UWB Circularly Polarized Coax-Fed Spiral Slot Antenna

A design of a circularly polarized (CP) coax-fed spiral slot antenna for ultra wide band (UWB) applications is introduced. In the presented structure, an Archimedean spiral shaped radiating element is utilized in order to produce the UWB CP functionality. In order to reducing the antenna size, number of spiral turns, and the reflected energy, chip resistor is used to dissipate the energy at the end of the arm. Although by added spiral slotted ground plane, deforming at the bottom of the designed antenna, the reflected energy is existed, and much wider bandwidth can be produced, especially at the lower bands. The proposed antenna radiates a bidirectional wave with the opposite CP. To accredit the simulation results, the prototypes of the suggested antenna are constructed on an inexpensive FR-4 substrate and tested. The measured results exhibit a 156% (10.74 GHz, 2.16–12.90 GHz) 3dB axial-ratio (AR) bandwidth, and the 10-dB impedance bandwidth is 175% (12.00 GHz, 1.10–13.10 GHz).

Keywords:

Circular polarization (CP) , spiral slot antenna , ultra wideband (UWB)