The kapton polyimide material is considered to design conformal antenna with spiral square for radio frequency identification (RFID) and wireless local area network (WLAN) applications. In this chapter, the analysis and investigation has been carried out with spiral square techniques using coplanar waveguide (CPW) feed. The proposed antenna operates at 5.8 GHz with impedance bandwidth of 170 MHz (5.73 - 5.9 GHz) with return loss -25.6 dB and gain is 2.4 dBi. The proposed antenna has considered with different bending angles for investigating the conformal characteristics due to flexibility of the material. These results are presented for omni-directional radiation patterns.
TopIntroduction
Rapid growth in wireless communications makes RFID and WLAN technology more popular. RFID is an emerging technology and many service oriented, manufacturing industries, logistics, material flow systems and bio-medical systems use to identify and provide information about goods, products, animals and people (Finkenzeller, Wiley & Sons, 2010). Operating frequency is the most important criterion for RFID systems, federal communication commission (FCC) has allocated 5.8 GHz band for RFID, In bio-medical RFID is used for patient identification (Santiago, Costa, & Fernandes, 2013), (Wang et al., 2005). There are so many RFID systems commercially available with S-band operating frequencies, and an active research is going on for the next higher frequency of RFID systems (Kossel, Kung, Benedickter, & B¨achtold, 1999).
RFID antenna design becomes more complicated and critical for microwave frequency region (Tseng, Huang, & Hsu, 2006). So far, several RFID systems have been proposed, and a capacitive coupled CPW-fed folded-slot structure (Chen & Hsu, 2004) is proposed with single band frequency to obtain miniaturization. Multipurpose novel CPW-fed folded slot monopole antenna (Li et al., 2014) is proposed for RFID/WLAN applications, here the antenna is designed with U, F, L-shape slots to get additional resonances. In (Liu & Hu, 2005) a miniature folded slot CPW-fed monopole antenna is designed for RFID applications. However the above proposed antennas are FR-4 substrate based, rigid ones and not suitable to mount on curved objects. WiMAX is allocated with the 2.5/3.5/5.5-GHz bands, and WLAN is allocated with the 2.4/5.2/5.8 GHz bands. The proposed antenna also works for the WLAN applications. Many designs have investigated and proposed to support WLAN/WiMAX standards. Design of RFID/WLAN antenna systems for microwave frequencies with compact, flexible, conformal considerations are very important (Liu, Ku, & Yang, 2010). So, design of low profile flexible patch antenna with conformability is needful to fulfill the requirements of RFID, bio-medical, industrial, scientific, medical (ISM) and wireless wearable devices. A dual band CPW-fed kapton polyimide substrate based antenna is proposed with two deformations (Mesquita, Pires, & Moreira, 2013) to study the performance characteristics, only single bent configuration is used to characterize this antenna. A CPW-fed patch antenna is designed with rectangular slots in (Niranjan, Saxena, & Srivastava, 2012), a polyflon polyguide substrate is used and it is a rigid one. Paper antennas are flexible antennas, most of the antenna designs are either complex or not compact. In (Kumar Naik & Sri, 2017; Kumar Naik & Sri, 2018) circular patch antenna has described for satellite communication.