Design of a slot-coupled quarter wavelength microstrip pocket antenna at 430 MHz for a hand-held measurement instrument

We describe the experimental design of a slot-coupled microstrip pocket antenna for a hand-held measurement instrument. We also include measured results for the reception quality. The San-Eisha company manufactures a hand held device for measuring the phases of high voltage distribution networks within cities, in order to enable correct connection to electrical equipment. The measurements are done simultaneously at two locations separated by up to a few hundred meters. The quality of the measurements depends on reliable communication between the two operators. Therefore, the hand-held instrument is provided with a microwave communication system operating at 429.5 MHz with a narrow /spl plusmn/0.5 MHz bandwidth and a transmitter power of 10 mW. The previous antenna was an inverted F type of design located inside a box together with other electronic components. The box has plastic walls and is integrated with the rest of the hand-held instrument. The previous antenna was expensive to install as each sample needed tuning of the center frequency. Also, it was strongly effected by the other electronic components in the box. The authors present the design a new antenna with better characteristics.