why only shunt Component is required for PCB Antenna Tuning

[SaiTeja]

Below linked blogpost says, if using a PCB antenna, the matching network should consist of one shunt component. devzone.nordicsemi.com/.../ . And in the reference design 1.2 pF is used. So I am assuming shunt capacitor is need to be added for tuning PCB antenna.

If my assumption is correct, the real value of admittance of PCB antenna should always be 0.02 mho to match impedence to 50 ohm. How can the admittance of any PCB antenna can always be 0.02 ohm? Where am I thinking wrong?Why only one shunt component is sufficient for tuning PCB antenna? For antenna tuning procedure, I referred below linked white paper. infocenter.nordicsemi.com/.../nwp_017.pdf

[AmbystomaLabs]

Other antenna designs, such as a PIFA, have matching as part of their design. So on a PIFA the F bit shorts to ground to match the antenna. In this manner other antenna designs can give close to 50 ohm performance without external discrete matching components.

Always do your antenna characterization in the final product housing/mounting arrangement. Plastic, screws, hands, walls will all severely change the tuning of the antenna.