In this thesis, we investigate the design and fabrication of a conical spiral antenna suitable for the satellite TT&C applications. The shape of the spiral is optimized using a commercial electromagnetic software for good gain and axial ratio performances at 2.0-2.3 GHz. The coaxial infinite balun feeding the spiral is designed using experimental methods. A method for precision fabrication of the spiral is presented. Measurements of the fabricated antenna shows satisfactory performances at 2.0-2.3 GHz such as the reflection coefficient less than -18 dB, the gain greater than 4 dB, the gain greater than 0 dB over angles ±75˚ from the antenna boresight, the axial ratio less than 5 dB over angles ±90˚ from the antenna boresight, the front-back ratio greater than 15 dB.