Compact and tunable slot-loop antenna

Pei-Ling Chi*, Rod Waterhouse, Tatsuo Itoh

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


A compact and tunable slot-loop antenna is studied in this communication. By periodically loading the slot line with varactor diodes, the slow-wave loop is capable of operating at frequencies from 2.34 GHz to 4 GHz with the measured input reflection coefficient better than -7.5 dB while occupying a small footprint of 0.072 λg × 0.072 λg (8.1 mm × 8.1 mm), where λg is the guided wavelength of a slot line at 2.34 GHz. The slot-loop in the ground plane is excited by a simple microstrip line, which enables the impedance matching from 3.2 GHz to 4 GHz for VSWR ≤ 2. A LC low-pass circuit is configured into the bias network to isolate the RF signal from the DC power path and consistent radiation patterns are experimentally obtained across the entire tunable frequencies of interest. The slot loop combined with the feed line and the bias circuitry is only 40 mm × 38.97 mm. Experimental results validate the feasibility of the presented antenna and agree well with simulation data.

Original languageEnglish
Article number5705552
Pages (from-to)1394-1397
Number of pages4
JournalIEEE Transactions on Antennas and Propagation
Issue number4
StatePublished - 1 Apr 2011


  • Compact antenna
  • slot-loop
  • tunable antenna

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