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# Analysis of Basic Delta Loop Antenna over Ground

This example shows how to analyze the performance of a delta loop antenna over a metal ground. The length of the antenna is λ/3 on each side of the triangle, where λ is the wavelength. Equilateral delta antennas are single-band high frequency (HF) antennas. You vary the baseline parameters of an antenna such as the length and height above the ground to optimize antenna performance [1].

### Define Basic Dimensions of Shape

Create the delta loop antenna using defined geometry parameters. Use strips instead of wires to create the antenna. Use the `cylinder2strip` function to calculate the equivatent strip dimesnions.

```wireRadius = 1.5e-3; stripWidth = cylinder2strip(wireRadius);```

### Create Triangular Strip

Create a triangular strip using a circle shape. Define inner and outer radii. Create circles with three points each using the calculated radii.

```otRadius = 0.5774*15.06; % Outside radius of circumcircle of triangle inRadius = 0.5774*(15.06-stripWidth); % Inside radius of circumcircle of triangle (less than outside radius by strip width) ot = shape.Circle(Radius=otRadius, NumPoints=3); % Outside Triangle in = shape.Circle(Radius=inRadius, NumPoints=3); % Inside Triangle```

Create a metal strip by subtracting smaller triangle from the larger one. Rotate the strip vertically to place it over the flat ground.

```triStrip = ot - in; % Triangular strip show(triStrip) title("Triangular Metal Strip");```

`[~] = rotate(triStrip,90,[0 0 0],[0 1 0]);`

### Add Metal Ground

Create a metal ground and place the strip above the ground. Add two shapes and visualize the resultant shape.

```gnd = shape.Rectangle(Length=60,Width=60); [~] = translate(gnd,[0 0 -24.5]); ant = triStrip + gnd; show(ant) title("Triangular Metal Strip over Ground");```

### Create Delta Antenna

Use the `customAntenna` function to convert the triangular metal strip with ground to an antenna. Add feed to this antenna at a desird location.

```ca = customAntenna(Shape=ant); ca.createFeed([0,0,-8.0819],1); show(ca)```

### Analyze Delta Antenna

Calculate and plot the reflection coefficient and impedance of the delta antenna.

#### Plot Reflection Coefficient

Plot the reflection coefficient for this antenna over the 5 MHz to 10 MHz frequency band with a reference impedance of 50 ohms.

```sparam = sparameters(ca,linspace(5e6,10e6,200)); rfplot(sparam); title("Return Loss of Delta Loop over Metal Ground");```

#### Plot Impedance

Calculate and plot the impedance for this antenna over the 5 MHz to 10 MHz frequency band. The reactance is close to zero at 7 MHz.

```impedance(ca,linspace(5e6,10e6,200)) title("Impedance of Delta Loop Antenna over Metal Ground");```

### Conclusion

In this example, you build and analyze the basic structure of the delta loop antenna over a metal ground. The results closely match to the design expectation.

### References

[1] Herwade, Pranita A., and Sandeep V. Gaikwad. “Design of Broadband Delta Loop Antenna and Balun for Ionosonde Application.” In 2015 Annual IEEE India Conference (INDICON), 1–5. New Delhi, India: IEEE, 2015. https://doi.org/10.1109/INDICON.2015.7443498.