Lab 7

Microwave Optics

Bill Chun Wai Hung

Marjan Montakhab

Nimish Kumar

Friday Section

26 May 2004

Data and Calculation:

1. Klystron Operation

+B Voltage = 300V

-C Voltage = 100V

Beam Current = 17mA

Maximum Receptor Voltage = 137.227mV

Output Voltage for +B = 300V

Output Voltage for –C = 49V

2. Polarization

Table 1.

	Orientation	Voltage(mV)	% Relative to the Orginal Voltage (%)
1	Original Voltage	137.227	100.0
2	One Horizontal Grid	98.413	71.7
3	One Vertical Grid	7.788	5.7
4	Two Horizontal Grid	72.609	52.9
5	Horizonal and Vertical Grid	2.854	2.1
6	Two Vertical Grid	2.097	1.5
7	Vertical Receptor	2.183	1.6
8	45 Degrees Grid	29.054	21.2

3. Standing Wave

Distance of Maximum Intensity (cm)

6.2

7.9

10.1

12.0

Avg Length = Wavelength = 2.1cm

Frequency (= c/wavelength) is 1.43 x 10¹⁰Hz.

4. Frequency Variation

Wavelength 1

Distance of Maximum Intensity (cm)

6.3

7.6

9.2

10.8

Wavelength = 2.175cm

Frequency = 1.38 x 10¹⁰Hz

Wavelength 2

Distance of Maximum Intensity (cm)

6.1

7.2

8.3

9.4

Wavelength = 1.65cm

Frequency = 1.82 x 10¹⁰Hz

Conclusion by Bill Chun Wai Hung:

1. Klystron Operation

After setting up the equipments according to the procedure, the voltage for +B is 300V, and the voltage for –C is 100V. The beam current is 17mA.

When the –C voltage is adjusted between 100V and 200V, the maximum receptor voltage was found to be 137.227mV. At the maximum receptor voltage, the Output Voltage for +B is 300V, and the output voltage for –C is 49 V.

Q: How does the intensity vary with distance from the output horn?

By moving the detector horn from side to side (perpendicular to the direction of the transmitter horn), the farther the detector horn from the original axis, the lower the intensity of the radiation received (lower voltage detected).

By moving the detector horn away from (parallel to the direction of the transmitter horn) the transmitter horn, the intensity goes up and down (like a sine wave) while the maximum intensity generally goes down.

Graph:

2. Polarization

When there are no metal grids, the receptor voltage is 137.227mV, this is referred to as the original voltage, 100%. The percentages below are relative to this original voltage.

Graph:

1.
When one metal grid is placed horizontally between the transmitter and the receptor, the receptor voltage is 98.413mV, or 96.6%

2.
When on metal grid is placed vertically between the transmitter and the receptor, the receptor voltage is 7.798mV, or 5.7%.

3.
When on metal grid is placed horizontally and the other also placed horizontally between the transmitter and the receptor, the receptor voltage is 72.609mV, or 52.9%.

4.
When on metal grid is placed horizontally and the other placed vertically between the transmitter and the receptor, the receptor voltage is 2.854mV, or 2.1%.

5.
When on metal grid is placed vertically and the other also placed vertically between the transmitter and the receptor, the receptor voltage is 2.097mV, or 1.5%.

6.
When one metal grid is placed horizontally and the other also placed horizontally between the transmitter and the receptor, the receptor voltage is 72.609mV, or 52.9%.

7.
When the receptor horn itself was 90 degrees from it’s originally horizontal position, the receptor voltage is 2.183mV, or 1.6%.

8.
When a metal grid is placed 45 degrees to the horizontal, the receptor voltage is 2.905mV. The reading is 13.6 times the Voltage in #7 (2.183mV), and is 21.2% of the original voltage.

This part of the experiment shows that the wave generated from the transmitter is polarized because different orientation of the grids and the horns gives different intensity of the signal. The 45 degree metal grid improved the signal reception by blocking the vertical component of the wave, and allowing the horizontal component of the wave to pass through. This polarized the wave by 45 degrees, and improved the signal reception.

The results of this part of the experiment is summarized in Table 1

3. Standing Wave

Distance of Maximum Intensity (cm)

6.2

7.9

10.1

12.0

The average distance for the maximum intensity of the wave is found to be 2.1cm, which means the wavelength of the wave is 0.021m, and the frequency (= c/wavelength) is 1.43 x 10¹⁰Hz.

4. Frequency Variation

By turning the screw of the transmitter horn, a maximum and minimum wavelength of the wave were recorded as 2.175cm and 1.65 cm respectively, and the frequency were 1.38 x 10¹⁰Hz and 1.82 x 10¹⁰Hz respectively.