EXPERIMENT 1

MEASUREMENT OF FREE SPACE WAVELENGTH AND GUIDE WAVELENGTH

Aim: To determine the Free Space Wavelength and Guide Wavelength using a microwave trainer.

Objective:

To measure guide wavelength & frequency of a signal in a rectangular wave guide.

To understand the relationship between the wave guide and the free space

To analysis the effect of increase or decrease the operating frequency on the wave guides.

Equipment and Components required:

Gunn Power Supply.

Square wave Oscillator.

Gunn Oscillator.

PiN Modulator.

Variable Attenuator.

Frequency Meter.

Slotted line with detector probe.

Wave guide section.

Display Unit (CRO).

Reflecting plate Short.

Experimental Set-up:

4178398295910CRO

00CRO

-351790212090Power Supply

00Power Supply

746125197485Square wave Oscillator

00Square wave Oscillator

4615034133985115379513335-952510795

6515100153719005276215181610Wave guide section

00Wave guide section

4175760226695Slotted line

00Slotted line

3051810215265Frequency Meter

00Frequency Meter

1891030182245Variable Attenuator

00Variable Attenuator

746760180975PiN Modulator

00PiN Modulator

-405765143510Gunn Oscillator

00Gunn Oscillator

50457101885950039185852425700027585382422770046482018986500164147522542500

63744232634270

614489512446000

Reflecting plate

Procedure:

Connect the Pin wire modulator from the device to the CRO to apply 1 KHz, and 2 p-p. make the variable attenuator equal 10 dB.

Turn on the Gunn power supply, change voltage from power supply to be appropriate full scale (p-p). Make the frequency oscillation equal to 9GHz.

Set the Gunn power supply and show a clear square wave in the power supply on the CRO.

Move the frequency meter until there is drop in the signal level. Record the reading that show from the frequency meter in the table.

Start measure the wavelength; put the reflecting plate perpendicular to the waveguide.

Move the reflecting plate, the CRO shows the first minimum and second minimum waves and measure the distance by the ruler.

Close the wave guide by the shorting plate and measure the distance between two adjacent NULL by the slotted line.

Observation:

Measured Frequency (GHz) Calculated frequency (GHz) Measured ?o ?o = 2(d2 – d1) (cm) Calculated ?o (cm) Measured ?g ?g = 2(dS2 – dS1) (cm) Calculated ?g (cm)

11.260 GHz 11.26 GHz d1=1.6 cm

d2=2.9 cm

?o=2.6 cm ds1 = 0.4 cm

ds2 =2 cm

?g =3.2cm -3

26.642× 10 m -3

32.827×10 m

Skill Drill:

Change the operating frequency and analyze the effect in the wavelength.

Measured Frequency (GHz) Calculated frequency (GHz) Measured ?o ?o = 2(d2 – d1) (cm) Calculated ?o (cm) Measured ?g ?g = 2(dS2 – dS1) (cm) Calculated ?g (cm)

10.34 GHz 9 GHz d1=0.6 cm

d2=2 cm

?o=2.8 cm ds1 = 0.8 cm

ds2 =1.3 cm

?g =1 cm -3

29× 10 m -3

48.75 × 10 m

Result & Analysis:

Measured the free and find the distance of two minimum waves. Calculated the ?o by the formula of the two distances, values range from 0.4 n 3.2 cm .Than calculated the ?g by given formula. Next change the operating frequency to analyze the effect in the wavelength. Measured Frequency equal to 10.34 GHz and the calculated frequency equal to 9GHz. Repeat the same step to calculate the ?o and ?g by the given formula the values range from 0.6 and 2.8 . Those values shows the effect of the frequency on the wavelength where a larger frequency means a smaller wavelength.

Discussion & Conclusion:

In conclusion, understand the microwave trainer uses. Also how to measure the distance of the wave length of free space and getting the minimum waves. Than measure the minimum wave length of the wave guides by the slotted line and calculate the distance. After that analyze the effect of the frequency on the wavelength which is increasing the frequency means decreases on the wavelength. We use it in the applications of our daily lives without knowing how its work. Use it in microwave communications, broadcasting, and radar installations.