C‐Band Linearly Polarised Textile‐Reflectarray (TRA) Using Conductive Thread

Abstract

A linearly polarised C-band textile-based reflectarray (TRA) is designed and fabricated using conductive thread. Three fabric samples are selected to be employed in the TRA design. The relative permittivity of the samples under test are extracted using resonance technique. The extracted material parameters are used in designing TRA elements. The reflected wave amplitude and phase curves are obtained by varying the size of the radiating element, resulting in a 340° reflected phase, which is adequate to design the C-band TRA. A centre-fed TRA consisting of 15×15 elements, with antenna size of 8.25λ×8.25λ is intended for the analysis of broadside radiations. A wide band multi-layer stacked circular patches are used as a feeder. The radiating elements of the TRA are made using the laying technique with conductive thread. The ground (GND) plane is made of shielded fabric. During measurements, it is observed that the shielded fabric is not suitable to be used as a large ground plane. The TRA antenna is measured at 5.8 GHz. The antenna provides a 1-dB gain bandwidth of 9.3%, the 3-dB gain bandwidth of more than 22%, SLL of -16 dB, and cross polarisation of -21 dB. A measured total field amplitude and phase distribution verify the planar wavefront conversion from the TRA.