Parabola Calculator version 2.0

Small Version of Main Program Window

About This Program

This Freeware program was written to help you design solar collector or wifi projects using parabolic reflectors. Whether you're improving the signal strength of your wifi antenna, or designing a satellite antenna or solar trough, this program calculates the focal length and (x, y) coordinates for a parabola of any diameter and depth. It can help you determine what size and shape to make your parabola very quickly. Version 2 includes Wifi calculations for centered or offset feedhorn dishes. If you would like modifications to the program to make it more useful to you or to send feedback, you can email me here.


Thanks to Frank Schindler for the curve fitting code used by this program, you can see his page here.

Thanks to Bernhard S. Müller for helping develop and beta testing version 1, you can see his site here.

Thanks to Edisher Giorgadze for helping develop and beta testing version 2, you can see his page here.

Thanks to Paul Wade for supplying the WiFi text, calculations and code, they were copied directly from his hdl_ant program, you can visit his site and download his program here.

Download the Program

This program was written in Visual Basic 6, and should run on Window 95 or later. The program will run under Linux using Wine if you copy the dependancy files into the folder where the program resides. The program requires Visual Basic 6 runtime files, your computer may already have them installed. I would try downloading the smaller file (program only) first and seeing if it runs. If not, delete it and download the Windows Installer to perform a standard Windows installation.


Solar Action Alliance exists to educate visitors and provide them with opportunities to get involved with solar. This includes a petition, a blog full of informative articles, location-specific solar infographics, and much more!
Bernhard S. Müller's
La Cuisson Solaire
Welcome to ReCombinant Design!
The Solar Cooking Archive Wiki
The Wikia Parabolic Solar Reflectors Page
Paul Wade's N1BWT 10 GHz Page
The Third Paradigm (OT)

Program Notes

1.When you run the program you will see the main program window shown here. Use any units you like, as long as you use the same units for both the Depth and Diameter. You can also select Diameter and f/D as inputs using the Options > Select Inputs menu choice. I recommend using smaller units: inches instead of feet, or millimeters instead of meters, to increase the resolution of your measurements.

Main Program Window
2. After you enter some numbers into the Diameter and Depth text boxes and click the Calculate button, the program will show you the scaled down shape of the parabola you described, and it will calculate the (x, y) coordinates of the curve of the parabola in 16 straight line segments. You can calculate the (x, y) coordinates using anywhere from 2 to 1000 segments.
Enter Inputs into Main Program Window
3. To see what the shape and focal length would look like when the depth is increased to 18, hold down the horizontal scroll bar next to the text box and watch the parabola's shape change.
Change Inputs in Main Program Window
4. If you click the Save to Text File button, the program will prompt you to select a folder and enter a filename, and then it writes a file with the information you see in the text box on the right. Here's how the saved file looks when it is opened using Windows Notepad (using the Lucida Console non-proportional font where all characters have the same width so the columns line up vertically). The program will automatically suggest a filename that includes depth and diameter but you can enter any filename you like.
Saved Text File
5. If you'd like to see the coefficients of the Equation that describes the current Parabola, use the menu choice: File > View the Coefficients. You will see a message box like this one showing you the values used in the parabola equation:
Menu Choice to see Parabola Coefficients
Parabola coefficients
6. If you move your cursor over the image of the parabola, you will see the individual points calculated by the program: the (x, y) coordinates are shown at the bottom of the display. The point (horizontally) closest to the mouse cursor will be shown, you can see the location of each point listed in the text box.
Viewing the (x,y) coordinates on the Graphic
7. There are several file output formats you can use to save the data to a file that can be read by another program like ACAD, CorelDraw, or MS Excel. You can see these menu choices under the File menu.

You can print the graphic of the parabola to a printer using the Print menu choice.

You can change the foreground and background color of the Parabola graphic using the Options menu choice.

8. Wifi Calculations for centered or offset feedhorn dishes can be done using the Wifi Calculations menu choice.
Wifi Centered Feedhorn Calculations

Wifi Offset Feedhorn Calculations
9. If you'd like to read more about Solar Collectors and Solar Cooking Projects, or about the math behind Parabolas, click the menu choice:
File > Parabola and Solar Project Websites.
Click on a website and it will load into your default web browser automatically. Click the Hide button to view the main program form again when you're finished with the web sites. A collection of these links can be found here.
Web Sites About Parabolas