the edge impedance is 300V. A quarter-wave transformer of Z0 = 173V is used to transform the impedance to 100V.
If the feed point is placed at 1 or 2, then LHCP or RHCP is obtained, respectively. For the feed at 1, VSWR and AR variation with frequency are shown in Figure 8.9.
The VSWR BW is 103 MHz (3.4%), but the AR BW is only 23 MHz (0.7%).
The VSWR BW of the antenna is much larger in comparison with a square MSA having two orthogonal feeds, whose BW is 54 MHz as described in Section 8.3.1.
This is because the reflected waves from the two edges of the patch are out of phase at the feed-point due to an additional l /4 length in one side, and hence are cancelled. However, the reflected
waves excite the opposite polarization, so ARBWdecreases.
Also, AR degrades due to the change in the phase of the feed line with frequency.