Microwave Polarization: Understanding Light and Wave Properties

Posted on Jan 28, 2025 in Electromechanical Engineering

Objectives:

  • To study the phenomenon of polarization in a beam of light, using a microwave as a polarizer to alter the polarization generated by a radiation source.

Planning:

Electromagnetic waves, such as light or microwaves, are characterized by the vibration of electric (E) and magnetic (B) fields. These fields are transverse to each other and perpendicular to the direction of propagation. The speed of wave propagation matches the speed of light, which is C = 3×108 m/s (Hecht).

When an unpolarized light beam is incident on a polarizing foil with a vertical polarization axis, the light passing through this layer is polarized in the direction of the polarization axis. If we put a second polarizing sheet, which we call an analyzer, it intercepts this light beam and switches from the first sheet as a function of the angle affixed to the polarization axis with the first sheet’s polarization axis. The transmitted intensity has its maximum when the polarization axes are parallel and zero when the axes are perpendicular, according to Malus’s Law.

Procedure:

Part 1: Light Intensity

Conduct a search of the light intensity by manually rotating the second polarizing sheet. Graph intensity versus the angle of rotation.

  1. Set up two charts for recording information (intensity on the vertical axis).
  2. Assign the instance and angular position of the abscissa.
  3. Set the following equations, one in each graph: y = z * cos(x) and y = z * cos2(x)
  4. Define the variables z = intensity of light, x = angular position, equations on the menu, and click OK.

As Figure 1 (luminous intensity-channel A-channel angular position vs. 1 and 2) is equal to graph 3 (y2-can vs. angular position ales 1 and 2), we deduce that we are seeing strength.

  1. Compare the graphs that were obtained: 1) Intensity vs. angular position, 2) Intensity * cos(angular position), 3) Intensity * cos2(angular position).

Part 2: Microwave Polarization

  1. Note the reception when the polarizer is aligned at 0°, 25°, 45°, 75°, and 90° with respect to the horizontal. Complete Table 7-2.
  2. Remove the polarizer and rotate the receiver 90° in relation to the transmitter. Note the value of the measurement.
  3. Place the polarizer again in vertical, horizontal, and 45° positions and note the values received.

Angle of Polarizer | Meter Reading (mA)

0° (Horiz.) | 0.92

25° | 0.7

45° | 0.3

75° | 0

90° (Vert) | 0

Angle of Slits | Meter Reading (mA)

Without Polarizer | 0

Horizontal | 0

Vertical | 0

45° | 0.3

Frequently Asked Questions

2. If the receiver measures the field, will the Radio Spectrum Committee (1) and (2) be similar?

If it measures the intensity of the electromagnetic wave, the results will be similar to (1) and (3). Since graphs (1) and (3) are similar, (1) and (2) are not listed.

3. Determine what the receiver used measures.

It measures the current intensity (mA) of microwave radiation generated by the diode located on the transmitter.

4. Based on the results of the microwave part, explain how the polarizer affects the incident microwave.

The change in the angle of the polarizer (with the receiver at 0°) produces the same effect on the incident wave.

5. Explain the results in Table 7-3.

Varying the angle by 90 degrees, plus the receiver, summarizes the previous two tables.