Short and open circuit in radio frequency
You should study why open-ended and closed-ended pipes resonate: -



Picture from here

It's the same mechanism as an electrical stub (open or short).

So, in the top example the closed-end pipe will resonate when the applied frequency is such that the length (L) is a quarter wavelength of the frequency. When the pipe is resonant it acts like a parallel resonant tuned circuit and offers a high impedance to the applied frequency. This is the shorted quarter wave stub.

In the lower example, the pipe is open-ended and, to produce a parallel resonance (high impedance) requires a pipe length (L) twice as long.

This is an open half wave stub and is resonant exactly the same as a shorted quarter wave stub but requires twice the length.

If a quarter wave stub is open circuit it behaves like a series resonant tuned circuit and this produces an impedance of zero ohms at resonance. Horses for courses.


  1) Does this RF short circuit have the same meaning as our normal
  short-ciruit i.e. very high current flowing?


Yes it has the same meaning but only at the precise frequency where it becomes a short.


  2) What is the physics or reasoning that I can produce a short circuit
  with a DC-open?


Well, the pipe analogy above should help you understand that. Here's more of an electrical picture: -



Picture from here.