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The microstrip patch antenna is a popular printed resonantantenna for narrow-band microwave wireless links that require semi-hemisphericalcoverage. Due to its planar configuration and ease of integration withmicrostrip technology, the microstrip patch antenna has been heavily studied andis often used as elements for an array. In this tutorial, a 2.4 GHz microstrippatch antenna fed by a microstrip line on a 2.2 permittivity substrate isstudied. The following topics are covered:.Model Setup.Waveport Feed.Airbox and Boundary Conditions.Meshing.Analysis/Sweep Setup.Plotting Results.Experimental Results and Photos of the Fabricated Antenna are.
Waveport SetupIn order to excite the structure an excitation source hasto be chosen. For this simulation a waveport will be used. The waveport willexcite the first mode of the microstrip line (quasi-TEM) and then HFSS will usethis field to excite the entire structure. In order to get an accurate result,the waveport has to be defined properly; if it is too small the field will betruncated (characteristic impedance will be incorrectly calculated) and if it istoo large a waveguide mode may appear.
Design Of Microstrip Patch Antenna
Please refer to the tutorial on defininga waveport for further information. Since the substrate height is 1.57 mm andthe feed line width is 4.84 mm, the waveport size chosen is 5 mm high by 50 mmwide.
After the waveport rectangle is drawn, the WAVEPORT excitation wasassigned to it. In the Analysis section of this tutorial, it will be shown thatthis waveport size accurately models the desired microstrip mode. Airbox and Boundary ConditionsAn airbox has to be defined in to model open space so that the radiation fromthe structure is absorbed and not reflected back.
The airbox should be aquarter-wavelength long of the frequency of interest in the direction of theradiated field. In the directions where the radiation is minimal, thisquarter-wavelength condition does not have to be met and an air “space” may noteven have to be defined. Since the radiation of a patch antenna is concentratedat broadside, a rectangular box enclosing the structure is only needed; theheight of the airbox is 31.25 mm (quarter-wave at 2.4 GHz). The antenna withairbox and waveport setup is shown in Fig. Patch antenna layout showing airbox and waveport.Next, the 4 side faces and the top face of the airbox wereselected (Press F to select faces and O to select objects) and RADIATIONboundary was applied.
Then the bottom face and the patch antenna trace wereselected and a FINITE CONDUCTIVITY boundary using Copper was assigned. MeshingManually meshing should be performed on the airbox to get accurate resultsfor the antenna properties such as efficiency, directivity, and radiationpattern. One should seed the airbox lambda/10. For this structure the initialmesh length for the airbox was set to 12.5 mm (lambda/10 at 2.4 GHz). 3shows the mesh property window. Mesh setup window.
Analysis/Sweep SetupA Solution Setup is added to the analysis of the simulation with thefollowing:Solution Frequency: 2.4 GHzMaximum # of Passes: 15Maximum Delta S: 0.02In addition, in the Options tab of the Solution Setup, the Minimum ConvergedPasses was changed to 3. Since a Fast Sweep from 1 GHz to 5 GHz (401 points)will be chosen, the solution frequency should line within the frequency sweeprange and around the passband (i.e, around 2.4 GHz). In addition, the field datais saved for each frequency point in the sweep; field data needs to be saved inorder to do any field post-processing.Before running the simulation, an additional Solution Setup was added with SolvePorts Only to verify the waveport setup. This Port Only Setup was run and theresulting port mode is shown in Fig. 4; a characteristic impedance of 50.7 Ohmswas obtained. E-field distribution on antenna at 2.36 GHz.To plot the far-field patterns of the antenna, a far-fieldsetup has to be created.
Two will created; one for the E- and H-Planetwo-dimensional patterns and another for the three-dimensional pattern. Tocreate each far-field setup go to HFSSRadiationInsert Far-Field SetupInfiniteSphere.
For the two-dimensional pattern, the default values have to be changed;Phi should start at 0 deg and stop at 90 deg with a 90 deg step size. For thethree-dimensional pattern, the default values can be used. 7 shows thetwo-dimensional patterns and Fig. 8 shows the three-dimensional patterns.
Rectangular Patch Antenna Array Design At 13 Ghz Frequency Using Hfss
Toobtain the radiation efficiency, peak gain, etc. Go to HFSSRadiationComputeAntenna/Max Param and choose 2.36 GHz as the frequency of interest.