A flexible, spiral-shaped frequency reconfigurable antenna with a compact size (20 × 24  mm²)
is presented. The proposed antenna has a low-profile planar structure
and is able to operate at five different frequency bands, i.e.,
4.19–4.48, 5.98–6.4, 3.42–4.0, 5.4–5.68, and 6.8–7.0 GHz. The multiband
operation enables the antenna to cover aeronautical radio navigation,
fixed satellite communication, WLAN, and WiMAX standards. A radiating
element is backed by Rogers® 5880 substrate with a thickness of 0.508 mm
and dielectric constant of 2.2. The spiral shape is achieved by
introducing different strips. Frequency reconfiguration is achieved by
the incorporation of a lumped element in a strip, so that the antenna
can switch between different resonances. To validate the performance of
the antenna, the prototype of the design was fabricated and tested. Good
acquiescent is seen between simulated and measured results. The
proposed antenna operates efficiently with appreciable return loss,
directivity, bandwidth, and peak gain.