Fig. 3 shows the geometry ofthis antenna, and Fig. 4 shows
its practical realisation. The two patches are coplanar and
individually shorted to ground by a shorting pin. The antenna
is air tilled, and has a maximum thickness of IOmm. This is
about 1/15 of a free space wavelength at the frequency of
interest, while the maximum transverse dimension is only a
quarter-wavelength. The driven patch has dimensions 22 x
30mm, while the other is about 8 x33 mm. A rectangular stub
measuring 2 x 3.25 mm' is attached to the centre of the
radiating edge of the driven patch, and is also attached to the
feed probe. For optimal coupling, the coupling gap between
the two shorted patches is about 4mm. The radius of the
shorting pins and the feed probe is 0.65mm