0 = 2.904 GHz. However, the AR increases slightly within the VSWR BW
as shown in Figure 8.4(b).
When a thick substrate with a low dielectric
constant is used, the VSWR BW of the antenna further increases.
For a square MSA with L = 4.5 cm, e r = 1, h = 0.5 cm, with two orthogonal
feeds at x = y = 1.4 cm, the VSWR BW increases to 230 MHz (7.7%), but
AR increases from nearly 1–3 dB as frequency increases as shown in Figure
8.4.
The increase in AR is due to the increase in the undesired radiation
from the increased probe length.