Effective Isotropic Radiated Power Research Articles

A Self-Powered UHF Passive Tag for Biomedical Temperature Monitoring

Self-powered RF passive sensors have potential application in temperature measurements of patients with health problems. Herein, this work presents the design and implementation of a self-powered UHF passive tag prototype for biomedical temperature monitoring. The proposed battery-free sensor is composed of three basic building blocks: a high-frequency section, a micro-power management stage, and a temperature sensor. This passive temperature sensor uses an 860 MHz to 960 MHz RF carrier and a 1 W Effective Isotropic Radiated Power (EIRP) to harvest energy for its operation, showing a read range of 9.5 m with a 13.75 µW power consumption, and an overall power consumption efficiency of 10.92% was achieved. The proposed device can measure temperature variations between 0 °C and 60 °C with a sensitivity of 823.29 Hz/°C and a standard error of 13.67 Hz/°C over linear regression. Circuit functionality was validated by means of post-layout simulations, characterization, and measurements of the manufactured prototype. The chip prototype was fabricated using a 0.18 µm CMOS standard technology with a silicon area consumption of 1065 µm × 560 µm. The overall size of the self-powered passive tag is 8 cm × 2 cm, including both chip and antenna. The self-powered tag prototype could be employed for human body temperature monitoring.

Compact Ring Antennas With High-Impedance Line Loaded With Distributed Inductors for On-Metal Tag Design

Two compact ultrahigh-frequency (UHF) tag antennas, which consist of a square ring loaded with two distributed inductors, are proposed for on-metal applications. Miniaturization of the antenna footprint is realized through the incorporation of two distributed inductors. It will be shown that the required inductances are much dependent on their locations on the ring resonator due to the variation of the current intensity. Due to the high-inductive nature of the distributed inductor, the antenna resistance of the ring resonator can be significantly enhanced so that it can achieve a conjugate impedance match with the microchip. A detailed analysis has been performed to understand the resonance characteristics, and transmission line models have been constructed for designing the tag antennas. Due to the significant improvement in the impedance matching, the proposed miniature tag antennas can achieve a far read distance of greater than 9 m on metal when they are tested with an effective isotropic radiated power (EIRP) of 4 W. Important to mention is that the tag resonant frequencies of the proposed tag antennas are stable and they are not affected much by the backing metallic objects.

A 0.45-THz 2-D Scalable Radiator Array With 28.2-dBm EIRP Using an Elliptical Teflon Lens

This article presents a novel coherent, scalable radiator array achieving the highest effective isotropic radiated power (EIRP) and highest dc-to-terahertz (THz) efficiency among silicon-based scalable THz sources beyond 400 GHz through co-design and optimization methods of the THz power generation and radiation. First, a 4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 4 slot antenna array with silicon substrate loading is optimized for high radiation efficiency and good radiation pattern without silicon lens. A low-cost Teflon lens is introduced and effectively illuminated by the radiator achieving a highly directive beam. Second, a novel 2-D scalable coupled harmonic oscillator array is proposed as the excitation network to feed the antenna array. The oscillator is optimized for the second-harmonic generation to provide high output power and efficiency. The chip is fabricated in a 65-nm CMOS process, and the core area of the chip is 0.55 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The radiated power of −2.4 dBm and 8.8-dBm EIRP are achieved at 449.8 GHz with 373-mW dc power consumption and 0.16% dc-to-THz efficiency under 1.2-V supply voltage. By adding an elliptical Teflon lens, 28.2-dBm EIRP is measured at 452.3 GHz under 1.2-V supply voltage, and a maximum EIRP of 29.1 dBm is measured at 458.3 GHz with 1.4-V supply voltage. By changing the bias and supply voltages, a 4.6% frequency tuning range is achieved. At 452.3 GHz, the measured phase noise is −76.4 dBc/Hz at 1-MHz offset.

