Integrated Antenna Research Articles

Energy Efficiency in IoT Networks: Integration of Reconfigurable Antennas in Ultra Low-Power Radio Platforms Based on System-on-Chip

The current state-of-the-art of Internet of Things witnesses the development of low-cost and smart-connected wireless sensor networks (WSNs) placed at the edge of clouds, enabling new services over the Internet. In these interconnected smart sensors, energy consumption is an important issue. This paper deals with decreasing energy consumption in WSN nodes by means of antennas with reconfigurability at radiofrequency. Our research has yielded two important novelties. First, the reconfiguration is accomplished with a platform comprised of a commercial ultra low-power (ULP) micro-controller and system-on-chip radio. Second, we consider explicitly the energy overhead involved in the antenna configuration process and its impact on the global energy efficiency of the system. We discuss two complementary ways of reducing the energy consumption; one by lowering the amount of transmitted power, the other by increasing the transmission rate. We employ an antenna array with a steerable beam, controlled by an algorithm embedded in the firmware of the ULP platform. This is designed for line-of-sight conditions, and the beam steering maximizes the received power. Our results show that with a common IEEE 802.11 b/g system-on-chip module and an antenna gain of 12 dB, a net power saving factor of 28% can be obtained by reducing the transmitted power, at unchanged data rate; additionally, by keeping the transmit power constant, but increasing the data rate, an energy saving from 18% to 96% can be achieved, depending on the link distance and achievable data rate. Our experiments have confirmed both routes of energy saving.

An Integrated Shark-Fin Antenna for MIMO-LTE, FM, and GPS Applications

A roof automobile antenna for Long Term Evolution, navigation system, and frequency modulation (FM) applications is presented. The proposed antenna is installed in shark-fin housing on the roof of a car, which includes a 4G (the fourth generation mobile communication system) main antenna, 4G diversity antenna, navigation antenna, and FM antenna. Some miniaturization and multiband techniques are utilized to fit the available space of the shark-fin housing, such as the grounded and parasitic radiating elements, meandered radiating elements, and lumped elements. It is worth noting that the proposed 4G main antenna with a compact size of 55 mm × 25 mm × 2 mm can cover two wide bands including 698–960 MHz and 1710–2690 MHz. Both the main antenna and diversity antenna have omnidirectional radiation patterns in the azimuthal plane. All the designs are planar printed antennas fully integrated into the printed circuit board, which significantly reduces the cost. The simulation and measurement results are in good agreement.

A Compact Rx Antenna Integration for 3D Direction-Finding Passive Radar

A Compact Rx Antenna Integration for 3D Direction-Finding Passive Radar

Design of Compact MEMS Antenna Based on Photonic Crystal Structure

The miniaturized and integration antenna is designed to utilize high dielectric constant silicon substrate. Because of the inverse relation between planar size and dielectric constant, the proposed silicon antenna has very compact planar size. In order to enhance radiation efficiency of silicon antenna, the design method of photonic crystal antenna is proposed by applying periodical triangular lattice. Three dimensional MEMS manufacturing technology is used to fabricate the proposed antennas by photoetching, ICP through-hole etching and bonding processes, which can accurately realize cavity, air through-holes and other subtle and complicated structures. The experiment results demonstrate the MEMS antenna can obviously extend working bandwidth and improve radiation gain of the original antenna based on two dimensional triangle lattice photonic crystal structure.

A Wirelessly Powered Injection-Locked Oscillator With On-Chip Antennas in 180-nm SOI CMOS for Spectroscopy Application

We present a wirelessly powered millimeter-sized injection-locked oscillator with on-chip antennas for material spectroscopy application. The main challenge is to design an efficient and sensitive wireless energy-harvesting front-end with integration of an on-chip antenna and a wide locking range oscillator. The on-chip antenna receives electromagnetic energy from a continuous-wave source in the X-band frequency. A superharmonic injection-locking oscillator locks to the frequency of the input and produces a synchronized signal at half the frequency of the input. This new signal is then radiated back using an on-chip dipole antenna, which resolves the conventional self-interference issue in radio-frequency identification (RFID) sensors. In addition, the locking mechanism improves the phase noise of the on-chip oscillator to -93 dBc/Hz at 100 Hz offset. The large locking range of the transmitting signal shows promising results for spectroscopy applications, which can be used for material detection and analysis.

