A dipole antenna is a basic radio antenna made of two conductive elements fed at the center. It is typically a half-wavelength long and is widely used as a reference antenna in antenna theory and practice.
Dipole antennas work by converting alternating current into electromagnetic waves. Their radiation pattern is strongest perpendicular to the antenna and weakest along its axis, forming a donut-shaped pattern in three dimensions.
The orientation of a dipole antenna determines its polarization. A horizontal dipole produces horizontally polarized waves, while a vertical dipole produces vertically polarized waves. Matching polarization improves signal strength.
A half-wave dipole has an impedance of about 73 ohms in free space, which closely matches common coaxial cables. Proper impedance matching improves efficiency and reduces signal reflections.
When a dipole is installed close to the ground, near objects, or in an inverted-V shape, its impedance naturally drops from ~73 ohms toward 50 ohms. Many real-world dipoles end up near 50 ohms without extra components.
A folded dipole has about 300 ohms impedance, but using a 4:1 balun converts it to 75 ohms, and further matching can bring it to 50 ohms if needed.
Common types include half-wave, folded, short, and inverted-V dipoles. Dipole antennas are used in FM radio, television, amateur radio, and as components of directional antenna arrays.
My Antenna
Below is the antenna I made and tested. This video will show you how I did it, and why. I share some tips I learned along the way. But I would also value your thoughts.
The app I used to get the measurements from is this one:
https://play.google.com/store/apps/details?id=com.daveyhollenberg.amateurradiotoolkit
However you can get lots of different apps that will do this. Or you can use the simple formula to work it out in metric or imperial.
My portable setup
Below are some videos on my portable setup which you may enjoy.
If you enjoyed this read, below are some you may also enjoy.
- Dipole Antenna for Portable Use – Make your own!
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VK3TBS 