Horn Antenna Design in CST MWS

 Horn Antenna Design in CST MWS

Objective: To understand, design horn antenna and observe the simulated results.

Antenna-Theory: It is a type of antenna in the shape of helix. Its polarization and radiation properties depend on the diameter, pitch, number of turns, wavelength, excitation and spacing between the helical loops. Helical antenna consists of helical loops made of thick conductor which give the appearance of screw thread. 

Fig. 1.1 Horn antenna

Step 1. Parameter Calculation 

The center frequency of the required helical antenna is 3 GHz. However the coil radius, coil height, number of turns of coil and angle increment is shown below in table.

Fig. 1.2 Design values of horn antenna

Step 2. Designing 

As you have list of parameters it's time to design the horn antenna in CST software. For that you need to perform following minor steps. All of these highlighted steps are already explained in half wave dipole antenna design tutorial. 

1. Create new project.

2. Select Antennas.

3. Click on horn.

4. Select time domain.

5. Enter frequency range.

6. Final Summary. 

After creating a CST MWS project for horn antenna. Now construct a waveguide model by selecting using brick tool. All of the values are mentioned in table.

Fig. 2.1 Constructing a waveguide model

Now construct a square shape surface of 2mm thickness called horn just away from the waveguide.

Fig. 2.2 Constructing a horn surface

Now pick the front face of waveguide and back face of horn surface and use loft option. This can be seen in image below. 

Fig. 2.3 Creation of Wave guide

Now add these 3 parts together using boolean operation. 

Fig. 2.4 adding the parts 

In order to excite the antenna there must be a path in waveguide so a cut should be introduced at backside of waveguide and at front side of rectangular surface. This can be done by using pick face option and curve tools>>shell or thicken solid sheet. The thickness can be 1mm and it should be inside always.

Fig. 2.5 Cutting the parts for excitation

To excite the antenna you need to select the back side of waveguide and use pick face option. Select the outer boundary of  antenna waveguide as shown below in image.

Fig. 2.6 Selecting boundary

Now use a waveguide port and apply for simulation.

Fig. 2.7 Waveguide port 

Again click on cylinder tool to make the outer conductor around the dielectric material. Use the values mentioned in table.

 

Fig. 2.10 Simulating the antenna

Step 3. Results 

Fig. 3.1 S11 of Horn antenna