Microstrip Patch Antenna and Coplanar Waveguide

patch antenna waveguides

hi,i am new to hfss.i have never used it before.can somebody plz help me with CPW and lumped ports.i am quite good at it when it comes to theoretical knowledge of antennas but need help with using hfss

coplanar waveguide patch antenna

Hi Saquib,
conventional CPWs can be fed with either wave ports or lumped ports. Lumped port are more suitable when you need internal ports. In such a case, lump.ports have to be square, with the sides having the same width of CPW signal line. The port must touch the CPW signal line at one side and the surrounding CPW ground at the opposite side (used as terminal reference). Current vector must be set along the direction of CPW line. You can get input impedance, but for S params calculation you need to know the Z0 line. It can be obtained from a simulation of the line fed with a wave port. Draw a rectangle centered at CPW line. Choose a width of 4-5 times of 2*CPWgapWidth+CPWlineWidth and an height of 4-5 times the substrate thickness for the port. It must be placed at the face of the airbox enclosing the structure to be simulated. The wave port must touch the non-material background at one face and the CPW on the other face. Be careful of wave port size. Too big wave ports may cause undesired higher order modes to be excited. Too small ports affect the port characteristic impedance since a significant part of fundamental mode lines of force could be truncated.
The obtained real portZ0 can be considered as the characteristic impedance of the CPW line. This impedance can be set as port reference impedance for the internal lumped port of the previous model. If all is correct, differences in input impedances and S params are negligible. In general, use an airbox surrounding the structure with radiation boundaries applied to keep into account for radiation effects. The airbox must be spaced of at least lambda0/4 from each surface of CPW.

As for ustrip patch antennas, enclose the structure into an airbox with radiation boundaries too, and use wave ports for feeding the antenna. The settings for the port are similar. The wave port lower limit is the ustrip ground plane and it's usually high 5 or 6 times the substrate thickness and 6 to 8 times the feeding ustrip width. Moreover, define far field infinite sphere for far field result plots.

Hope this helps.

Ivan