Experiment No. 1

Study of Antenna Polarization, Axial Ratio and Tilt Angle of a circularly polarized antenna.

Scope of study:

In this experiment, the student will measure the axial angle of a circularly polarized antenna.

Procedure:

Mount the horn antenna on the turn table with E field in vertical plane and connect it with the receiver through a coaxial cable.

Mount helical antenna on the antenna mount and connect it with the transmitter through a coaxial cable. The Helical antenna will act as transmitting antenna.

Set distance between the transmitting helical antenna and receiving horn antenna such that both are in far field zone. This can be done by calculating the far field range which is equal to (2D^2)/λ where D is the maximum dimension of the antenna (in the case of the helical antenna it is equal to the length of helix).

D = ___________________ λ = _____________________

Minimum distance between Tx and Rx “(2D^2)/λ” = _____________

Align both antennas both facing towards each other. Switch on transmitter and receiver. The receiver will display level of received signal in mVs. Readjust alignment of the antenna till you get maximum signal in the receiver.

Next rotate the horn antenna till the received signal in the receiver is, maximum. Record the results as below:

Meter reading in (mVs) = ________________________

Received power “Pmax” dBm = ___________________

Next rotate the horn antenna till the received signal in the receiver is, minimum. Record the results as below:

Meter reading in (mVs) = ________________________

Received power “Pmax” dBm = ___________________

The axial ratio “AR” is then given by:

Axial ratio = Antilog (Pmax – Pmin / 20)

AR = ____________________________

Experiment No. 2

Study of Dipole Antenna and its Radiation Pattern

Scope of study:

In this experiment, the student will measure the E and H planes radiation patterns of a dipole antenna.

Procedure:

Mount the dipole antenna with E field in vertical plane on the turn table and connect dipole antenna port with the receiver through a coaxial cable.

Mount horn antenna with E field in vertical plane and connect it to the transmitter through a coaxial cable. The Horn antenna will act as transmitting antenna.

Set distance between the transmitting antenna and dipole antenna such that both are in far field zone. This can be done by calculating the far field range which is equal to (2D^2)/λ where D is the maximum dimension of the antenna (in the case of the dipole antenna it is equal to the dipole length).

D = ___________________ λ = _____________________

Minimum distance between Tx and Rx “(2D^2)/λ” = _____________

Align both antennas both facing towards each other. Switch on transmitter and receiver. Readjust alignment of the antenna till you get maximum signal in the receiver. The receiver will display level of received signal in (mV) from the digital display and convert it into power using the calibration graph. Record the results as below:

Maximum received signal power “PRmax” = ______________ dBm

Next rotate base of turntable till it reads 0 deg without distributing the position of the dipole antenna. Turn dipole in step of “5” degrees, in both clockwise and counter clockwise direct ions. For each setting note the corresponding level of the received signal and record the results as below:

θ degree CW

Level dBm Relative Power (dB)

θ degree CCW

Level dBm Relative Power (dB)

0 05 -510 -1015 -1520 -2025 -2530 -3035 -3540 -4045 -4550 -5055 -5560 -6065 -6570 -7075 -7580 -8085 -8590 -90

Plot the radiation pattern on polar. The radiation plot will be E plane plot of dipole. Measure -3dB beam with form the plot and record the results below:

-3bd Beam width of the dipole antenna in E plane = _______________ degrees

Rotate the dipole and horn antenna by 90 degrees and repeat above step. Record the results bellows:

φ degree CW

Level dBm Relative Power (dB)

φ degree CCW

Level dBm Relative Power (dB)

0 05 -510 -1015 -1520 -2025 -2530 -3035 -3540 -4045 -4550 -5055 -5560 -6065 -6570 -7075 -7580 -8085 -8590 -90

Plot the radiation pattern on polar. The radiation plot will be H plane plot of dipole. Measure -3dB beam with form the plot and record the results below:

-3bd Beam width of the dipole antenna in H plane = _______________ degrees

Experiment No. 3

Study of Pyramidal Horn Antenna

Scope of study:

In this experiment, the student will measure the E and H planes radiation patterns of a pyramidal horn antenna.

Procedure:

Physical measure the aperture of the pyramidal horn and record the readings as below:

a1 = __________ cm b1 = ___________ cm

The gain of the horn is given by:g = a1 x b1 x 6.4/ λ^2 G dB = 10 log (g)

G dB = ___________

Align th transmitting antenna with the horn. Set distance between them such both are in far field zone. This can be done by calculating the far field range which is equal to (2D^2)/λ where D is the maximum dimension of the antenna (in the case of the D is equal to the Diagonal dimension of horn aperture).

