Novel broadband angular stable linear‐circular and linear‐cross polarizer based on inductive grid loaded H‐dipole in both reflection and transmission modes

Abstract

A novel broadband linear‐circular and linear‐cross polarization converter for K to Ka‐band applications is demonstrated in this work. The proposed structure primarily consists of an inductive grid in orthogonal with an H‐shaped dipole as top Frequency Selective Surface (FSS) and a modified horizontal dipole as bottom FSS; a 1 mm thin FR‐4 substrate is separating both. During transmission, it can convert the linearly polarized EM wave to a circular one, with Axial Ratio (AR) ≤ 3 dB from 13.08 to 25.13 GHz with 63.07% Fractional Bandwidth (FBW). In addition, this polarizer can work in reflection mode also when the bottom FSS is replaced by a Perfect Electrical Conductor (PEC), demonstrating the linear‐circular polarization with AR (≤3 dB) from 16.94 to 18.64 GHz (RHCP/LHCP) and 24.5–40.32 GHz (LHCP/RHCP) with FBW 9.56% (Ku‐band), and 48.81% (K‐ and Ka‐band), respectively. Besides, linear‐circular conversion, it performs linear‐cross conversion in reflection mode with polarization conversion ratio (PCR) above 90% from 19.71–22.22 GHz, 43.57–48.81 GHz, 53.50–55.32 GHz with 13.89%, 11.34%, 3.32%, FBW, respectively. The equivalent circuit model of the proposed converter is extracted. Surface current distribution profiles at multiple plasmonic resonances are investigated to understand the reason behind the multi‐polarization conversion. The performance is angular stable up to 45° for both transverse electric (TE) and transverse magnetic (TM) incidences for reflection as well as transmission modes. The unitcell is compact with periodicity 0.114λL × 0.114λL and a thickness of 0.044λL, where λL is the free‐space wavelength of the lowest frequency. This design's novelty lies in dual‐mode stable angular performance in both reflection and transmission cases. Also, highly miniaturized architecture and circular rotation switching in the consecutive bands make this design suitable for real‐time scenarios.

Novel miniaturized arrow linked figure of eight square loop FSS-based multiband linear-circular and linear-cross reflective microwave polarizer

“…8, the induced surface currents are antiparallel for the top FSS and ground plane at 5.05 and 8.85 GHz resembling the magnetic or dielectric resonance. In contrast, the currents are parallel for the 15.95 GHz case, resulting in electric resonances [9].

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“…Controlling the propagation states of EM waves has been reported in reflection and transmission modes over the EM spectrum [10]. A compact, high-efficiency microwave linear-cross polarizer based on square split rings is demonstrated [9], with unity cross-pol reflectance from 8.2 to 23 GHz. Huang et al .…”

“…Frequency selective surfaces (FSSs) are the 2D-spatial filters that possess advantages like planar nature, low profile, and fabrication ease [8]. The advancement of FSS technology has drawn researchers' attention in modulating the EM wave features like amplitude, phase, and polarization states using FSS [9]. Controlling the propagation states of EM waves has been reported in reflection and transmission modes over the EM spectrum [10].…”

“…Controlling the propagation states of EM waves has been reported in reflection and transmission modes over the EM spectrum [10]. A compact, highefficiency microwave linear-cross polarizer based on square split rings is demonstrated [9], with unity cross-pol reflectance from 8.2 to 23 GHz. Huang et al proposed an ultrathin dual-band reflective polarizer that performs linear-cross conversion in frequency ranges 4.40-5.30 GHz and 9.45-13.60 GHz [11].…”