What Are the Different Types of Dipole?

A full-wavelength dipole ^[1] is a dipole with a length of one wavelength. In microwave systems, dipole antennas are widely used, and are commonly used as antenna array elements and exciters on reflective surfaces. Its characteristics change with relative length L / . When the Hertzian dipole antenna ^{[1] is} increased by one wavelength, the effect on the radiation pattern is small. When the half-wavelength dipole is increased by one wavelength, its gain is only increased by about 10%, and when the full-wavelength dipole is added by one wavelength, its gain is increased by 75%.

A full-wavelength dipole is a dipole with a length of one wavelength.

A full-wavelength dipole is the basic element of a broadband microwave antenna. It is characterized by a large radiation resistance and a fairly flat resonance curve. Its input impedance varies widely and is determined by the ratio of its length to its diameter. The smaller the ratio, the smaller the input impedance and the larger the bandwidth. Since its center point is a voltage node, a metal pillar can be used as a support in the center. There are many practical structures for full-wavelength dipoles (see figure). In addition to tube dipoles with balanced or unbalanced feed that are round or streamlined (in order to reduce wind resistance when installed horizontally), there are also various flat dipoles.

The characteristics of different dipole antennas change with the relative length L / . Hertz dipole antenna ^[1]

The short dipole antenna has a small input impedance. For example, if L = / 10, the input impedance is about 4. For a half-wavelength dipole antenna, the input impedance is 73.1, and for a full-wavelength dipole antenna, The input impedance is large, but not infinite, and it is significantly affected by the diameter of the wire.