Compact CRLH asymmetric-CPS resonant antenna with frequency agility

Shih Chia Chiu, Liang Yu Ou Yang, Chien Pai Lai, Shih Yuan Chen

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


A compact, uniplanar composite right/left-handed transmission line (CRLH TL) resonant antenna with frequency agility is proposed based on the asymmetric coplanar strip (ACPS). First, it is shown that a capacitor as the termination for an unbalanced CRLH ACPS is needed for excitation of an anti-resonance within the frequency range between the zeroth-order series and shunt resonances. The design formula to estimate the value of the termination capacitance for a given resonant frequency is derived as well. By utilizing a varactor diode as the termination, the termination capacitance can be controlled by changing its bias voltage, and the resonance of the antenna can thus be tuned between the two zeroth-order resonant frequencies. For verification, a prototype antenna was fabricated and tested. It has a continuously tunable resonant frequency between 2.15 GHz and 2.8 GHz as the bias voltage is adjusted in between 4 V and 22 V. When tuned to resonate at different frequencies in between the two zeroth-order resonances, the antenna still exhibits similar slot-like radiation pattern and stable peak gain and radiation efficiency owing to the same resonant mechanism in the frequency range.

Original languageEnglish
Article number6656819
Pages (from-to)527-534
Number of pages8
JournalIEEE Transactions on Antennas and Propagation
Issue number2
StatePublished - Feb 2014


  • Band gap
  • composite right/left-handed transmission lines (CRLH TLs)
  • coplanar strips


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