Where To Find This Example
AWR Version 14
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AWR Version 13
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Coax Fed Patch Antenna with Waveport at Different Location
This example demonstrates the use of a coaxial probe-fed rectangular microstrip patch antenna. Analyst’s finite element wave ports are used to drive the antenna and radiation patterns and feed return loss and input impedance are calculated.
This project does not include the datasets, therefore simulating this project will take approximately twenty minutes. However this example is available with datasets at : http://kb.awr.com/display/Examples/Coax_Fed_Patch_Antenna
The design is a coaxial probe-fed rectangular microstrip patch antenna on a finite dielectric substrate and a finite ground plane. Perfectly Matched Layer (PML) boundary conditions are used on the 3D enclosure except for a circular region through which the coax line feeds the antenna. Principal plane radiation patterns at Phi equals 0 and 90 degrees are plotted at 7.8 GHz along with the feed return loss and input impedance.
This example also demonstrates how the finite dielectric substrate is setup in the 2.5D layout environment in Microwave Office. This is done by mapping the drawing layer “+LAY_3_SubFinite_COND” with a dielectric material “SubFinite”. It should also be noted that the finite ground is drawn with a circular hole. Move the “Coaxial_Feed” in 2D layout view to see the hole. Without this hole, the Coax feed would be short circuited.
Understanding Analyst Wave Port Calculations in the EM Structures
“ExtendedCoax” - this is the structure where the wave port solution includes only the cross-section of the coax line with its TEM mode. Since the lower boundary of the 3D structure is a PML the radiating fields fringe around the bottom face resulting in a significant back lobe in the radiation pattern graph.
The “ExtendedCoax” setup is therefore a better real-world arrangement, whereas the “TouchingBoundary” document shows the behavior of Analyst’s wave port solution.
Radiation pattern measurements
The total power far field radiation pattern measurement is found under Electromagnetic > Antenna > Sweep Theta > PPC_TPwr. Phi=0 gives the XZ plane cut, and Phi=90 gives the YZ plane cut. The graphes show the directivity patterns as none of the two options for including losses is checked.
EM Structure - ExtendedCoax
EM Structure 3D - ExtendedCoax
Graph - Return Loss in dB
Graph - Principal Plane Phi at 0 degrees