This is a kind of job I do several times each day. In most cases is it wide band or multi band matching.
What procedure and how to calibrate is a bit depending on if 50 Ohm is a requirement.
For embedded antennas is 50 Ohm as impedance seldom an optimal goal.
Assume VNA and its main cable is calibrated reasonably well.
As standard do I then add a thinner coaxial pigtail, ~100mm. One end with SMA and other end is soldered at point F.
Near F, direction antenna, is CU trace cut.
F is shortcut with an exacto to ground
Then do I set auto port forwarding and auto impedance calibration in a special PC software, special designed for this kind of job, AnTune. It reads data from VNA over LAN/USB/GPIB.
It do then compensate for time delay and impedance losses. Time delay is caused by added cable length, 100 mm, and also these few mm CU traces and pad between cable connection point and pad of point F have added.
Impedance losses are due to non ideal 50 Ohm cable in this 100 mm cable and CU-trace. Even size of PAD and internal PCB ground losses can affect tuning result if not proper handled.
Next, in AnTune select type of matching components, so that these non ideal behavior can be auto compensated for. Also slect preferred topology or let AnTune select optimal alternative.
Then can an actual measurement be performed. This is done by shortcut to point D. Trace in antenna direction is since previous cut. activate radio and measure TX and RX impedance. Save these curves in AnTune.
Be careful to not overload VNA if TX power is above what VNA can handle, typical is power up to 20dBm not any problem, for higher power must attenuation be added, before calibration of main cable.
If it exist additional TIS or TRP requirement, add them in AnTune.
Set resulting curve in AnTune as reference impedance. AnTune will use its conjugate for antenna impedance matching.
Now remove shortcut between D and F and repair the cutted trace against antenna with a small wire or solder blob.
Now is antenna impedance measured and in AnTune can it be directly read what component values should be used for the selected topology and type of component family.
Solder these three components in place and then confirm that Tx/Rx impedance now is a perfect wideband conjugate match of antenna impedance by once again remove solder blob against antenna.
At high frequencies, ++2GHz, and if it is measurable losses and delays between each matching component, do this last confirmation fail or is not good enough. In these cases, depending on situation but then is just the component at F soldered in place and measurement cable is moved just behind E and procedure is repeated, measuring antenna impedance and component F, to find optimal value for E, and finally component D.
Above procedure do maybe seem complicated, but it do never take more then a few minutes and final matching result can never be an surprise. Trace reactive loss and delay between D and actual radio is then not a problem. Radio internal impedance becomes optimal loaded even if it not is 50 Ohm, which it never is even if data sheet says so.
A big advantage is that AnTune requires almost no settings except selecting components, topology and frequency, and have a learning curve around two minutes.
AnTune calculates optimized matching network live. Result is presented at PC screen as fast as it can be delivered from VNA. That makes tuning directly at antenna very easy as final matched result can be seen while adjusting antenna shape. No else software is able to do this.
My opinions about AnTune is very biased as I am the developer of the extremely fast matching algorithm.
AnTune was developed by me with the only goal, to make embedded wide band antenna design with highest possible efficiency and optimized matching network design as fast and simple as possible. Both these, best matching and best efficiency are depending on each other so that is why I prefer above described procedure, which includes measuring both radio and antenna impedance and include internal PCB traces in these measurements. Traces are maybe short and with an ideal impedance close to radio impedance. Radio impedance is maybe very close to data sheet numbers . It have just not happen for me yet.
Another important thing is that when a optimized network is decided can AnTune save a document including all relevant curves and BOM with art.no for actual tuning components.
That is important as especially inductors of different types and brands, even if same inductive value, can have very different behavior at higher frequencies.