How do I make my own FM transmitter?

Fm Transmitter Aerial, I need to make an fm transmitter aerial for 99.90 mhz,?

• my transmitter is 20 watts, ive had a look through the web and was wondering if the aerial would need some sort of "short circuit / closed circuit" to function? ive seen the bipole antenna diagrams but some show some sort of "short" before the lengh of the copper for desired frequency and others dont show this. i really dont want to damage the transmitter doing this... i am an electrician so got most tools at the ready but not sure about this "short circuit" or not. any help will be mostly appreciated and thanks for reading this

• Answer:

  No, there is no short circuit. You need to run a coaxial cable (preferably 50 ohm impedance) from the transmitter to the antenna. You can either use a bipole antenna, with the coaxial shield connected to one pole and the core of the coax connected to the other pole. The length of each pole of the dipole is 0.75m (the full wavelength at 99.9MHz is 3m). OR, you can use a ground plane, which is a sheet of metal, at least one square metre to which the shield of the coax is connected and a metal rod of length 0.75m which is insulated from the ground plane, but projects at 90 deg from the ground plane, to which the core of the coaxial cable is connected. The ground plane solution is good for vertical polarisation, whereas the dipole can be oriented either vertically or horizontally, just make sure that the receiving antenna is oriented the same way as the transmitter.