I am looking to dabble into some RF PCB design with a microstrip line to a WiFi chip antenna, and I am trying to understand if my intuition is correct.
I have used various calculators to determine the width of the trace I need for a 50\$\Omega\$ \$Z_0\$ on a 4 layer PCB -- all agree with roughly 18 mils on FR4.
Since the transmitter, transmission line, and chip antenna are all 50\$\Omega\$, there should be no standing wave pattern along the line and \$V(x)\$ and \$I(x)\$ (where \$x\$ is the position on the line) should be constant.
Aside from ohmic losses and parasitics (which the latter can be tuned out), does this imply that the length of the line can be arbitrary? i.e., the trace does not need to be a specific electrical length such as \$\lambda/4\$?
I am leaning towards that it isn't, but I've reviewed some reference designs from TI (the CC3100BOOST and the CC3200 Launchpad) that have caused some confusion. The CC3100 uses a trace length of 660mil from chip to antenna, which is almost exactly \$\lambda/4\$ at 2.4GHz, and the CC3200 uses a 1200 mil line, which is very close to \$\lambda/2\$. I'm not sure if this is intentional or a coincidence.
I'm looking for a (perhaps tediously) clear answer before I make any mistakes.