Objective:

Material and Equipment Required:

Experiment Observation:

In this experiment, we observed the radiation pattern of two types of antenna. At the beginning of the experiment, we used Yagi-Uda antenna as the receiving antenna.  We observed the radiation pattern of E-plane for Yagi-Uda (refer to Figure 1). Next, we obtained the radiation pattern of H-plane for Yagi-Uda (refer to Figure 2).  After these two acquisitions, we able to observe the combination radiation pattern of E- and H- planes for Yagi-Uda in 2-dimesion (refer to Figure 3) and in 3-dimension (refer to Figure 4).  We found that the half power beam width (HPBW) and directivity for Yagi-Uda are as below:
• HPBW (E plane) = 40 Degrees
• HPBW (H plane) = 45 Degrees
• Directivity = 13.1dB

Next, we repeated the experiment with half-wave dipole as receiving antenna.  The radiation pattern that we observed were E-plane (refer to Figure 5), H-plane (refer to Figure 6), combination radiation pattern of E- and H- planes in 2-dimesion (refer to Figure 7) and in 3-dimension (refer to Figure 8). ).  The half power beam width (HPBW) and directivity for half-wave dipole are as below:
• HPBW (E plane) = 54 Degrees
• HPBW (H plane) = 58 Degrees
• Directivity = 9.4dB

Most antenna performance measurements are given in decibels. Important figures for a beam antenna are the forward gain, front-to-side ratio, and front-to-back ratio.

Half-wave Dipole Antenna is a single band antenna. There is only one part of a receiving antenna that is active, called the dipole. This type of antenna has the simplest design which consists of a dipole only. Yagi-Uda Antenna is a directive, gain type of antenna that utilizes a number of parasitic directors and a reflector. It is named after the two Japanese inventors (Mr. Yagi and Mr. Uda).

In order to improve the front-to-back ratio, we can add passive element, such as a reflector. The reflector reflects signal coming in from the back of the aerial whilst improving the forward gain. Usually a Yagi-Uda antenna will have one element behind the driven element (called the reflector), and one or more elements in front (called the directors). The reflector will be slightly longer than the driven element and the directors will be slightly shorter. Therefore, the energy is then concentrated in a forward direction.

The Yagi-Uda antenna not only has a unidirectional radiation and response pattern, but it concentrates the radiation and response. The more directors a Yagi-Uda antenna has, the greater the so-called forward gain. Hence, Yagi-Uda antenna has a better performance than half-wave dipole antenna since Yagi-Uda antenna offers excellent gain.

Antenna is an electrical conductor or array of conductors that radiates signal energy (transmitting) or collects signal energy (receiving). During the time when we were still young, we knew that the antenna should be preferably erected as high and be as long as is possible or desirable.

After this experiment, we are more familiar with the radiation patterns and characteristics of the half-wave dipole and Yagi-Uda antennas.  As we can observe from the experiment, the performances of Yagi-Uda and Half-wave dipole antennas are different due to the different structures.

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