Antenna & RF/Microwave System

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Near-field switched loop antenna array with circular DGS for precise positioning systems 11

A near-field switched loop antenna array with a circular defected ground structure for precise positioning systems is presented. By switching the loop array, the positions of the densely placed small-sized radio frequency identification tags can be identified. The characteristics of the proposed array are verified by the comparisons to the simulated results and experimental measurements.

[System Specification]

Frequency band: 840~950MHz

Antenna size: 80…

Rotated stacked Yagi antenna with circular polarization for IoT application 10

 This letter proposes a rotated stacked Yagi antenna with high directivity and circular polarization. The proposed antenna consists of three elements with a rotation angle and different lengths: a director, a reflector, and a driven element connected to the coaxial feeder. Each stacked element with different lengths is equally rotated at an angle of 60° with respect to the lower element so that the dipole array antenna forms a high directive circular polarization.


A Compact module-integrated wireless power transfer system with a square metal plate 9

 Proposed module integrated wireless power transfer antenna with a metal plate inside the loop improves transmission efficiency by reducing the change of mutual inductance caused by the change of distance between two antennas. The antenna was designed and implemented on a 1 mm FR-4 substrate.

[System specification]

Operating Frequency : 6.78 MHz

Transmission Coefficient : -0.72 dB (Max. at 50 mm), -6.34 dB (Min. at 1 mm)

Physical Size : 110 ×…

Electric-field-coupled contactless ID sensor for cm-level high-precision positioning item-level tagging systems 8

 To detect multiple identifications (IDs) for cm-level high-precision positioning item-level tagging (ILT) systems in near-field ultra-high frequency RFID applications, an electric-field-coupled multiple ID sensor is presented. The proposed ID sensor consists of four circular electric coupling parts, an impedance-matching network, and an SP4T switch for position control. By switching the electric-field coupled sensing parts, cm-level position detection of densely aggregated RFID tags for…

A Grid-Shaped Microstrip Traveling Wave Antenna With Selective Differential Feeding Networks for CM-Level Position Detection Systems 7

 A near-field ultrahigh-frequency radio frequency identification (RFID) system, which has cm-level 2-D positioning precision, is proposed. The system consists of a grid-shaped microstrip traveling wave antenna (TWA) and four-port switched differential feeding networks. To selectively form tag-read sections, opposite directional currents (ODCs) are used. 

[System Specification]

Frequency band: 830~950MHz Antenna size: 110×110×1.2 mm Read r…

A Smart Blood Bag Management System Using a Load-Integrated U-Shaped Near-Field RFID Antenna Array 6

 For improving transfusion safety, a smart blood bag management system using a load-integrated U-shaped nearfield antenna (LUNA) array is proposed. The system consists of four LUNAs for ID sensing with blood information and a switching circuit for the sensing of blood bag localization. The proposed system can be used to prevent the mishandling of blood transfusions and to manage blood bags remotely and effectively.

[System Specification] 

Freq. band…

Open-loop Self-Adaptive WPT System for Spatial Freedom 5

 We propose a highly efficient wireless power transfer system with automatic impedance tuning control for practical applications with variable operating distances. Under misalignment between the transmitting and receiving antenna or any operating distance, the proposed distance-adaptive WPT system achieves an improved PTE of maximum 160% by minimizing the reflection coefficient in the transmitting system. It can be useful in wireless charging without the response of the portable receivin…

​Multi-beam antenna system for hemispheric coverage 4

For multi-beam control and compact implementation, the proposed eight-port feeding network consists of an integrated beam-control block with a two-stage RF switch block, 12 quadrature hybrid couplers, and 12 90° phase shifters, and was designed and fabricated on a circular three-layer 1.2 mm FR-4 substrate. The diameter of the fabricated network is ~0.47 λ 0 at 915 MHz.

[Antenna Specification]

​Frequency band : 902-928 MHz

Maximum insertion loss : 4.…

Smart UAV for wireless item management 3

 For wireless item management using a smart UAV, the proposed system consists of UHF RFID reader and antenna, ZigBee for wireless communications, and an UAV. We can detect and manage the items remotely and effectively. This movie shows the proposed smart UAV prototype and  describes the item sensing, and monitoring.

[System Specification]

Item sensing distance : up to 10 m
Wireless communications distance : up to hundreds of meters


900MHz Quadruple-Polarized Reconfigurable Antenna 2

 A quadruple-polarization reconfigurable feeding network for an unmanned aerial vehicle (UAV) RF sensing antenna operating at 915 MHz is presented. It consists of one single-pole four-throw (SP4T) switch, one 90◦ hybrid coupler, two 180◦ hybrid couplers, and two single-pole double-throw (SPDT) switches. By controlling the SP4T and SPDT switches, quadruple polarizations with two linear polarizations (vertical and horizontal) and two circular polarizations (right-hand and left-hand) …

A Printed Fan-shaped Meandered Dipole Antenna 1

​ This letter presents a printed fan-shaped meandered dipole antenna with mutual-coupled dual resonance for enhancing impedance bandwidth in a compact antenna size. The proposed antenna consists of a printed dipole antenna mutually coupled to an antenna parasitic element of a different size for dual resonance and microstrip feeding. 

[Antenna Specification] 

Freq. band : 920 MHz

Impedance BW : 12%

Peak gain : 3.2 dBi

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