Active Heatsink Antenna for Radio-Frequency Transmitter

This paper deals with the design of an active heat-sink antenna for radio-frequency transmitter. The antenna achieves electromagnetic and thermal functions by offering a suitable radiating pattern for transmission as high efficiency to remove the dissipated power within the transmitter by heat exchange to the surrounding medium. A test transmitter has been performed by combining a 2 GHz MESFET power amplifier in a conductor-backed coplanar wave-guide with a wire-fed patch heat-sink antenna connected to the ground plane. The active heat-sink antenna has been investigated by measurement and simulation. As expected, it was found that the antenna exhibits desirable electromagnetic performance as achieving an efficient thermal control by offering suitable operating temperature. A heat spreader connecting the transistor to the antenna, was especially developed to cause any significant influence on transmitter performance. The amplifier can deliver an output power as high as 5 W under natural convection with air at room temperature and atmospheric pressure. According to the temperature and direction of the antenna, thermal resistance of the transmitter was found between 6 and 8 K.W ^-1. The transmitter can thus operate over a wide temperature range without any additional cooling device.