any one help me how increase bandwidth of patch antenna using cst
Hi..
Bandwidth BW=f0/Q, where f0 is the freq of resonance and Q is the Quality factor..
Q=2*pi*Energy stored/Energy dissipated per cycle..
Therefore one way to increase BW is to decrease Q, i.e. *either by decreasing stored energy, or by increasing losses.
a) Decreasing stored energy: i) By increasing substrate height and ii) by reducing dielectric constant (which you told you can't change). Both these methods increase the fringing and hence reduce the energy stored in microstrip resonator.. However careful!! Increasing substrate height can excite unwanted surface waves.
b)Increasing Losses: i) By introducing losses in dielectrics (Which you told you won't alter) ii) By introducing Chip resistor.. However, introducing chip resistor and thus introducing losses reduces the gain, which can be elevated using superstrates.
c) Using multi-mode techniques: Many resonant modes can be stagger-tuned together to have large BW..by i) having stacked elements ii) having coupled parasitic elements iii) or by introducing*slots which individually introduces resonances which can be near enough together to form a wider band.
You can refer:
a) Microstrip antennas (Garg et al.) *b) Compact and broadband microstrip antennas (Wong) c) Microstrip patch antennas (Lee, Luk)
Thanks