Active and Passive Components for Broadband Transmit Phased Arrays: Broadband Transmit Front-End Components

Phased-array antennas have penetrated a large application space, and in this article, we present some of the critical components for phased-array front ends, as described in <xref ref-type="fig" rid="fig1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Figure 1</xref> . We focus on an octave-bandwidth 6- to 12-GHz transmit implementation, but the methodology and component designs are scalable in frequency. Over the past few decades, phased-array applications have expanded from radar to wireless and satellite communications, as well as medical imaging and various sensing modalities. By tracking users with individual high-gain beams, spatial multiplexing enables cochannel interference mitigation, enhancing signal levels, and power management in wireless communications systems. For example, <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> shows a 64-element phased-array transceiver operating in the 28-GHz band with 52-dBm effective isotropic radiated power (EIRP) for 5G applications with up to 12 Gb/s of throughput, and <xref ref-type="bibr" rid="ref2" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[2]</xref> demonstrates a system-level development of a 384-element, 16-tile, W-band phased array with 52-dBm EIRP in 0.18-μm silicon–germanium bipolar CMOS (BiCMOS) technology. In satellite broadcasting and communication systems, phased-array antennas enable beam shaping over countries and continents, tracking at the end-user side, and rain fading mitigation, e.g., <xref ref-type="bibr" rid="ref3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[3]</xref> . In <xref ref-type="bibr" rid="ref4" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[4]</xref> , advances in phased arrays for satellite applications developed at Lockheed Martin are described from an industry perspective.

TDS-1 GNSS reflectometry wind geophysical model function response to GPS block types

ABSTRACT This paper presents the TDS-1 GNSS reflectometry wind Geophysical Model Function (GMF) response to GPS block types. The observables were extracted from Delay Doppler Maps (DDMs) after taking the receiver antenna gains effects and GNSS-R geometry effects into account. Since the DDM is affected by GPS EffectiveIsotropic Radiated Power (EIRP), we first investigate the sensitivity of observables to the GPS block. Additionally, the observables at high SNRs are more sensitive to wind speed, but the spatial coverage at high signal to noise ratios (SNRs) is lower, while DDMs at low SNRs have the opposite characteristics. To balance the accuracy and spatial coverage, the DDM datasets are divided into two parts: high SNR (>0 dB) and low SNR (>−10 dB and ≤0 dB) to develop wind GMF. Then, the influences of GPS block on wind speed retrieval both at high and low SNR is analyzed. Results show that the block types have impacts on wind GMF and the use of a prior GPS block can contribute to a better wind speed retrieval both at high and low SNR. Compared with ASCAT, the Root Mean Square Error (RMSE) value of wind speed retrieval at high and low SNR are 2.19 m/s and 3.13 m/s, respectively, when all TDS data are processed without distinguishing GPS block types. However, if the TDS data are separately processed and used to develop wind GMF through different blocks, both the accuracy and correlation coefficient can be improved to some extent. Finally, the influence of significant height of the swell (Hs) on SNR observables is analyzed, and it is demonstrated that there is no obvious linear or nonlinear relationship between them.

Characterization and Calibration of Spaceborne GNSS-R Observations Over the Ocean From Different BeiDou Satellite Types

The Global Navigation Satellite System Reflectometry (GNSS-R) technique can measure ocean surface winds and other geophysical parameters from forward scattered GNSS (GPS, BeiDou, Galileo, etc.) signals. However, most early spaceborne missions only captured GPS signals while the study of spaceborne reflectometry using BeiDou signals (BDS-R) is limited. The GNOS-II payload onboard China’s FY-3E satellite has been operationally collecting a large number of BDS-R data since July 10, 2021. BDS is different from GPS in the orbit, signal frequency, chipping rate and Effective Isotropic Radiated Power (EIRP). Furthermore, BDS satellites have different generations and orbits. This paper, for the first time, comprehensively characterizes the spaceborne BDS-R observations over the ocean using the FY-3E GNOS-II data from different BDS satellite types including BDS-2 IGSO, BDS-2 MEO, BDS-3 IGSO and BDS-3 MEO. Their spatial coverage, spatial resolution, effective scattering area, incidence angle, range corrected gain, EIRP and signal-to-noise ratio have been analyzed and compared to those of GPS-R. Spaceborne BDS-R shows a lot of uniquenesses compared to GPS-R. The BDS-R observables are then calibrated separately for each type. An intercalibration is also applied to correct extra calibration errors. After the calibration, BDS-R observables and retrieved winds are consistent between each type and compared to those of GPS-R. Calibrated observables from FY-3E GNOS-II are also evaluated by comparing them to those measured by the Cyclone Global Navigation Satellite System (CYGNSS) mission and a theoretical model. The results of this paper can provide a reference for future BDS-R studies and spaceborne GNSS-R mission design.

