A folded dipole is an antenna consisting of two parallel conductors connected at both ends, forming a closed loop‑shaped structure, with the feed point at the center. The total length of the antenna is half a wavelength, which is why it is also called a half‑wave folded dipole antenna.
Frequency range
The half-wave folded dipole antenna operates over a frequency range of approximately 3 kHz to 300 GHz, and is primarily used in television receivers.
Structure and Operating Principle of the Half-Wave Folded Dipole
This type of antenna is often used in combination with array antennas to increase the input impedance at the feed point. The most typical application is the Yagi antenna. The figure below shows a half-wave folded dipole antenna.
Compared with a conventional dipole antenna, the folded dipole antenna introduces an additional parallel conductor (i.e., another wire or rod). By placing several parallel conductors side by side with insulation between them, an array-type antenna can be formed.
The figure below illustrates the operating principle of a half-wave folded dipole antenna when excited.
If the diameter of the main conductor is the same as that of the parallel conductor in the folded dipole, the feed-point impedance of the antenna increases by a factor of four (the square of two). This increase in feed impedance is the main reason why the folded dipole antenna is so widely used. Due to its twin-lead construction, its typical impedance is about 300 Ω.
Radiation mode
The radiation pattern of a half-wave folded dipole is identical to that of a half-wave dipole antenna. The figure below shows the omnidirectional radiation pattern of this half-wave folded dipole antenna.
The half-wave folded dipole antenna is used in applications where maximum power transfer is required and where a higher impedance is needed.
This folded dipole is the main radiating element in a Yagi antenna. The figure below shows a Yagi antenna (which will be discussed in detail later). In this antenna, the feed point is connected to the folded dipole as the key component. Over the past few decades, this type of antenna has been widely used for television reception.
The following are the advantages of the half-wave folded dipole antenna.
1.Receives balanced signals.
2.Captures desired signals from a specific frequency band without loss of quality.
3.The folded dipole maximizes signal strength.
To learn more about antennas, please visit:
Post time: Jun-12-2026
