What is a folded dipole?
What is a folded dipole?
A folded dipole is an antenna, with two conductors connected on both sides, and folded to form a cylindrical closed shape, to which feed is given at the center. The length of the dipole is half of the wavelength. Hence, it is called as half wave folded dipole antenna.
What is true about folded dipole?
Explanation: The impedance of folded dipole is four times the impedance of the half dipole. So its impedance is higher than the half dipole. Since folded dipole is a balanced antenna we use a balanced feeder so Balun is used.
Is a folded dipole directional?
The radiation pattern of half-wave folded dipoles is the same as that of the half-wave dipole antennas. The following figure shows the radiation pattern of half-wave folded dipole antenna, which is Omni-directional pattern.
Is a folded dipole balanced?
Like the basic dipole, the folded dipole antenna is a balanced antenna, and needs to be fed with a balanced feeder. Unbalanced feeders can be used provided that a balun (unbalanced to balanced transformer) is used.
What is the main difference between half-wave and folded dipole?
Suppose, for example, only makes sense to compare a half-wave dipole (that is used most commonly) to a half-wave folded dipole and the only distinction in electrical features is that the dipole has approximately 73 ohms impedance whereas the folded dipole consists of 4 times that impedance, or approximately 300 ohms.
Is a balun needed for a dipole antenna?
The use of a balun will prevent the coax radiating any power or picking up any noise. In many practical situations it is possible to operate the dipole satisfactorily without one, but there may be a slight increased risk of interference if one is not used. Simple baluns can be bought from antenna suppliers, or made.
What is the main application of folded dipole antenna?
Applications of folded dipole antenna The folded dipole antenna is ideal for use as a feeder element in Yagi antenna, Parabolic antenna, turnstile antenna, log periodic antenna, phased and reflector arrays, etc. It is also used in radio receivers and is commonly used in TV receiver antennas.
What is difference between dipole and folded dipole antenna?
The folded dipole has a wider bandwidth than a single dipole. They can be used for transforming the value of input impedance of the dipole over a broad range of step-up ratios by changing the thicknesses of the wire conductors for the fed- and folded-sides.
What is the impedance of a folded dipole antenna?
As with all antennas, the input impedance of the folded dipole is defined as the ratio of voltage to current at the antenna feed point. The half-wave folded dipole can be made resonant with an impedance of approximately 300 2 which matches a common transmission line impedance (twin-lead).
Does a dipole need a 1 to 1 balun?
Do I need to ground a dipole antenna?
If you use a “complete” antenna like a dipole or a ground plane (that is, one that doesn’t require your feedline to connect to ground), you don’t need a RF ground, as long as you keep common-mode currents off your feedline. A “current” or “choke” balun is most commonly used for this.