How Does A Dipole Work?

What does a dipole antenna look like?

A dipole antenna commonly consists of two identical conductive elements such as metal wires or rods.

Most commonly it consists of two conductors of equal length oriented end-to-end with the feedline connected between them.

Dipoles are frequently used as resonant antennas..

Does a dipole antenna have to be straight?

Dipole antennas need not be installed in a horizontal straight line. They are generally tolerant of bending, sloping or drooping as required by the antenna site. Remember, however, that dipole antennas are RF conductors. … (So does the coax shield, unless it is routed at 90° from the antenna.)

Is a dipole antenna omnidirectional?

The radiation pattern of a dipole is similar the the shape of a ring doughnut. Therefore the dipole is omni directional only in its orientation i.e a vertical dipole is omnidirectional horizontally. Directly above and below the dipole the is virtually no radiation.

How does a dipole radiate?

The name ‘di-pole’ indicates that the dipole antenna consists of two poles or items – two conductive elements. Current flows in these two conductive elements and the current and the associated voltage causes an electromagnetic wave or radio signal to be radiated outwards from the antenna.

What is a Hertzian dipole?

The Hertzian dipole is a theoretical dipole antenna that consists of an infinitesimally small current source acting in free-space. Although a true Hertzian dipole cannot physically exist, very short dipole antennas can make for a reasonable approximation.

Is a dipole directional?

The radiation pattern of a dipole is similar the the shape of a ring doughnut. Therefore the dipole is omni directional only in its orientation i.e a vertical dipole is omnidirectional horizontally. Directly above and below the dipole the is virtually no radiation.

Where is dipole antenna used?

The dipole antenna is a particularly important form of RF antenna which is very widely used for radio transmitting and receiving applications. The dipole is often used on its own as an RF antenna, but it also forms the essential element in many other types of RF antenna.

Is a dipole balanced or unbalanced?

Antennas can be balanced or unbalanced. A balanced antenna is symmetrical about the feed point (e.g. a dipole) whereas an unbalanced antenna is not systematical about the feed point (e.g. a Windom). In the real world all antennas are unbalanced to some degree.

What balun do I need for a dipole?

The overall length of the multi-band dipole antenna should be shorter than one-half wavelength as shown in Table 1. For best efficiency, ladder line feed and a good antenna tuner with balanced connections are required. The ideal balun is a 1:1 ratio DX Engineering special application tuner balun.

How long is a dipole antenna?

Dipole Antenna Length. When determining how long to make each leg of a Dipole antenna, dividing the frequency in MHz into 468 will give the overall length. To find the half wave, divide that number by two. This will give you the length of each leg of the antenna.

What is simple dipole antenna?

A dipole antenna is the simplest type of radio antenna, consisting of a conductive wire rod that is half the length of the maximum wavelength the antenna is to generate. … Radio frequency voltages are applied to dipole antennas at the center, between the two conductors.

Why dipole antennas are a half wave long?

This is slightly shorter than the equivalent length of a wave travelling in free space as the antenna conductors affect the wavelength. The voltage and current levels vary along the length of the radiating section of the antenna. This occurs because standing waves are set up along the length of the radiating element.

What is the impedance of a dipole?

The values of the real and imaginary input impedance are well known for a dipole antenna. The impedance varies vs. frequency (wavelength compared to the antenna physical length). The half wavelength resonant frequency real part of the impedance should be 73 ohms, and the imaginary part should be 42.5 ohms.

Does a dipole need a balun?

Paul, a dipole does not *have* to have a balun. Having one may help prevent RF from coming down the line into the shack and may improve the radiation characteristics of the dipole, but I’ve run dipoles connected straight to coax without a problem. Put one up without a balun and see how it works for you.