the mesh feature. In order to maximize the router battery lifetime, algorithms are developed so that the concentrator communicates with routers according to the network routing records. Additionally, in order to recover the broken communication, special logics are implemented in routers and end device so that they can rejoin the wireless sensor network with low power consumption. Finally, a battery lifetime model is presented which can be utilized to calculate battery lifetime of the ZigBee router under different network configurations.

A compact size six-port correlator using bandwidth enhancing stubs for the 69 GHz ultra wideband radio is presented. The proposed six-port has a center frequency of 7.5 GHz with 50% relative bandwidth. The correlator is based entirely on microstrip technology for low cost and simple circuit implementation.

A 3600-MHz phase-locked loop based frequency synthesizer for UMTS applications has been developed in 0.18 $mu$ m CMOS. It incorporates a VCO frequency and loop-gain calibration technique that allows an integrated VCO frequency tuning range of 28% and a low VCO gain ($K_{rm VCO}$ of 30 MHz/V. The loop-gain calibration can compensate for not only variations in VCO gain and divider modulus, but also charge-pump current and loop filter capacitance to an accuracy of 5%. The PLL settles in 150 $mu$s including frequency and gain calibrations. No switches are used in the loop filter. The output phase noise at 1-MHz offset is ${-}123$ dBc/Hz and the integrated phase error (1 kHz–2 MHz) is 1.26 $^{circ}$.

A triplexer for ultra-wideband radio implemented entirely with distributed microstrips is presented. The triplexer is composed of a triplex junction network and three bandpass filters. The circuit is integrated in a flex-rigid printed circuit board. Three flat 1 GHz sub-bands in the frequency band 6-9 GHz have been achieved. The group delay variation within each 1 GHz sub-band was measured to be less than 0.4 ns. A good agreement between simulation and measurement was obtained, e.g., less than 0.3 dB difference in the forward transmission in the majority of the frequency band.

A new circuit architecture for a direct-carrier six-port modulator is proposed. The proposed architecture uses parallel binary-valued baseband signals to control binary-valued impedance loads for generation of rectangular M-QAM modulation. A theoretical model of the proposed modulator is also derived. A prototype modulator for 64 quadrature amplitude modulation is designed and fabricated for a center frequency of 2.5 GHz for verification of the proposed architecture. The measurements verify the theory and show that good performance can be obtained with the proposed architecture. The proposed modulator does not require any digital-to-analog converter and can operate with both electrical and optical control signals.

The use of six-port correlators to implement six-port receivers has been intensively studied. The six-port receiver can also be modified to a five-port or a four-port receiver. However, the six-, five-, or four-port receiver solution requires different baseband processing to recover the baseband In-phase (I) and Quadrature-phase (Q) data. A unified mathematical model for the six-, five- and four-port receivers is presented in this article. Possible solutions to recover the baseband data are discussed and compared. The investigation shows that the six-port receiver has advantages over the five- and four-port receivers in terms of complexity when analog baseband processing is used. Simulations are conducted to verify the model and to estimate the error vector magnitude versus frequency; the simulation also shows that the six-port receiver operates over a wider bandwidth than the five- or four-port receiver.

In six-port modulators a phase shifting network on specific ports can be used to suppress the carrier leakage that may be present if this network is not present. A model is derived to predict the carrier leakage suppression and error vector magnitude (EVM) as a function of the phase shifting network Sparameters. Both carrier leakage suppression and EVM can be expressed by the same error function. The error function can be used to find the allowed amplitude and phase mismatch in the phase shifting network, or to optimize the performance of a phase shifting network over a given frequency range. A broadband phase shifting network, based on a loaded transmission line, is designed and optimized to operate at a relative bandwidth of 60% for an EVM < 10%. This should be compared to a phase shifting network based on a single transmission line with a corresponding bandwidth of only 12%. The broadband phase shifting network is useful for six-port modulators with carrier leakage suppression, targeting UWB applications.

This paper presents an innovative MIMO antenna system consisting of two broadband antennas combined with a 90° or 180° hybrid coupler. The antenna system is suitable for future MIMO systems due to its wide decoupled bandwidth (from 698 to 2700 MHz) covering 23 frequency bands of LTE. Enhanced antenna performance is achieved by radiator slitting and ground plane modification. Moreover, supplemental meandered line ground structures are utilized to miniaturize the antenna size. The low profile antenna with its wide impedance bandwidth, high efficiency, low correlation and quasi-omni directional radiation pattern is attractive for the existing and future 4G mobile communication devices. Simulated and measured results including input reflection, mutual coupling, correlation, and antenna efficiency is presented and analyzed.