A 420-GHz Sub-5-μm Range Resolution TX–RX Phase Imaging System in 40-nm CMOS Technology

This article presents a 420-GHz phase imaging system designed in a 40-nm CMOS technology. It consists of a transmitter (TX), based on a multiplier chain, and a receiver (RX), based on a two-step IQ down-conversion. Those chips share an external, 17.5 GHz, reference to secure frequency synchronization between them. To increase the overall system signal-to-noise ratio (SNR), the TX is modulated with a low-frequency sine-wave signal, while a two-way LO power combining is implemented for the RX first mixer. Those techniques result in a measured TX effective isotropic radiated power (EIRP) of 10 dBm and RX noise figure (NF) of 27 dB, leading to the overall SNR of 52 dB (at a distance of 25 cm and a resolution bandwidth (RBW) of 100 kHz). Furthermore, the measured phase-detection root-mean-square (rms) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\sigma $ </tex-math></inline-formula> precision is equal to 1.7° (on a 400 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\circ $ </tex-math></inline-formula> range, at a distance of 25 cm and processing time of 500 ns), which leads to 3.4- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> range resolution. In addition, the system operation is illustrated in two imaging demonstrations, recognition of the printed text on paper and 3-D imaging. Those demonstrations illustrate the potential of the presented system and terahertz (THz) phase imaging in general.

LEO Satellite Multibeam Coverage Area Division and Beamforming Method

The low-orbit satellite has a large communication angle, resulting in a large difference in path loss at different angles. The existing multibeam coverage area division method cannot meet the coverage requirement of the effective isotropic radiated power (EIRP) in these large-angle areas. Therefore, this letter proposes a method for dividing the beam coverage area from the outside to the inside. Combined with the subarray multibeam forming method, it achieves the optimal coverage of isoflux multiple beams to the ground with unchanged output power of the transmitter, which greatly improves the overall efficiency of existing beamforming methods. At the meantime, a frequency reuse color separation algorithm based on the depth first search is proposed to reduce the mutual interference among nonuniform multiple beams. As an example, 52 beams with 12-color frequency reuse are designed to cover ±55°. The edge EIRP of a single beam is no less than 25.5 dBW and the carrier-to-interference ratio is no less than 16 dB.

빔 스위칭을 이용한 24 GHz 장거리 탐지용 레이다 송신기

This paper proposes a three-dimensional 24 GHz frequency modulated continuous-wave (FMCW) radar transmitter for long-range detection. The proposed transmitter implements seven switched vertical fan beams from 15° to −15° for high effective isotropic radiated power (EIRP) and vertical angle detection. Instead of using lossy electronic switches and large passive beamforming networks, the beamforming transmitter is achieved by directly switching the power amplifier, which drives a sectoral series patch array antenna. The EIRP of each beam is approximately 48.676 dBm, and the size of the transmitter is 27.5 cm × 11 cm.

A 482-GHz 2-D Scalable and Wideband Radiator Array

This letter reports a 2-D scalable coupled harmonic oscillator array achieving coherent spatial power combining at about 500 GHz. This design is implemented using on-chip microstrip lines and microstrip antennas by which the lossy silicon substrate is shielded and, therefore, front side radiation could be obtained. Compared with previously reported scalable array designs, this work not only achieves maximum oscillation at the fundamental frequency, but also decouples the design of oscillator core, radiation element, and coupling structure. Therefore, different parts could be separately optimized to achieve maximum radiated second harmonic power and more design diversity is possible for the antenna part. To demonstrate the design concept, a 2×2 coupled oscillator array is designed and fabricated using 65-nm CMOS process, which achieves a maximum effective isotropic radiated power (EIRP) of 2.6 dBm and radiated power of 162.2 μW (-7.9 dBm) at 482 GHz. It consumes 154-mW dc power and the dc-to-terahertz (THz) efficiency is 0.11%. This design achieves a 6.8% tuning range from 469 to 502 GHz by changing the bias voltages.

