Foldable Circularly Polarized Tightly Coupled Dipole Array for High Resolution Radars

A foldable wide band circularly polarized Tightly Coupled Dipole Array (CP- TCDA) is presented for high resolution spaceborne radars. For the first time, we propose a wideband circularly polarized array based on the TCDA concept. The design employs orthogonally placed dipoles, and incorporates strategically positioned capacitive pads. Orthogonally oriented dipoles are connected through inherently concentric
$90^{\circ}$
phase shifters. Further, the array is highly conformal with the ground plane, placed at close proximity of the array plane. The array uses a combination of rigid and flexible substrates to adopt accordion-like folding. This foldable CP- TCDA provides an impedance bandwidth of VSWR < 3 from 103 MHz to 408 MHz, and an axial ratio of < 3 dB from 160 MHz to 320 MHz.