Targeting the differential RF/microwave circuit design methodology for improved broadband wireless data transmission, a novel differential 7.5 GHz six-port modulator and demodulator pair was designed and manufactured. Measurements show a good 256-QAM modulated signal at 50 Msymbol/s and an accurately 16-QAM demodulated signal at 200 Msymbol/s.

In a six-port demodulator utilizing diodes for power detection, impedance mismatch at the interface between the six-port correlator and diodes generates unwanted local oscillator (LO) leakage to the radio frequency (RF) port. A six-port modulator that uses variable reflection coefficients at specific ports to generate a modulated RF may also suffer from LO leakage if there is a static part in the reflection coefficient. It is known that LO leakage to the RF port not only generates unwanted emission of the LO signal, but also degrades the receiver system performance due to a dynamic dc offset and second-order non-linearity at the detected baseband signal. How this LO leakage appears to the RF port in six-port demodulators and modulators are analyzed. Two different approaches to suppress the LO leakage is then discussed: a) diode impedance matching and b) introduction of a λ/4 line on specific ports. The performance when λ/4 lines are used on specific ports is verified by measurement for both a demodulator and a modulator. The measurement shows high suppression of the LO leakage.

This paper presents the methods for the ZigBee network reliability enhancement and the battery life time optimization. The paper begins with the introduction of the common communication problems due to the broken links between sensor module and message relay, or between different relays. Extra message hand shake mechanisms are added to solve different problem mentioned at the beginning. Finally, a general purpose reliability enhancement component is developed as a state machine which can be work together with ZigBee protocol to enhance ZigBee network communication reliability. Moreover, the battery life time of the sensor module during link broken is considerably increased after the enhancement.

This paper presents a component based wireless monitoring and control system. The system is introduced from both the system architecture and function point of view. The paper begins with the introduction of the component design and the communication interaction between them. The system is composed by three components, the wireless sensor network, the local server and the main server. Wireless sensor networks are deployed in different locations for remote monitoring and control purpose. The monitoring results and control commands are synchronized between the main server and wireless sensor networks via local servers. The test results of the battery life time calculation and remote monitoring field test results are presented in the end of the paper.

A differential six-port demodulator for the 7-8 GHz band is reported for the first time. It is composed of a differential six-port correlator on the two sides of the substrate and zero-bias antiparallel Schottky diodes acting as power detectors. It is theoretically analyzed and also simulated. A prototype has been fabricated and data transmission at 0.8 Gbit/s (but not the maximum) with the 16 quadrature amplitude modulation (QAM) is experimentally demonstrated.

A differential six-port demodulator for the 7-8 GHz band is reported for the first time. It is composed of a differential six-port correlator on the two sides of the substrate and zero-bias antiparallel Schottky diodes acting as power detectors. It is theoretically analyzed and also simulated. A prototype has been fabricated and data transmission at 0.8 Gbit/s (but not the maximum) with the 16 quadrature amplitude modulation (QAM) is experimentally demonstrated.

A differential six-port modulator for the 7-8 GHz band is reported for the first time. It is composed of a differential six-port correlator with cold-mode field effect transistors used as impedance terminations, controlled via baseband signal on the gate to source terminal. It is fabricated using double-sided parallel-strip lines. The differential modulator has the advantage of low power consumption, compactness and high signal to noise ratio. A prototype has been fabricated and data transmission with 256-quadrature amplitude modulation at 50 Msymbol/s is demonstrated. © 2011 IEEE.

