Circularly Polarized Curl Antenna for Time Modulated Frequency Diverse Array with Linear and Orbital Angular Momentums

In this paper, a novel technology called time modulated circularly polarized frequency diverse array (TMCFDA) is presented which combines the advantages of time modulated frequency diverse array (TMFDA) and polarization array sensitivity. Target tracking can be achieved by creating a pencil-shaped time-invariant and range-angle dependent beampattern using a broadband circularly polarized curl antenna element. A circular array consists of three rings of curl antenna array is used to enable the detection of single target at 10GHz. The curl has spiral constant $a=0.18 \mathrm{~mm} / \mathrm{rad}$ with height of $3.2 \mathrm{~mm}$. The start angle $\Phi$ is chosen to be $6 \pi \mathrm{rad}$ and the end at 26.3rad. A coaxial cable with a $50 \Omega$ impedance is utilized for feeding the antenna. The operating frequency of the antenna is set at 10GHz, for FDA radar applications. For target detection, three targets located at different distances and directions i.e. $\left\{\left(r_{s}, \theta_{s}\right) \mid s=1,2,3, \in\left(400 \mathrm{~km}, 10^{\circ}\right),\left(600 \mathrm{~km}, 0^{\circ}\right),\left(800 \mathrm{~km},-24^{\circ}\right)\right\}$ for linear array and i.e. $\left\{\left(r_{s}, \theta_{s}, \phi_{s}\right) \mid s=1,2,3, \in\left(400 \mathrm{~km},-20^{\circ}, 70^{\circ}\right),\left(600 \mathrm{~km}, 0^{\circ}, 130^{\circ}\right),\left(800 \mathrm{~km}, 30^{\circ}, 100^{\circ}\right)\right\}$ for circular array are considered for fundamental, $1^{\text {st }}$ harmonic and $2^{\text {nd }}$ harmonic components, respectively. Curl antennas are investigated and analyzed using CST Microwave Studio. Integration of the vortex electromagnetic wave theory with the TMCFDA structure is studied.