Chapter 4 Wireless Technology
155
Dipole
The dipole is one of the most common radio antennae used. What makes it
popular is it is relatively inexpensive to manufacture when compared with many
other antenna styles. The dipole is commonly used as a client or receiver antenna
rather than as a broadcast antenna. The dipole antenna is bidirectional, as seen
in Figure 4-7. Rotating the antenna until the dipole aligns with the source of the
radio wave transmission can enhance the received signal.
Yagi
The Yagi antenna is used for point-to-point links. It is a directional-type
antenna. A Yagi antenna is typically designed from many radio antenna elements
(tubes). Each element is progressively larger or smaller than the main element
by approximately 5%. The way the Yagi antenna enhances the radiation of the
electromagnetic wave is beyond the scope of this textbook. For now, just note and
recognize the shape of the Yagi antenna and its electromagnetic wave pattern.
Some Yagi antennae are constructed inside a metal tube to further enhance the
reception and transmission of electromagnetic waves. See Figure 4-8.
Figure 4-7.
Basic antenna
styles and the
electromagnetic
wave patterns they
produce.
Electromagnetic
Wave Pattern
(as viewed from overhead) Antenna
Omni
Dipole
Yagi
Flat panel
Parabolic
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Chapter 4 Wireless Technology
155
Dipole
The dipole is one of the most common radio antennae used. What makes it
popular is it is relatively inexpensive to manufacture when compared with many
other antenna styles. The dipole is commonly used as a client or receiver antenna
rather than as a broadcast antenna. The dipole antenna is bidirectional, as seen
in Figure 4-7. Rotating the antenna until the dipole aligns with the source of the
radio wave transmission can enhance the received signal.
Yagi
The Yagi antenna is used for point-to-point links. It is a directional-type
antenna. A Yagi antenna is typically designed from many radio antenna elements
(tubes). Each element is progressively larger or smaller than the main element
by approximately 5%. The way the Yagi antenna enhances the radiation of the
electromagnetic wave is beyond the scope of this textbook. For now, just note and
recognize the shape of the Yagi antenna and its electromagnetic wave pattern.
Some Yagi antennae are constructed inside a metal tube to further enhance the
reception and transmission of electromagnetic waves. See Figure 4-8.
Figure 4-7.
Basic antenna
styles and the
electromagnetic
wave patterns they
produce.
Electromagnetic
Wave Pattern
(as viewed from overhead) Antenna
Omni
Dipole
Yagi
Flat panel
Parabolic

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