Highly Integrated PA-PIFA With a Wide Frequency Tuning Range

This letter presents a highly integrated power amplifier (PA) antenna with the capability of frequency tuning. A planar inverted-F antenna (PIFA) is used to directly match the PA transistor. This mitigates the lossy output matching network in the PA-integrated antenna (PAIA). In order to achieve a wide frequency tuning range, a combination of capacitors is loaded at the PIFA to control the antenna input impedances so that matching can be maintained with frequency tuning. The antenna analysis and design procedure of the tunable PAIA are detailed. For verification, a prototype is designed, fabricated, and measured. The experimental results show that the frequency tuning range of the proposed PAIA covers from 2 to 4 GHz. Over this frequency tuning range, the effective isotropic radiation power and power-added efficiency are higher than 40.5 dBm and 60% at the input power of 26.5 dBm, respectively.

A Phase-Based Ranging Method for Long-Range RFID Positioning With Quantum Tunneling Tags

This work demonstrates the ability to extend the positioning range of low-powered RFID tags to distances usually not achievable with other wireless or conventional RFID technologies. The technique is performed through a Received Signal Phase (RSP)-based method on a 5.8 GHz backscatter tunneling tag, in multipath-rich indoor and outdoor environments, at distances up to 35 meters from the reader. Distance errors as low as 0.1% of the total reader-to-tag distance were observed with average errors of 0.8% and 0.6% for indoor and outdoor environments, respectively. Compared to Received Signal Strength (RSS)-based techniques, the average distance estimation accuracy is improved by a factor of 51 and 38 for indoor and outdoor environments, respectively. Moreover, an Effective Isotropic Radiated Power (EIRP) of only 10.5 dBm and a biasing power for the tunneling tag of only $21.3~\mu \text{W}$ at 80 mV promise a low-power, long-range sub-meter scale positioning technique with a projected maximum range over 1 km.

Uniformly Distributed Near-Field Probing Array for Enhancing the Performance of 5G Millimeter-Wave Beamforming Transmitters

This letter proposes a uniformly distributed near-field (NF) probing array (NFPA) capable of generating feedback signals suitable for monitoring and improving the performance of a 5G millimeter-wave (mm-wave) beamforming transmitter. The proposed NFPA configuration is carefully designed to ensure comparable coupling ratios between the individual RF chain outputs and the closest NF probes, across a wide frequency range. This maximizes the quality of the feedback signal available to perform array calibration and digital predistortion (DPD) when using realistic 5G modulated signals. A 16-element 27-30-GHz beamforming transmitter is designed and serves as the proof-of-concept prototype. Using a four-element NFPA, the 16 RF chains are calibrated using a 400-MHz modulated signal - achieving less than 0.27 dB and 2.8° root-mean-square (RMS) magnitude and phase calibration errors, respectively. Furthermore, a DPD engine trained using the NFPA-based feedback signal improves the over-the-air transmitted signal's adjacent channel power ratio (ACPR) and error vector magnitude (EVM) from 30 dB and 8.8% to 39 dB and 2.5%, respectively. The DPD also allowed for an increase of the effective isotropic radiated power (EIRP) from 27.5 to 33 dBm while staying below the maximum EVM of 3.5%.

Dynamic Calibration of GPS Effective Isotropic Radiated Power for GNSS-Reflectometry Earth Remote Sensing

Global Navigation Satellite System (GNSS) Reflectometry uses reflected GNSS signals for Earth remote sensing applications. Absolute calibration of a Delay Doppler Map (DDM) requires an accurate estimate of the effective isotropic radiated power (EIRP) of the GNSS transmitter, e.g., Global Positioning System (GPS). However, variable transmit power by numerous Block II Follow-on (IIF) and II Replenishment-Modernized (IIR-M) GPS space vehicles has been observed due to their flex power mode. Nonuniformity in the GPS antenna gain patterns further complicates EIRP estimation. A dynamic calibration approach is developed to address GPS EIRP variability. It uses measurements by the direct received GPS signal to estimate GPS EIRP in the specular reflected direction and then incorporates it into the calibration of normalized bistatic radar cross section (NBRCS). Error analyses using Monte Carlo simulations and a root sum of squares (RSS) approach show that the resulting error in NBRCS is about 0.32 dB. Dynamic EIRP calibration instantaneously detects and corrects for power fluctuations in the GPS transmitters and significantly reduces errors due to GPS antenna gain azimuthal asymmetry. It allows observations with the most variable Block IIF transmitters (approximately 37% of the GPS constellation) to be included in the standard data products and further improves the calibration quality of NBRCS and geophysical data products.

