Antenna Lab Report 5

Determine the effect of polarization on antenna: The hardware was setup as shown in the lab manual for this task. After setting the apparatus the radiation pattern of the antenna was observed by varying the position of transmitter and receiver in horizontal and vertical position. The polarization provides information about the radiating electric field of electromagnetic wave in far field.

The figure of 8 was formed when both antennas are horizontal. It shows that maximum signal is received. When the antenna is held vertical then the graph obtained is shown in the figure below.

When both transmitter and receiver are held vertical, the outer circle type graph was obtained with good received signal strength that can be seen in above graph. This is due to same polarization pattern at receiver and incoming signal. When yogi antennae were held horizontal

with dipole antenna in horizontal position, the inner graph was obtained with significantly less strength due to opposite polarization of antenna.

Describe an antenna in NEC-Win and investigate its beam width in free space: In this task, dipole antennas of different sizes were modeled simulated and their radiation pattern was observed in 2D and 3D as well. Moreover, azimuth and elevation plots were also created for perfect conductor with 10 awg dia with dipole along y-axis at 1500 MHz frequency. Graph at left is azimuth plot of the given specifications below while graph at right is elevation plot of the modeled antenna.

For L< 1/2λ at f = 1500 MHz:

For L ~ 1/2 λ at f = 1500 MHz:

For L ~ λ at f = 1500 MHz:

Observations: a) Yes it has same response in all directions as the elevation plot is a circle. b) Response is maximum in 0 and 180. c) Response is minimum in the direction of 90 and 270. d) Yes, we see that the surface plot is like a figure of ‘8’ in azimuthal plane and circle in elevation plane. e) Yes the dipole was mounted on the generator tower being operated in free space. f) For l< λ/4 beam width=84 degrees, for l< λ/2 beam width=75 degrees, for l< λ beam width=51 degrees.