Far-Field-Based Nonlinear Optimization of Millimeter-Wave Active Antenna for 5G Services

This paper presents the design and characterization of millimeter-wave (28/38 GHz), circularly polarized (CP) active antennas, suitable for future 5G services. By augmenting the modeling capabilities of commercially available nonlinear CAD tools, the active antenna design can simultaneously optimize figures of merits for both radiation and nonlinear (NL) performance. The radiating part is computed and optimized layoutwise by means of an artificial neural network (ANN), suitably trained off-line. For the NL design purpose, the harmonic neural network (HNN) of the antenna is subsequently implemented as a standard circuit component, to include the antenna behavior at all the harmonics of its NL regime. This allows avoiding time-consuming electromagnetic (EM)-simulations in the harmonic balance optimization loop. In this way, a well-defined interface between the antenna and the amplifier can be avoided. To demonstrate the effectiveness of the design approach, one active integrated antenna (AIA), consisting of a class AB amplifier feeding a CP patch at 38 GHz, has been fabricated with the standard 0.1- $\mu \text{m}$ AlGaAs-InGaAs pHEMT technology and extensively measured with respect to both the electrical and radiation performances. To reduce fabrication costs, hybrid integration of the antenna and amplifier connection is used, and the antenna is incorporated into the main PCB.

A Bond Wire Connection Implementation at mm-Wave Active Microstrip Antenna

A bond wire to microstrip line transition, featuring two impedance transformers, is presented for a mm-wave microstrip antenna and power amplifier (PA) integration using conventional bond wires. Simulated return loss bandwidth for the transition is 4 GHz with a minimum insertion loss of 1 dB. Measurement results for the designed active antenna are compared with measurements for a passive antenna and a standalone PA. The maximum gain is 29 dBi, compared with 16.7-dBi passive antenna maximum gain. The half-power gain bandwidth is 7%. The measured active antenna radiation pattern is in good agreement with simulations. The maximum deembedded PA output power is close to 9 dBm.

Design of the Photonic Crystal Slot Fractal Array Ultra Wideband Antenna

According to the performance requirements of the multi band compatible antennas for the mobile communication system, the radio frequency identification system, the ultra wideband system and the mobile digital TV system, the present paper originally combined photonic crystal structure, embedded slot fractal, rectangular array antenna, relative dielectric constant gradual thin film, potassium tantalum niobate thin film, Fe-based nanocrystalline alloy coating and graphene conductive ink, and designed a photonic crystal slot fractal array ultra wideband antenna. The result of test indicates that this antenna has strong anti-EMI capability, large performance redundancy and ultra wideband operation capability. This antenna completely covered all working frequency bands of the second generation to the fifth generation mobile communication, the frequency bands of the radio frequency identification system, the frequency band of the ultra wideband system, and the frequency band of the mobile digital TV system. This antenna has small size, high radiation intensity, stable and reliable operation performance; it is a microwave band multi network integration antenna with excellent performance.

Contact-Less Near-Field Test of Active Integrated RF Phased Array Antennas

Future RF transceivers are expected to integrate the entire system, from baseband to antenna. Many emerging applications use beam forming, which necessitates RF phased arrays and multiple antennas integrated on the same die. This integration presents a challenge in testing the entire system including antennas. The electromagnetic signal output is combined in the air and no longer can be separated by physically connecting to the test equipment. Testing each element in isolation does not exercise the interaction between the elements and cannot characterize important parameters such as phase mismatch. Thus, systems with multiple integrated antennas need to be tested using wireless means. This paper presents a novel contact-less near-field test method for measuring the gain and phase mismatch of RF phased array antennas. The proposed method is based on using a known good die (KGD) receiver phased array antenna to capture the combined EM output of the transmitter antenna as the device under test (DUT). The mathematical model of mutual impedances and signal propagation is presented for a 16-element phased array to determine both gain and phase mismatches. The feasibility of the method is shown using hardware measurement. The accuracy of the method under process variations and imperfections in the test set-up, including noise and error in test set-up dimensions, is further investigated through electromagnetic (EM) simulations of a coplanar patch antenna array of sixteen elements.

Enhancement of Photocurrent by Integration of an Artificial Light-Harvesting Antenna with a Photosystem I Photovoltaic Device

Photosynthetic pigment–protein-based biophotovoltaic devices are attracting interest as environmentally friendly energy sources. Photosystem I (PSI), a photosynthetic pigment–protein, is a proven biophotovoltaic material because of its abundance and high charge separation quantum efficiency. However, the photocurrent of these biophotovoltaic devices is not high because of their low spectral response. We have integrated an artificial light-harvesting antenna into a PSI-based biophotovoltaic device to expand the spectral response. To fabricate the device, a perylene di-imide derivative (PTCDI) was introduced onto a TiO2 surface as an artificial antenna. In the photovoltaic cells formed by the PTCDI/PSI-assembled TiO2 electrode, the magnitude of the incident photon-to-current conversion efficiency spectrum was significantly enhanced in the range 450–750 nm, and the photocurrent increased to 0.47 mA/cm2. The result indicates that the photons absorbed by PTCDI transfer to PSI via Forster resonance energy transfer.