A 256-Element Ku-Band Polarization Agile SATCOM Transmit Phased Array With Wide-Scan Angles, Low Cross Polarization, Deep Nulls, and 36.5-dBW EIRP per Polarization

This article presents an ultralow-profile and lightweight Ku-band transmit phased array with 256 dual-polarized antenna elements for SATCOM on-the-move (SOTM) terminals. The antennas are placed in a square grid with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> /2 spacing at 14 GHz. At normal incidence, the phased array results in a measured effective isotropic radiated power (EIRP) of 64.5 and 66.5 dBm at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$P_{\mathrm {1~dB}}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$P_{\mathrm {sat}}$ </tex-math></inline-formula> , respectively, per polarization. The measured patterns, in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> - and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$H$ </tex-math></inline-formula> -planes, show almost ideal patterns with a wide scanning range of ±60°, a 3-dB instantaneous bandwidth of 13.0–14.6 GHz, and a cross-polarization isolation of 27 dB up to ±45° and 23 dB at ±60° scan angles. In the circular polarization mode, the measured axial ratio (AR) is <1.1 dB at 14–14.5 GHz. The phased array is also capable of synthesizing deep nulls (−30 to −40 dB) over a wide range of angles, thereby reducing unintended radiation to geostationary orbit (GEO) satellites. Transmit noise analysis is presented and shows that the array signal-to-noise ratio (SNR) is dominated by the block upconverter (BUC) and not by the beamformers. An error vector magnitude (EVM) of 2.8%–3.5% was achieved over a wide scan range for QPSK, 8-PSK, and 16-PSK waveforms with 100-MHz bandwidth. The array near-ideal performance, compact size, low profile with 3.5-mm thickness, and ultralightweight of 212 g make it ideal for affordable Ku-band SATCOM terminals.

A 148-GHz Radiator Using a Coupled Loop Oscillator With a Quad-Feed Antenna in 22-nm FD-SOI

This article presents a 148-GHz coupled loop fundamental oscillator with a quad-feed octagonal slot antenna. The proposed loop configuration with a multi-feed antenna leads to each oscillator experiencing multiple injected signals. An analysis is performed to explain the dynamics of the coupled loop oscillator in the presence of multiple signal-injection paths. It is shown that the proposed oscillator configuration will only operate with - π/2 phase between the adjacent oscillators. This phase difference is necessary for the quad-feed antenna to combine and radiate the output power from the four single-ended oscillators in the loop. The output from each oscillator is ac coupled to the following oscillator stage using a phase compensating capacitor, whose value is selected to enhance the oscillation frequency of the coupled loop. The use of buffer stages is avoided in favor of a passive power feed network for extraction of the output power from each oscillator. The proposed oscillator is fabricated in a 22-nm FDSOI process and has a 0.5-mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> chip area. The measured peak effective isotropic radiated power (EIRP) of the oscillator is 9.7 dBm with a corresponding dc-EIRP efficiency of 34.3% when operating from a 0.8-V supply. To the authors' knowledge, this dc-EIRP efficiency is the highest among reported oscillators to date operating between 100 and 200 GHz.

Compact shorted C‐shaped patch antenna for ultrahigh frequency radio frequency identification tags mounted on a metallic plate

This paper describes an ultrahigh frequency (UHF) tag antenna mounted on a metallic plate for radio frequency identification (RFID). The impedance of the proposed antenna can be tuned using various methods. The compact patch antenna consists of a C-shaped resonator and a ground plane connected to a small shorting wall and is connected to a feeding loop in the middle of the C-shaped resonator. Etching a couple of slits close to the shorting wall and a slot in the center of the C-shaped resonator provided a flexible method for adjustment to match the conjugate impedance with the UCODE 8/8 m chip (13 − j191 Ω at 915 MHz). The optimal design with an overall size of 30 × 30 × 3 mm3 (0.092 λ0 × 0.092 λ0 × 0.0092 λ0) yielded a high power transmission coefficient of 91% and reading range of 6.4 m for the effective isotropic radiated power (EIRP) of 4.0 W when the tag antenna was mounted on a 220 × 220 mm2 metal plate. The proposed antenna was designed at standard frequency bands of the Federal Communications Commission (FCC, 902-928 MHz) for North America and Taiwan. Antenna fabrication and testing were performed, which revealed that the measured data were in good agreement with the simulation results.

