Modal Analysis of Circularly Polarised Hexagonal Patch Antenna

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Prakash Karavilavadakkethil Chellappan, Remsha Moolatt , Vinisha Chaluvayalil, Vasudevan Kesavath


The modal analysis and confirmation of Circular Polarisation (CP) behaviour of a hexagonal  microstrip patch antenna antenna with polygonal slot is presented. This work is an extended analytical study of a published paper by one of the authors above. The antenna geometry includes a regular hexagon shaped patch with a polygonal slot at the centre, which accounts for circular polarization.  It is fabricated on FR4 substrate with size of 50 mm x 50 mm x 1.6 mm and a dielectric constant 4.4. Two antenna prototypes, one is Left hand Circularly Polarised (LHCP) and the other Right Hand Circularly Polarised (RHCP) were fabricated. The measured results include 10dB impedance bandwidth of 5.5 % at the center frequency of 2.42 GHz, a return loss of 32 dB, minimum axial ratio of 1.82 dB, axial ratio bandwidth of 7.5%, for the proposed RHCP and LHCP antennas. The axial ratio bandwidth was measured to be 180MHz (7.43%) for RHCP antenna and 181.2 MHz for LHCP antenna prototype (7.42%). The gain of the RHCP and LHCP antenna protypes were measured using gain comparison method. The RHCP antenna gives a maximum gain of 4.9 dBi at the frequency 2.42 GHz   and the LHCP antenna, 4.91 dBi at 2.44 GHz. Efficiency of 89.9% was achieved for both antenna prototypes. These results are well in tune with the simulated results and the proposed design is suitable for RFID reader antenna applications.

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