D = ______________ cm λ = _______________cm

Minimum distance between Tx and Rx “(2D^2)/λ” = _____________cm

Align both antennas both facing towards each other. Switch on transmitter and receiver. Readjust alignment of the antenna till you get maximum signal in the receiver. The receiver will display level of received signal in (mV) from the digital display and convert it into power using the calibration graph. Record the results as below:

Maximum received signal power “PRmax” = ______________ dBm

Next rotate base of turntable till it reads 0 deg without distributing the position of the dipole antenna. Turn dipole in step of “5” degrees, in both clockwise and counter clockwise directions. For each setting note the corresponding level of the received signal and record the results as below:

θ degree CW

Level dBm Relative Power (dB)

θ degree CCW

Level dBm Relative Power (dB)

0 05 -510 -1015 -1520 -2025 -2530 -3035 -3540 -4045 -4550 -5055 -5560 -6065 -6570 -7075 -7580 -8085 -8590 -90

Plot the radiation pattern on polar. The radiation plot will be E plane plot of dipole. Measure -3dB beam with form the plot and record the results below:

-3bd Beam width of the dipole antenna in E plane = _______________ degrees

Rotate the dipole and horn antenna by 90 degrees and repeat above step. Record the results bellows:

φ degree CW

Level dBm Relative Power (dB)

φ degree CCW

Level dBm Relative Power (dB)

0 05 -510 -1015 -1520 -2025 -2530 -3035 -3540 -4045 -4550 -5055 -5560 -6065 -6570 -7075 -7580 -8085 -8590 -90

Plot the radiation pattern on polar. The radiation plot will be H plane plot of dipole. Measure -3dB beam with form the plot and record the results below:

-3bd Beam width of the dipole antenna in H plane = _______________ degrees

Experiment No. 4

Measurement of the gain of Horn antenna using method of two Antennas

Scope of study:

In this experiment, the student will learn how to measure gain of horn antenna.

Procedure:

Measurement of Transmitter RF Power:

Connect coaxial cables to the transmitter and the receiver. Now interconnect Tx and Rx through a coaxial attenuator of 20 dB.

Switch on the Tx and Rx.

Using the calibration curve, translate reading of the Rx display to received power and record the result below:

Pr = ______________ dBm

The transmitter RF power is given by:

Pt dBm = Pr dBm + 20 dBm

Pt = ______________ dBm

Remove the attenuator. Connect transmitter with the Horn antenna and mount it on the stand. Connect receiver with the Horn antenna and mounted it in the receiver’s stand.

Align the transmitting antenna with E field in vertical plane and set the distance between the transmitting horn and receiving Horn antenna such that both are in far field zone.

Rmin = (2 D^2)/ λ = _________________ cm

Vary distance between two horn antennas and note down the reading of the receiver and translate received power in dBm. On each distance setting align the antenna for maximum received power. Using equation 1, calculate antenna gain G. Take at least three readings and record the result below:

Distance between the antennas “R”

Received Power Pr in dBm

Gain of Horn antenna G in dB

Mean Gain of the horn antenna = ___________________________ dB

Experiment No. 5

Study of Yagi-Uda Antenna

Scope of study:

In this experiment, the student will observe the radiation pattern of a Yagi-Uda antenna.

Procedure:

Measurement of Transmitter RF Power:

Mount the Yagi antenna with E field in vertical plane on the turn table and connect the it’s antenna port with the receiver through a coaxial cable.

Align the transmitting antenna with E field in vertical plane and set the distance between the transmitting horn and Yagi antenna such that both are in far field zone.

Switch on transmitter and receiver. Set receiver gain till you get of the meter deflection with in its scale. Readjust alignment of the antenna till you get maximum signal in the receiver.

Next rotate base of turntable till it reads 0 deg without distributing the position of the Yagi antenna. Turn Yagi in step of “5” degrees, in both clockwise and counter clockwise directions. For each setting note the corresponding level of the received signal and record the results as below:

θ degree CW

Level dBm Relative Power (dB)

θ degree CCW

Level dBm Relative Power (dB)

0 05 -510 -1015 -1520 -2025 -2530 -3035 -3540 -4045 -4550 -5055 -5560 -6065 -6570 -7075 -7580 -8085 -8590 -90

Plot the radiation pattern on polar. The radiation plot will be E plane plot of Yagi. Measure -3dB beam with form the plot and record the results below:

-3bd Beam width Yagi antenna in E plane = _______________ degrees

Rotate the Yagi antenna and transmitting antenna by 90 degrees and repeat above step. Record the results bellows:

φ degree CW

Level dBm Relative Power (dB)

φ degree CCW

Level dBm Relative Power (dB)

0 05 -510 -1015 -1520 -2025 -2530 -3035 -3540 -4045 -4550 -5055 -5560 -6065 -6570 -7075 -7580 -8085 -8590 -90

Plot the radiation pattern on polar. The radiation plot will be H plane plot of Yagi antenna. Measure -3dB beam with form the plot and record the results below:

-3bd Beam width of the Yagi antenna in H plane = _______________ degrees