Wirelessly-Powered Dielectric Sensor With On-Chip Antennas in 180 nm SOI CMOS Process

This paper presents a battery-less mm-sized wirelessly-powered dielectric sensor with on-chip antennas in 180nm SOI CMOS process. The dielectric constant detection is achieved by sensing capacitance change of a capacitor in an oscillator, which causes a shift in the oscillation frequency. The chip harvests electromagnetic energy from a continuous-wave source at 9.8 GHz using an on-chip antenna, which shrinks the whole sensor size to millimetre scale. The design details of the wireless power transferring front-end with integration of an on-chip antenna are reported. The oscillator free-running frequency is from 3.66 to 4 GHz which depends on the material on top of the chip. The chip radiates back the signal to an external reader antenna. This frequency division architecture resolves the conventional self-interference issue in radio frequency ID sensors by separating the received and transmitted frequencies. The detection of oil and epoxy is successfully demonstrated.

Fast Start-Up RF Energy Harvester Design for GSM-900 Uplink Band

In this brief, a co-design and integration of rectifier, antenna, and matching network are introduced in order to obtain a fast harvester with sufficient bandwidth to capture energy of the activity-dependent GSM-900 uplink signals. A tunable two-state matching network is proposed to improve the transient response of the harvester. A complete harvester comprising of a Schottky diode rectifier, small patch antenna and the proposed two-state matching network is designed and fabricated. Measurements show that the proposed matching network compared to the traditional fixed matching can result in about a 20% reduction in the charging time of the harvester for input available power of −10 dBm.

Photonic-based integrated sources and antenna arrays for broadband wireless links in terahertz communications

This paper analyzes integrated components for ultra-broadband millimeter-wave wireless transmitters enabling the 5 G objective to increase the wireless data rates 10× to 100×. We have pursued the photonic-based approach to generate the millimeter-wave carrier (≈97 GHz in this paper) through photomixing. We have achieved up to 10 Gb s−1 data rate using an OOK modulation format (to reduce latency) and either direct detection (DD) or coherent detection. We show that coherent detection enables a sensitivity improvement of 17 dB over DD. We also demonstrate in this work that such improvement can be achieved using as the transmitter a novel integrated antenna array—the self-complementary chessboard array. This avoids the use of complex coherent schemes at the receiver, enabling simple DD for ultra-broadband links.

A Compact Planar Omnidirectional MIMO Array Antenna With Pattern Phase Diversity Using Folded Dipole Element

This paper presents a planar omnidirectional multiple-input multiple-output (MIMO) antenna with pattern phase diversity. The profiles of conventional dual-polarized omnidirectional MIMO antennas are too high to be planar integrated due to the limited bandwidth of vertical-polarized element. Therefore, a dual-channel horizontal-polarized MIMO antenna is proposed for the planar integration of omnidirectional MIMO antenna. The antenna is formed with four-element folded dipole array, and a compact feed network with two sets of 90° progressive phases is employed to feed the two channels with shared elements, thus the antenna can be integrated into a sheet of substrate with an ultralow profile of 0.8 mm. Although the polarization and radiation pattern (amplitude) of the two colocated channels are the same with each other, a high isolation is still achieved as a result of the orthogonal pattern phase. A prototype was fabricated to validate the performance. The measured highest isolation between two channels is 31.7 dB, and −10 dB isolated bandwidth is 2.29–2.57 GHz (11.7%) with S11 < −14 dB and envelope correlation coefficient less than 0.05, which shows a good diversity performance. Therefore, the proposed dual-channel antenna gives a feasible solution for the planar integration of the omnidirectional MIMO system.

An Integrated Radar Tile for Digital Beamforming X-/Ka-Band Synthetic Aperture Radar Instruments

This paper presents the first experimental assessment of a highly integrated dual-band dual-polarized antenna tile designed for synthetic aperture radar (SAR) digital beamforming (DBF) satellite applications. The demonstrator described in this paper is the first comprehensive experimental validation of an RF module providing the X-band and Ka-band (9.6- and 35.75-GHz) operation with custom downconversion stages. All the antennas, transitions, and downconversion chips are integrated in the same antenna tile fabricated using a customized 15-layer high density interconnect process. The designed tile goes to the limits of the proposed technology and for the high trace density and for the size of the vertical transitions. The proposed results represent the state of the art in terms of compactness for a DBF SAR RF module even though the demonstrator was manufactured with a standard low-cost technology. The experimental assessment proves the validity of the proposed manufacturing and integration approaches showing a substantial agreement between the performance of the individual blocks and of the integrated system.

