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Loop-Coupled Small Antenna With Enhanced Bandwidth for On-Metal UHF RFID Tag Design

A small antenna with a dimension of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$36\times 39\times1.5$ </tex-math></inline-formula> mm ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.109\lambda \times 0.118\lambda \times 0.0045\lambda $ </tex-math></inline-formula> ) is proposed for wideband metal-mountable applications. An excitation loop is designed within the antenna structure for achieving good energy coupling from the loop to the outer patch. With the introduction of a narrow stub, connecting the top and bottom conductors, the 3 dB impedance bandwidth of the proposed tag can be enhanced from 16 to 50 MHz, without modifying other design parameters. The bandwidth and the impedance matching between the antenna and the microchip can be tuned by varying the stub width. The gap separation between the top patches and the L-slot on the patch can also be adjusted for bandwidth optimization. The tag is readable from at least 6 m within 896–917 MHz, regardless of the metal plate dimension (12–24 cm). The tag is also readable from at a minimum of 4 m within a wide frequency range of 887–927 MHz, covering the entire US UHF radio frequency identification (RFID) band when attached to different sizes of metallic items.

Periodic strip loaded reconfigurable half‐mode substrate integrated waveguide‐based leaky wave antennas

In this Letter, a reconfigurable half-mode substrate integrated waveguide (HMSIW)-based leaky-wave antenna (LWA) configuration with its edge loaded with the periodic strips is investigated. A good impedance matching is obtained using the loaded configuration. A microstrip line with a tapered-line transition is used to feed the proposed antenna structure. Beam scanning of 24°–66° in the frequency band 9.07–11.04 GHz is achieved with the maximum gain of 14.58 dBi at the frequency 10.07 GHz with a corresponding beam direction of 48°. Thereafter, the edge of the strips is loaded in the middle with variable capacitors connected through narrow stubs to scan the beam at a fixed frequency. The variation in reflection and transmission coefficients, beam angle and antenna gain with variation in the capacitor value for the loaded configuration is investigated.

Compact dual‐band rectenna for RF energy harvest based on a tree‐like antenna

A novel compact dual-band rectenna is presented for efficient radio frequency (RF) energy harvest at 2.45 GHz WiFi and 3.5 GHz WiMAX bands. The proposed rectenna is composed of an optimised tree-like receiving antenna and a compact rectifier based on a two-branch matching network. The tree-like antenna is found to feature a dual-band characteristic, high radiation efficiency, and improved reflection coefficient with the newly designed slotted ground plane. By introducing the matching network which consists of two different radial branches, the proposed antenna is well matched with the rectifying circuit and most part of the received power could be delivered. Besides, in order to eliminate the coupling effects, reduce the energy loss and minimise the overall dimension of the rectenna, three narrow stubs on the ground plane of the antenna are designed to perform as the ground of the rectifier. The results have demonstrated the designed rectenna exhibits relatively stable conversion efficiency for the load value varying from 0.9 to 20 kΩ under low input power and the maximum conversion efficiency is observed to be 60% at 2.45 GHz and 53% at 3.5 GHz under the input power of 0 dBm.

BROADBAND SUBSTRATE TO SUBSTRATE INTERCONNECTION

A broadband substrate to substrate microwave circuit interconnection is proposed using bond wires and defected ground structure (DGS). The proposed square-shaped DGS etched under compensated microstrip open stubs not only expands its operating bandwidth, but also increases the characteristic impedance of microstrip line without narrowing its width, which breaks the PCB fabrication limitation of narrow stubs. The proposed structure can make the impedance of the microstrip line much larger than that without DGS. A 250 Ω characteristic impedance is easily achieved using 0.6 mm microstrip line with the proposed DGS. Measured S21 and S11 of the proposed interconnection are better than −0. 3a nd−15 dB from DC to 38 GHz, respectively. A bandwidth increment of more than 1200% is achieved compared with the conventional one.

Compact size planar folded pifa design for mobile handset

A printed compact size folded inverted-F antenna with simple configuration for mobile handset operating within the global system for mobile communication/personal communication system/digital communication system bands is initially proposed.To additionally cover the wireless local-area network frequency spectrum at 2.4 GHz, a narrow stub is protruded from the printed shorting wall. The excitation of these operating bands with desirable bandwidth is achieved by feeding a 50-Ω microstrip line to the folded radiating element through a via hole. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1045–1050, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25919