A fully integrated dipole antenna with a balun fot ulna wideband (UWB) radio in the band 6-9 GHz utilizing a flexible and rigid printed count board is presented in this at tide The balun utilizes broadside coupled microstrips and is integrated in the rigid part of the printed coma boat d whereas the radiator is placed in the flexible pat! The antenna with the balun covets the frequency band 6 0-8 5 GHz at voltage standing mate ratio (VSWR) andlt;2 0 and 55-110 GHz at VSWR andlt; 2 5 Moreover simulated and measured radiation patterns and antenna efficiency above 860% are observed

This paper presents a direct carrier six-port modulator. To allow arbitrary load impedances to be used and for suppression of carrier leakage, a new circuit architecture with a technique to suppress carrier leakage is proposed and implemented. A theoretical model of the proposed modulator is derived. A prototype modulator utilizing diodes for impedance generation is designed and fabricated for a center frequency of 7.5 GHz for verification of the proposed technique. Measurements show good modulation properties when a 16 quadrature amplitude modulation signal at 100 Msymbol/s is generated, as well as good carrier leakage suppression.

In six-port modulators a phase shifting network on specific ports can be used to suppress the carrier leakage that may be present if this network is not present. A model is derived to predict the carrier leakage suppression and error vector magnitude (EVM) as a function of the phase shifting network Sparameters. Both carrier leakage suppression and EVM can be expressed by the same error function. The error function can be used to find the allowed amplitude and phase mismatch in the phase shifting network, or to optimize the performance of a phase shifting network over a given frequency range. A broadband phase shifting network, based on a loaded transmission line, is designed and optimized to operate at a relative bandwidth of 60% for an EVM < 10%. This should be compared to a phase shifting network based on a single transmission line with a corresponding bandwidth of only 12%. The broadband phase shifting network is useful for six-port modulators with carrier leakage suppression, targeting UWB applications.

The use of Schottky diodes as high-speed variable impedance loads in six-port modulators are proposed and analyzed in this paper. The impedance dependency of diode parameters and local oscillator power are investigated by theoretical analysis and simulations. A prototype for a direct carrier six-port modulator using Schottky diodes for impedance generation is designed and fabricated for a center frequency of 7.5 GHz. Measurements show good modulation properties when a 16 quadrature amplitude modulation signal at 300 Msymbol/s is generated, i.e., at a data rate of 1.2 Gbit/s, validating the use of Schottky diodes as high-speed variable impedance loads in six-port modulators.

This paper presents measurement results for a six-port-based demodulator designed for a center frequency of 7.5 GHz and with a bandwidth of 1 GHz for operation in the ultra-wideband band. The demodulator includes the six-port correlator, diodes, and amplifiers needed to recover the baseband data. Measurement results show that the prototype supports data rates at 1.7 Gbit/s with bit-error rate 5 . 10(-5) if a two-tap linear equalizer is used and bit-error rate 4 . 10(-3) if only threshold detection is used. The measured performance of the used six-port correlator including the amplifiers is presented and their influence on the overall system performance is discussed. Limitations in the present system and possible improvements are also considered.

A study of the component tolerances on an ultra-wideband low-noise amplifier designed on a conventional printed circuit board is presented in this paper. The low-noise amplifier design employs dual-section input and output microstrip matching networks for wideband operation with a low noise figure and a flat power gain. Firstly, the effect of passive component and manufacturing process tolerances on the low-noise amplifier performance is theoretically studied by means of sensitivity analyses. Secondly, simulation and measurement results are presented for verification of the analytical results. It is shown that, compared with a lumped matching network design, a microstrip matching network design significantly reduces the ultra-wideband low-noise amplifier sensitivity to component tolerances.

This paper proposes how antenna polarization can be utilized to increase the maximum data rate in a multiple six-port receiver system. By utilizing data and carrier interleaving, the total information bandwidth increases and therefore the maximum data rate. Prototype antennas were manufactured and the measured results were later used in a simulation model with three channels for verification of the concept.

A wireless solution of remote climate control for cultural buildings is presented in this paper. The system allows users to use web service to control climate in different cultural buildings, like churches. The wireless sensor networks deployed in churches receive the control commands and manage the indoor climate. The whole system is modularly designed, which makes possible an easy service extension, system reconfiguration and modification. This paper includes the system overview and the software design of each part within the system.

This paper presents two new diode configurations for use with six-port based demodulators. The first proposed diode configuration allows a simplified diode to filter/amplifier interface. The second configuration allows for full-wave rectification and suppression of odd-order harmonics. A demodulator prototype utilizing the new diode concept is designed for a center frequency of 7.5 GHz and with a bandwidth of 1 GHz for verification. The demodulator includes the six-port correlator, diodes and amplifiers needed to recover the baseband data.