This research proposes a system board of integrated antenna scheme of near-field communication (NFC) and dual band ultra-high frequency (UHF, 920–925 MHz)/2.45 GHz radio frequency identification (RFID) reader antennas for Internet of Things (IoT) applications. The integrated antenna scheme is capable of simultaneous execution of NFC and UHF RFID functions whereby the NFC and UHF RFID modules, which are serially connected to a microcontroller with Wi-Fi module (NodeMCU), read the universal identification (UID) of NFC and UHF RFID tags. The data are then forwarded to a cloud server via Internet of Things (IoT) and are viewable on smartphones using Blynk mobile application via IoT. To realize the optimal antenna design, simulations were carried out using CST Studio Suite. Prototype antennas were subsequently fabricated and integrated into the system board for IoT-linked near- and far-field communication. The simulation and measured results are in good agreement. The NFC reader antenna resonates at 13.56 MHz, and the dual band UHF/2.45 GHz RFID reader antenna achieves the 920–925 MHz and microwave (MW) bands with high isolation. The novelty of the proposed integrated NFC and UHF RFID antenna scheme lies in the use of cloud technology to store real-time and archival data, in place of traditional servers. The integrated antenna scheme could achieve the NFC, UHF, and MW frequency bands, rendering it ideal for IoT applications.

/pdf/iot-linked-integrated-nfc-and-dual-band-uhf-2-45-ghz-rfid-2gzuy7a33c.pdf

IoT-Linked Integrated NFC and Dual Band UHF/2.45 GHz RFID Reader Antenna Scheme

In this letter, we present a new approach of using time-modulated phased arrays to synthesize multicarrier directional modulation (DM) symbols for physical-layer security In particular, the modulated waveform synthesis is achieved with the careful design of the switching time sequences, instead of in digital baseband; thus, reducing the peak-to-average power ratio of signals going through the radio frequency (RF) chain, and only a single RF chain is required here The operation principle and synthesis approach are elaborated and demonstrated In addition, the efficacy of the proposed DM approach is validated via the bit-error-rate (BER) metric

Multicarrier Directional Modulation Symbol Synthesis Using Time-Modulated Phased Arrays

A novel beam scanning method utilizing the carrier frequency component for time-modulated array (TMA) is proposed and a significant algorithm based on the non-uniform period modulation is implemented to suppress the maximum sideband radiation (SR) level. The signal in each channel is modulated by a pair of high-speed radio-frequency (RF) switches and totally three or four delay lines with different phases. In each modulation period, three selected delay lines are connected successively with proper pulse durations to keep the switches in ON states constantly and ensure the maximum efficiency in the feeding network. Additionally, in order to suppress the relatively higher SR generated by both switches and delay lines, each channel of the TMA system has a different modulation period, which will separate the harmonic components of different elements on the frequency axis. A desired relatively low maximum SR level without complicated optimization is obtained compared with uniform period modulation and optimization algorithms. Several numeric simulations are brought out to examine the performance of the proposed methods, and the results for comparison to existing methods are also provided. A group of experiments have been done to verify its effectiveness.

Low Sideband Radiation Beam Scanning at Carrier Frequency for Time-Modulated Array by Non-Uniform Period Modulation

Multibeam steered pattern synthesis in time‐modulated antenna array with controlled harmonic radiation

\n An efficient analysis of time-modulated array (TMA) toward realizing less-attenuating radiation patterns with simultaneously suppressed sidelobe and sidebands is presented in this paper. In this framework, an optimal outer element-controlled time sequence is derived. The proposed time scheme, along with optimized array excitations, is profitably applied for the desired solution. TMAs are considered unconventional alternatives to the phased arrays. The desired array radiation features can be attained by periodically enabling and disabling the array elements through high-speed switches. Despite the advantages of architectural simplicity and real-time reconfigurability of periodic time sequences, time-domain antenna arrays inherently generate unavoidable sideband radiations (SRs). The undesired SRs obtained at multiple harmonics around the carrier frequency of the array resembles power loss in unintended directions. This paper aims to minimize the SRs as well as the sidelobe level (SLL) for an efficient analysis of time-modulated linear array (TMLA) with high-directive radiation patterns. The starting instants and the period of on-times are optimized to generate a unique shifted time scheme for the edge elements of the TMLA to reduce the sideband levels (SBLs). The array excitations and the uniform spacing between the elements are also optimized together with the shifted time scheme for the coveted solution. Other methods of suppressing SLLs and SBLs with shifted pulse schemes and sub-sectioned pulse schemes are also presented for a fair comparison. Modified versions of the particle swarm optimization algorithm (PSO) are applied for the desired solutions. The optimal results attained by wavelet mutation-based novel PSO is compared with the conventional PSO and the modified novel PSO-based results. The representative results are reported, and the superior performance abilities of the proposed method compared to other published studies are assessed.

