Single Layer Multi-Band Transmissive Type Linear to Circular Polarization Converter With Wide Angular Stability for C-, X-, and Ku-Band Applications

This paper presents a Linear-to-Circular Polarization Converter (LCPC) used for multi-band functionality. The LCPC surface features symmetrically printed copper strips on a single-layer substrate and is surrounded by a square Substrate Integrated Waveguide (SIW) cavity arranged periodically in two dimensions. The study successfully utilizes the LCPC surface to achieve a desirable Axial Ratio (AR) Band Width (BW) below 3 dB in multiple frequency ranges, specifically: (i) 4.51-4.80 GHz, (ii) 6.51-6.80 GHz, (iii) 9.01-9.20 GHz, (iv) 10.90-12.40 GHz, and (v) 17.05-17.49 GHz. The LCPC induces a change in polarization as the wave propagates through it. In the first (f(31)) and fourth (f(34)) frequency bands, the initially Linearly Polarized (LP) wave transforms into a Left-Hand Circularly Polarized (LHCP) wave. Conversely, in the second (f(32)), third (f(33)), and fifth (f(35)) frequency bands, the wave converts into a Right-Hand Circularly Polarized (RHCP) wave. Measurement results indicate that the LCPC provides Circularly Polarized (CP) wave bandwidths of 12.72%, 4.8%, 2.4%, 11.39%, and 3.15% across frequency ranges of 3.9 - 4.43 GHz, 6.21- 6.52 GHz, 8.9-9.08 GHz, 10.51-11.78 GHz, and 16.85-17.39 GHz, respectively. This characteristic renders the LCPC suitable for utilization in the C (4-8 GHz), X (8-12 GHz), and Ku (12-18 GHz) frequency bands.