Consider the following statements about the smith chart:

1. A complete revolution (360°) around the Smith that represent a distance of half wavelength on the line.

2. Clockwise movement on the chart is regarded as moving toward the generator.

3. Although three scales around the periphery of Smith chart are used, but only one scale can be sufficent.

4. Smith chart cannot be used as admittance chart.

Which of these statements are correct?

Concept:

Properties of smith chart:

i. One complete revolution (360^o) around the smith chart represents a distance of λ/2 online or λ → 720^o. 

ii. Clockwise movement represent ⇒ Towards generator or (away from the load)

iii. Counterclockwise movement ⇒ Towards the load.

iv. V_max occur where Z_{in max} located i.e. at P_oc (0^o)

V_min occur where Z_{in min} located i.e. at P_sc (±180^o)

v. V_max and V_min are λ/4 (180^o) apart.

vi. Smith chart is used both impedance and admittance chart.
 

The outermost scale is used to determine distances in wavelengths toward the generator and the next scale is used to determine distances in wavelengths toward the load.

The innermost scale is a protractor (in degrees) and is primarily used to determine the phase of the reflection coefficient and the phase of the transmission coefficient.
 

Calculation:

Statement 1, 2, 3 are correct

Smith Chart is also used as an admittance chart so statement 4 wrong.

hence the correct choice is an option (d) 1, 2, 3 only.

∵ 2Bl = 2π              (One complete revolution)

\(2 \times \frac{{2\pi }}{\lambda } \times \ell = 2\pi \)

\(\left(\because{\beta = \frac{{2\pi }}{\lambda }} \right)\)

\(\ell = \frac{\lambda }{2}\) ⇒ so one complete revolution is \(\frac{\lambda }{2}\) distance.