“Unconventionally Shaped” Antenna Design for UHF RFID Tags

Abstract

UHF RFID tags need to be attached or embedded into various objects. Unlike traditional free-standing antennas, UHF antenna shapes and form factors may vary significantly. There have been no systematic methods that facilitate the design practice of antenna with unconventional shapes. In this paper, using the geometries of 26 English letters (in capital) as examples, we explore the general methodology of shape-specific antenna design. More specifically, we show that 26 letter geometries can be categorized into 9 groups, and the antennas in each group can be divided and conquered into standard baseline geometries. Through prototypes and measurements, we demonstrate that each letter-shaped antenna, although exhibiting different gains and radiations, can achieve satisfactory performance, as compared to standard UHF dipole antennas. Specifically, letters “M” and “J” achieve the longest reading range of more than 20 meters with a good radiation pattern, which is comparable or even better than many commercial UHF RFID tags.

Design of a Flexible T-Matched Feed UHF RFID Tag Antenna

“…The equivalent circuit tag antenna with T-match feed line is depicted in Figure 2 [17]. The input impedance of the proposed antenna in Figure 1, is given as [18] 𝑍 𝑎 = 𝑅 𝑎 + 𝑗𝑋 𝑎 = 𝑍 𝑡 + 𝑍 𝑐𝑡𝑝 + (2𝜋𝑓𝑀) 2 𝑍 𝑚 (1) where Zt is the T-match feeder impedance, Zctp is the impedance of the capacitive tip loading, Zm is the meandered line impedance and M is the inductive mutual coupling between the T-match feeder and radiating body including meandered line and capacitive tip loading. The transfer power coefficient,  is given by [19] :…”

Flexible, Fully Printable, and Inexpensive Paper-Based Chipless Arabic Alphabet-Based RFID Tags

“…The examples of later category are Latin alphabets [1,6,9,[24][25][26], Arabic letters [4,12], and peyote symbols [1,2]. The study of [27] reflects that Latin letter tags could also be used as dipole antennas. The usage of metallic letters for the RFID applications offers advantages of visual identification for the line of sight and radio frequency recognition for non-line-of-sight configurations [1,2,9].…”