Omnidirectional Loop Antenna With Left-Handed Loading

This letter presents an omnidirectional horizontally polarized planar printed loop-antenna using left-handed CL loading with 50-Omega input impedance. The antenna has a one wavelength circumference and gives an omnidirectional pattern in the plane of the loop, whilst working in an
n
= 0 mode. In contrast, a conventional right-handed loop, with the same dimensions, has a figure of eight pattern in the plane of the loop. The antenna is compared with other right-handed periodically loading loop antennas and shown to have the best efficiency and is much easier to match. Design details and simulated results are presented. The concept significantly extends the design degrees of freedom for loop antennas.