항공기탑재 레이다용 X-대역 Low-Profile 능동위상배열 안테나 설계 및 제작

The results of the fabrication of active electronically scanned array (AESA) antennas with low-profile, low-weight, wide-scan, and thermal stability characteristics for aircraft-mounted radar are described. To reduce the size and weight of the antenna, a transmit–receive block is constructed in a quasi-tile structure in which the radio-frequency circuit-related transmit–receive module is a brick type, which is a flat structure, and the control board is a tile type, which is a stacked structure, to reduce the depth of the front of the antenna. In addition, the depth of the rear part of the antenna was reduced by manufacturing power and plate-shaped control-related modules at the rear of the antenna. The reduced antenna depth maximizes the effective isotropic radiated power (EIRP) and gain to noise temperature (G/T) by enlarging the antenna aperture. The manufactured antenna can scan a wide angle of ±70°. The cooling efficiency is improved by using a dual cooling structure that allows the cooling water to pass through the front cooling plate and then through the rear cooling plate. The EIRP of the manufactured AESA antenna is 104.04 dBmi, and G/T is 7.46 dB/K in Taylor weighting.

RF-Powered Low-Energy Sensor Nodes for Predictive Maintenance in Electromagnetically Harsh Industrial Environments.

This work describes the design, implementation, and validation of a wireless sensor network for predictive maintenance and remote monitoring in metal-rich, electromagnetically harsh environments. Energy is provided wirelessly at 2.45 GHz employing a system of three co-located active antennas designed with a conformal shape such that it can power, on-demand, sensor nodes located in non-line-of-sight (NLOS) and difficult-to-reach positions. This allows for eliminating the periodic battery replacement of the customized sensor nodes, which are designed to be compact, low-power, and robust. A measurement campaign has been conducted in a real scenario, i.e., the engine compartment of a car, assuming the exploitation of the system in the automotive field. Our work demonstrates that a one radio-frequency (RF) source (illuminator) with a maximum effective isotropic radiated power (EIRP) of 27 dBm is capable of transferring the energy of 4.8 mJ required to fully charge the sensor node in less than 170 s, in the worst case of 112-cm distance between illuminator and node (NLOS). We also show how, in the worst case, the transferred power allows the node to operate every 60 s, where operation includes sampling accelerometer data for 1 s, extracting statistical information, transmitting a 20-byte payload, and receiving a 3-byte acknowledgment using the extremely robust Long Range (LoRa) communication technology. The energy requirement for an active cycle is between 1.45 and 1.65 mJ, while sleep mode current consumption is less than 150 nA, allowing for achieving the targeted battery-free operation with duty cycles as high as 1.7%.

A CMOS Dual-Polarized Phased-Array Beamformer Utilizing Cross-Polarization Leakage Cancellation for 5G MIMO Systems

This article introduces a power-efficient and low-cost CMOS 28-GHz phased-array beamformer supporting fifth-generation (5G) dual-polarized multiple-in-multiple-out (MIMO) (DP-MIMO) operation. To improve the cross-polarization (cross-pol.) isolation degraded by the antennas and propagation, a power-efficient analog-assisted cross-pol. leakage cancellation technique is implemented. After the high-accuracy cancellation, more than 41.3-dB cross-pol. isolation is maintained along with the transmitter array to the receiver array. The element-beamformer in this work adopts the compact neutralized bi-directional architecture featuring a minimized manufacturing cost. The proposed beamformer achieves 22% per path TX-mode efficiency and a 4.9-dB RX-mode noise figure. The required on-chip area for the beamformer is only 0.48 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . In over-the-air measurement, a 64-element dual-polarized phased-array module achieves 52.2-dBm saturated effective isotropic radiated power (EIRP). The 5G standard-compliant OFDMA-mode modulated signals of up to 256-QAM could be supported by the 64-element modules. With the help of the cross-pol. leakage cancellation technique, the proposed array module realizes improved DP-MIMO EVMs even under severe polarization coupling and rotation conditions. The measured DP-MIMO EVMs are 3.4% in both 64-QAM and 256-QAM. The consumed power per beamformer path is 186 mW in the TX mode and 88 mW in the RX mode.