Antenna Matching at Harmonic Frequencies to

Analysis of a self-resonant, dual-frequency-matched antenna is presented. The operating frequencies of the antenna are harmonically separated, and 1-GHz fundamental and 2-GHz second harmonic frequencies are used. This type of antenna can be used, e.g., in harmonic transponder applications, where the antenna is loaded with a nonlinear element, which is typically a Schottky diode. In this letter, the impedance properties of the studied antenna are investigated using an example Schottky diode. Compared to conventional 50- environments, the frequency-de- pendent impedance of the Schottky diode provides additional challenges for antenna matching, which are also addressed. Rather than providing a design for an application-specific antenna, the current study presents certain "buildin gb locks" that may be useful for particular antenna designs. Index Terms—Antenna, diode, harmonic frequency, impedance matching, radio frequency identification (RFID), self-resonant, transponder.