The impedance bandwidth (for VSWR [less than or equal to] 2) referenced to the input resonant resistance
of the antennas varies from 0.8% to 4.2% and it is directly proportional to the d/Lhel ratios of the antennas [Figure 6].
The calculated radiation resistance for analysed structure is equal to 180 [ohm], whereas the resonant resistance
of the same patch fed by short (about 1% of the patch length) microstrip line, simulated in ADS Momentum equals 169 [ohm].
R is the resonant resistance; QT is the Quality factor, f is the operating frequency and [f.sub.r] is the resonant frequency.
The resonant resistance is calculated using equation (3) as in :
There is good agreement between the measured resonant resistance
and the simulation.
Observe the resonant resistance
and try to maximize its value.
Just like Section 3.1, in circularity polarization antenna array, the resonant resistances
of two polarizations in one antenna are affected by coupling differently, so the matching and axial ratio will be worse.