Investigation of Antennas Integrated Into Disposable Unmanned Aerial Vehicles

The integration of antennas into disposable paper drones using inkjet printing technology is presented. These drones or unmanned aerial vehicles (UAVs) are developed using origami folding structures. Two vertical monopole antennas based on the same design concept are proposed and their performance assessed for two different conditions. The conditions relate to the placement of the other electronic components and circuits on the origami drones as reported in the literature. The first is when the electromechanical components and corresponding metallic layers are located in the wings. In this case, the effect of the possible location of the antenna as well as the deformation of the wings on S11 is discussed. The second is a more general case scenario which includes when the components and motors are placed at the tail and lower part of the body of the drone. The antenna elements are directly printed onto a photo paper substrate using silver nanoparticle conductive ink. Subsequently, the substrate is folded to create a paper drone. Low-cost desktop inkjet printing equipment is used to deposit the metallic tracks of the antenna. The designs target the current frequency bands employed in the control and wireless communication of commercial drones (2.4 GHz and 5 GHz bands). The purpose of this work is to investigate potential antenna scenarios for disposable drones which may one day be fully fabricated using inkjet printing technology. All antenna designs and studies have been simulated using CST Microwave Studio and compared well with experimental results.

Design of patch active electronically scanned antenna for 5G communication system

The article deals with the research and design results of an active electronically scanned antenna (AESA) based on beamforming BiCMOS monolithic integrated circuit (MIC) and patch antenna radiators. The operating frequency band is sub-6 GHz. MIC design is at the stage of transferring files to the manufacture and verification of integrated circuit parameters. In this regard, the current task is the antenna radiators design, that is the main focus of this paper.

Challenges in On-Chip Antenna Design and Integration With RF Receiver Front-End Circuitry in Nanoscale CMOS for 5G Communication Systems

This paper investigates design considerations and challenges of integrating on-chip antennas in nanoscale CMOS technology at millimeter-wave (mm-wave) to achieve a compact front-end receiver for 5G communication systems. Solutions to overcome these challenges are offered and realized in digital 28-nm CMOS. A monolithic on-chip antenna is designed and optimized in the presence of rigorous metal density rules and other back-end-of-the-line (BEoL) challenges of the nanoscale technology. The proposed antenna structure further exploits ground metallization on a PCB board acting as a reflector to increase its radiation efficiency and power gain by 37.3% and 9.8 dB, respectively, while decreasing the silicon area up to 30% compared to the previous works. The antenna is directly matched to a two-stage low noise amplifier (LNA) in a synergetic way as to give rise to an active integrated antenna (AIA) in order to avoid additional matching or interconnect losses. The LNA is followed by a double-balanced folded Gilbert cell mixer, which produces a lower intermediate frequency (IF) such that no probing is required for measurements. The measured total gain of the AIA is 14 dBi. Its total core area is 0.83 mm 2 while the total chip area, including the pad frame, is 1.55 × 0.85 mm 2 .

Low-Cost Polarization Sensing System for Self-Oscillating Circularly-Polarized Active Integrated Antenna

A simple, low-cost yet efficient polarization sensing system, capable of determining the polarization state of a self-oscillating circularly-polarized active integrated antenna (CPAIA), is proposed and demonstrated. The newly developed sensing system is capable of retrieving the phase difference information between the orthogonal field components of a CPAIA without the need of a common synchronous reference signal as that in a conventional pattern measuring system. The two orthogonal electrical fields are captured and mixed to retrieve the relative phase difference information as dc voltages. As a proof of concept, the polarization sensing system has been successfully developed on a printed circuit board, while a typical passive circularly-polarized antenna and a self-oscillating CPAIA were fabricated as a pair of antennas under test (AUTs). On one hand, the passive AUT characterized by the sensing system was supported by data from a commercial measuring setup to validating the accuracy of the newly developed system. On the other hand, the proposed sensing system is believed to be the first demonstration dedicated to retrieving the polarization information of a self-oscillating CPAIA, and hence pave a new way to fully characterize this special sort of active antennas.

Design and performance analysis of broadband rectenna for an efficient RF energy harvesting application

This article proposes the design of coplanar waveguide (CPW) fed broadband rectenna for radio frequency (RF) energy harvesting application. The rectenna is designed to operate in the industrial, scientific, and medical (ISM) frequency band of 5.8 GHz. For designing the proposed rectenna, polytetrafluoroethylene (PTFE) dielectric material was used to design, fabricate the CPW fed slot antenna. It was observed that the proposed antenna exhibits the |S11| of −23.43 dB and achieves the peak antenna gain of 8.56 dBi at 5.8 GHz. Secondly, the CPW fed rectifier circuit which comprises of the matching circuit, rectifying unit, and filter was designed. The measured results showed that the |S11| of −19 dB and it was perfectly matched with 50 Ω impedance. Finally, the rectenna was designed by integration of antenna with rectifier circuit. The simulated results showed the maximum RF to direct current (DC) conversion efficiency and the output DC voltage of 88% and 445 mV at the load resistance of 1 kΩ. The measured results show the maximum RF to DC conversion efficiency of 73.4% with the output DC voltage of 540 mV at the load resistance of 1 kΩ.