A Folded Dipole PCB Antenna Design

This application note describes the design of a folded dipole antenna for CC2400, CC2420, CC2430 and CC2431. The CC2400 is a true single-chip, general-purpose transceiver for the 2.4 GHz SRD band for data rates up to 1 Mbps. The CC2420 is a true single-chip RF transceiver designed for low power wireless networks operating in the 2.4 GHz SRD band compliant to the ZigBee™/IEEE 802.15.4 standards. CC2430 is a true SOC combining the CC2420 with a single cycle 8051 microcontroller. CC2431 is CC2430 with location engine.

The design described in this application note is based on the CC2400, but it can be used for CC2420, CC2430 and CC2431 as they have the same RF front end. The RF front end consists of three pin connections. Two pins serve as a differential interface shared by the LNA and PA. The third pin changes voltage level in order to provide power to the PA during transmission and ground to the LNA during reception. A differential interface provides a better utilisation of the available supply voltage as well as less parasitic capacitance to ground.

Design criteria for the antenna and the design process are described. Also included are test results and a comparison of the tested antenna to a balun and monopole antenna solution.