In this paper, an overview of antenna design for passive radio frequency identification (RFID) tags is presented. We discuss various requirements of such designs, outline a generic design process including range measurement techniques and concentrate on one practical application: RFID tag for box tracking in warehouses. A loaded meander antenna design for this application is described and its various practical aspects such as sensitivity to fabrication process and box content are analyzed. Modeling and simulation results are also presented which are in good agreement with measurement data.

Antenna design for UHF RFID tags: a review and a practical application

RFID research: An academic literature review (1995–2005) and future research directions

This paper presents the use of pin diodes to reconfigure the impedance match and modify the radiation pattern of an annular slot antenna (ASA). The planar antenna is fabricated on one side of a Duroid substrate and the microstrip feeding line with the matching network is fabricated on the opposite side of the board. The central frequency is 5.8 GHz and, by reconfiguring the matching circuit, the antenna was also designed to operate at 5.2 and 6.4 GHz. Pin diodes are also used to short the ASA in preselected positions along the circumference, thereby changing the direction of the null in the plane defined by the circular slot changes. As a proof of concept, two pin diodes are placed 45/spl deg/ on both sides of the feeding line along the ASA and the direction of the null is shown to align with the direction defined by the circular slot center and the diode. Consequently, a design that is reconfigurable in both frequency and radiation pattern is accomplished. Return loss and radiation pattern measurements and simulations are presented, which are in very good agreement.

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Pattern and frequency reconfigurable annular slot antenna using PIN diodes

This paper has presented a comprehensive overview of on-chip antennas, which remain the last bottleneck for achieving true SoC RF solutions. CMOS remains the mainstream IC technology choice but is not well suited for on-chip antennas, requiring the use of innovative design techniques to overcome its shortcomings. Codesign of circuits and antennas provide leverage to the designer to achieve optimum performance. The layout of on-chip antennas is dictated by foundry specific rules whereas characterization of on-chip antennas requires special text fixtures. For future highly integrated SoC solutions, foundries will have to provide special layers for efficient on-chip antenna implementations, as they currently do for on-chip inductors. In many of the emerging applications such as THz communication, implantable systems and energy harvesting, on-chip antennas have shown immense potential and are likely to play a major role in shaping up future communication systems.

The last barrier: on-chip antennas

The present invention provides a high-speed electrical interconnection system designed to overcome the drawbacks of conventional interconnection systems. That is, the present invention provides an electrical connector capable of handling high-speed signals effectively.

High-speed electrical connector

A coplanar waveguide (CPW)-fed capacitive folded-slot antenna is proposed for the radio frequency identification (RFID) application at 5.8 GHz. The antenna is fabricated on a 30×30 mm substrate. The measured bandwidth and antenna gain are 7.5% and 4.2 dBi, respectively. Radiation patterns are almost omnidirectional in the H-plane. These properties and the compact and uniplanar structure make the antennas suitable for use as RFID tags.

CPW-fed folded-slot antenna for 5.8 GHz RFID tags

A novel design of a differential-mode (DM) wideband bandpass filter (BPF) with enhanced common-mode (CM) suppression using a slotline resonator is presented The BPF consists of two pairs of parallel microstrip transmission lines, a pair of transverse microstrip sections connected to the transmission lines, and a longitudinal slotline resonator placed in the ground plane With proper placement of the slotline resonator, the mode coupling between the slotline mode and the (DM) signals can be maximized, while that between the slotline mode and the CM signals can be minimized It is found that throughout the (DM) passband, the insertion loss of the CM signals is higher than 475 dB, the fractional bandwidth defined by the 10 dB return loss for the (DM) signals is about 105%, and the insertion loss for the (DM) signals ranges from 122 to 582 dB over the fractional bandwidth Good agreement between simulated and measured results is obtained

A Differential-Mode Wideband Bandpass Filter With Enhanced Common-Mode Suppression Using Slotline Resonator

A modified slot dipole antenna fed by a coplanar waveguide for dual-frequency operation is presented. This antenna is formed by placing an additional slot dipole parallel to the coplanar waveguide-fed inductive slot dipole antenna, and inserting between them a pair of slot apertures shorter than the two slot dipoles. By varying the lengths of the protruded portions of these two slot dipoles, two operating frequency bands can be obtained. The tuning range of the frequency ratio of the two resonant frequencies is between 1.3 and 2.5. The proposed antenna possesses similar and well-behaved radiation performances in the two operating bands.

Dual-Band Slot Dipole Antenna Fed by a Coplanar Waveguide

A coplanar waveguide-fed uniplanar log-periodic slot antenna suitable for use in the ultra-wideband radio systems is presented. The in-band impedances and radiation performances are quite stable and satisfactory. A rejected narrow frequency band is further obtained within the wide bandwidth by inserting a pair of metallic stubs into two vertical slots of the proposed antenna. Experimental results reveal that the stub pair provides significant attenuation in the desired notched band but has little effect on the antenna operation outside of the notch. By means of a normalized antenna transfer function, the time-domain characteristics of the proposed antennas are also investigated. The transient responses show that the designs with and without the notched band are both acceptable for the pulsed systems

Uniplanar Log-Periodic Slot Antenna Fed by a CPW for UWB Applications

An isosceles triangular slot antenna is proposed for broadband dual polarization applications. The proposed design has a very simple antenna structure and a wide impedance bandwidth ( ~ 19.7% for |S11| and |S22| les -10 dB) which can cover the 5 ~ 6 GHz frequency band for Wireless Local Area Network applications. Good isolation between the two input ports |S21| and low cross-polarization radiation level (<-15 dB) are achieved, and the antenna gains radiated from the two diversity ports are almost equal and stable over the entire operating band. These features make the proposed antenna very attractive in broadband dual polarization applications.

Powen Hsu

Papers

CPW-fed folded-slot antenna for 5.8 GHz RFID tags

A Differential-Mode Wideband Bandpass Filter With Enhanced Common-Mode Suppression Using Slotline Resonator

Dual-Band Slot Dipole Antenna Fed by a Coplanar Waveguide

Uniplanar Log-Periodic Slot Antenna Fed by a CPW for UWB Applications

Isosceles Triangular Slot Antenna for Broadband Dual Polarization Applications