Advances in direct-write printing technology have enabled printable electronics practically on any substrates including paper. Paper is a material of very low cost, it is extremely flexible, and can be post-treated to obtain hydrophilic or hydropho-bic characteristics. Organic paper substrates have recently found extensive use in the development of antenna components. Many designs with different characteris-tics and for various applications have been made. In this chapter, a comprehensive description of printing technologies and recent dielectric measurements for paper substrates are described. Then, the time and frequency evolution of antennas on hydrophobic and hydrophilic paper substrates are presented. Antennas are approached from a principle of operation perspective and emphasis is given on their characteristics and the applications that span from omnidirectional radio fre-quency identification, WLAN and ultra-wideband antennas to recently developed QR code antennas for anti-counterfeiting and security applications
