circular polarized anteena

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how to design circular polarised anteena for FM band (88MHz to 108MHz)
thanks in advance
 

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
 

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.
 

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