SWRS045F January 2006 – November 2018 CC1021
PRODUCTION DATA.
The CC1021 device can be used together with various types of antennas. The most common antennas for short-range communication are monopole, helical and loop antennas.
Monopole antennas are resonant antennas with a length corresponding to one quarter of the electrical wavelength (). They are very easy to design and can be implemented simply as a “piece of wire” or even integrated onto the PCB.
Non-resonant monopole antennas shorter than can also be used, but at the expense of range. In size and cost critical applications such an antenna may very well be integrated onto the PCB.
Helical antennas can be thought of as a combination of a monopole and a loop antenna. They are a good compromise in size critical applications. But helical antennas tend to be more difficult to optimize than the simple monopole.
Loop antennas are easy to integrate into the PCB, but are less effective due to difficult impedance matching because of their very low radiation resistance.
For low-power applications, the monopole antenna is recommended due to its simplicity as well as providing the best range.
The length of the monopole antenna is given by:
Where: f is in MHz, giving the length in cm.
An antenna for 868 MHz should be 8.2 cm, and 16.4 cm for 433 MHz.
The antenna should be connected as close as possible to the IC. If the antenna is located away from the input pin the antenna should be matched to the feeding transmission line (50 Ω).