The product example has an integrated chip antenna from Johanson Technology.
Go to Johanson Technology for more information on the chip antenna. The antenna is tuned to be resonant at 2.44 GHz, and the impedance is matched to the 50 Ω output of the balun with the use of two series inductors (L1 = 3.3 nH, L2 = 1.5 nH) and a shunt capacitor to ground (C4 = 1.2 pF). The antenna in this design is tuned for this layout only, and with the same plastic casing. If the layout and/or the casing is changed, it is likely the antenna must be retuned. The antenna can be retuned by adjusting the values of L1, L2 and C4. The exact values of the components must be determined by measurements with a vector network analyzer.
Figure 1. Matching network and antenna circuit
