circular polarized anteena

The usual way is to have two linearly polarized antennas mechanically rotated to be 90 degrees apart. Then the feed points are fed with a 90 degree phase difference.

The old turnstile dipole antenna was circular in the direction perpendicular to the plane the elements were contained in.

another way is the use of helical antennas.
A left handed (left means the same sense of the screw) wound wire helical do transmission and receiving LHCP

There are software to design circular polarized antenna's from http://www.vectorfields.co.uk/. Any kind. Pat-ch antenna for example;

just to add an info about BandWidth.
108/88 = 1.22 ... a quarter of octave. It is wide enough, you may accect some compromises on performances. The axial ratio ( a figure of goodness of polarization) may reach up to 1 dB at the band edge.