Consider the following statements regarding the load matching and impedance measurements:
1. A mismatched load can be properly matched to a line by inserting prior to the load a transmission line $$\frac{\lambda }{4}$$ long.
2. For matching of 120 Ω load to a 75 Ω line, the quarter-wave transformer must have a characteristic impedance of 190 Ω.
3. The main disadvantage of single-stub matching is that it is a narrow-band or frequency-sensitive device.
Which of the above statements are not correct?