Time-modulated linear array synthesis with optimal time schemes for the simultaneous suppression of sidelobe and sidebands

In this paper, a novel module named time-modulated amplitude-phase weighting with multiple branches (TMAPW-MB) is proposed to realize harmonic beamforming. The harmonic beamforming is then explored to eliminate the conventional digital phase shifters and digital attenuators in antenna arrays. The input and output of general linear frequency modulation (LFM) are investigated in a four-branch TMAPW-MB module. The analysis and numerical results exhibit the attractive capability in the suppression of unwanted harmonic component in radio-frequency (RF) channels. Then, the proposed TMAPW-MB modules are employed in an $X$ -band $1 \times 16$ Vivaldi antenna array for amplitude-phase weighting and, therefore, beamforming. The numerical results show that radiation patterns with −25.0 dB sideband levels (SBLs), −20.0 dB sidelobe levels (SLLs), and ±50° beam scanning range could be realized through the proposed TMAPW-MB module. Meanwhile, due to the removed quantization errors in traditional digital phase shifters and digital attenuators, the proposed module ensures real-time, continuous beam scanning, and precisely controlled SLL and SBL in antenna arrays.

Harmonic Beamforming in Antenna Array With Time-Modulated Amplitude-Phase Weighting Technique

In this letter, we propose a wideband, low-profile phased array with vertically polarized end-fire radiation patterns. The array consists of four identical log-periodic top-hat monopole antennas (LPTMAs) and could be completely embedded within a shallow cavity for sight invisible integrated installation on metallic platforms. Simulation results show that the proposed array operates over a wide frequency band of 1.0–3.0 GHz for active voltage standing wave ratio <2.0. It also possesses end-fire radiation patterns with ±45° beam scanning capability in the horizontal plane. Prototypes of the proposed LPTMA and a uniformly spaced linear array (1 × 4) are fabricated and validated in experiments. Measured results are in a good agreement with the simulation results. The measured results demonstrate that the proposed end-fire scanning array is attractive for applications that require wideband beam scanning, excellent aerodynamic, and stealth performances.

A Wideband, Low-Profile Log-Periodic Monopole Array With End-Fire Scanning Beams

Amplitude-phase weighting modelling and analysis are indispensable for the performance evaluation of a practical, nonideal time-modulated antenna array (TMA). This paper investigates the effective performance evaluation of a crucial component in TMAs, named the time-modulated amplitude-phase weighting (TMAPW) module, while its performance is analysed through a single radio frequency (RF) channel and radiation patterns. A mathematical model is developed for amplitude-phase evaluation with nonideal time modulation sequence (TMS). A comparative measurement methodology is proposed to directly measure the attenuated amplitude and shifted phase at harmonic frequencies. Experimental validation for the developed mathematical model is carried out through an X-band prototype of the TMAPW module. Harmonic beamforming is then analysed in a 32-element nonideal TMA. Based on the developed model, the nonideal TMS can accurately evaluate the attenuated amplitude, shifted phase, and power spectrum leakage effect of the fabricated TMAPW module. Moreover, the sidelobe level (SLL) errors in radiation patterns are reduced with the proposed nonideal TMS. Consequently, the developed mathematical model and the measurement methodology will benefit the accurate performance evaluation of nonideal TMAs.

Design and analysis of an amplitude-phase weighting module for harmonic beamforming in time-modulated antenna arrays

A novel printed center-fed dual-log-periodic array antenna is proposed for ultrahigh frequency (UHF) radio frequency identification (RFID) applications. The proposed antenna is composed of two reversed wideband printed log-periodic dipole array antennas. Two closely spaced oppositely directed currents are thus introduced to achieve intensive and uniform magnetic fields in the near-field zone. A prototype antenna is fabricated and measured in practical application environment. The measurement results agree well with the simulations, and demonstrate that the proposed antenna is suitable to be implemented in RFID systems. The operated frequency band of the antenna is 824–953 MHz (14.5%), covering the UHF band in China, the Federal Communications Commission band, and the European Telecommunications Standards Institute band. With the proposed printed dual-log-periodic array antenna, measurement results also show that the RFID system delivers a 100% guaranteed reading rate within 2.0 cm and a maximum reading range of 19.0 cm.

A Novel Printed Dual-Log-Periodic Array Antenna for UHF Near-Field RFID Applications

In this paper, the single-pole single throw (SPST) radio frequency (RF) switches are investigated for pattern synthesis of a practical X-band 16-element Vivaldi linear array. With the periodicity of the SPST RF switches, the conventional digital phase shifters and digital attenuators are removed. The effective multiobjective evolutionary algorithm based on objective decomposition (MOEA/D) is employed for pattern synthesis. The patterns with -20.0 dB sidelobe level (SLL) are obtained at the fundamental, positive and negative first harmonics. Meanwhile, the scanning beams are also achieved.

Haotian Li

Papers

Harmonic Beamforming in Antenna Array With Time-Modulated Amplitude-Phase Weighting Technique

A Wideband, Low-Profile Log-Periodic Monopole Array With End-Fire Scanning Beams

Design and analysis of an amplitude-phase weighting module for harmonic beamforming in time-modulated antenna arrays

A Novel Printed Dual-Log-Periodic Array Antenna for UHF Near-Field RFID Applications

Pattern Synthesis of a Time-modulated Vivaldi Linear Array with MOEA/D Algorithm