A reconfigurable
circularly polarized antenna is proposed and developed in this letter. The
proposed circularly polarized antenna consists of two linearly polarized
inverted-L antenna elements with double-folded arms. To improve impedance
matching and radiation characteristics the double-folded structure plays a
significant role. Circular polarization is achieved by properly adjusting the
lengths of two arms, quadrature currents can be produced on two orthogonal
elements. The proposed linearly polarized antenna elements are low-profile and
small in size, the proposed circularly polarized antenna is about 34.5mm in
lateral size and 18mm in height. The feeding configuration is simplified by
using coaxial probe instead of an external polarizer. Better values are
obtained between the simulated and measured results, which validate our design
concept. The measured results show that the circularly polarized antenna has a
wide impedance bandwidth of 6% and a 3-dB axial ratio (AR) bandwidth of 1.16%.


Index Terms—Circularly
polarized antenna, double folded arm antenna, inverted-L antenna.

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 The circular polarization provides reduction in
multipath effect and flexibility in the orientation angle between a transmitter
and a receiver hence  CIRCULARLY
polarized (CP) antennas are compatible for radar tracking, global positioning
system, satellite communication, radio frequency identification, and sensor


polarized antennas with compact size have been developed for portable and
mobile terminal applications In recent years. Most of them are circularly polarized
microstrip antennas (CPMAs) with high-dielectric material substrate owing to
their low profile, easy manufacture, and light weight.

Slotted and
folded patch structures are also introduced to construct small CPMAs. However,
their main disadvantages are extremely narrow bandwidth and decreased radiation
efficiency 1–5.