What is the impedance of a dipole antenna?
What is the impedance of a dipole antenna?
As with any RF antenna, the feed impedance of a dipole antenna is dependent upon a variety of factors including the length, the feed position, the environment and the like. A half wave centre fed dipole antenna in free space has an radiation impedance of 73 Ω, making it ideal to feed with 75 ohm feeder.
How do you calculate dipole impedance?
Before examining the fields radiated by a dipole antenna, consider the input impedance of a dipole as a function of its length, plotted in Figure 2 below. Note that the input impedance is specified as Z=R + jX, where R is the resistance and X is the reactance.
What is the impedance of a 1/2 wave dipole antenna?
73 Ω
The impedance for a half wave dipole antenna in free space is dipole 73 Ω which presents a good match to 70Ω coaxial feeder and this is one of the reasons why coax with this impedance was chosen for many applications.
What is the impedance of 4 element folded dipole antenna?
Explanation: The impedance of folded dipole is four times the impedance of the half dipole. So its impedance is higher than the half dipole.
Does a folded dipole need a balun?
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 impedance of a long wire antenna?
Impedance is highest on the lowest band. Note it is 6850 ohms on 80 meters, decreasing to 1360 ohms on ten meters. This is because more and more half waves are being fed from one feedpoint with increasing frequency….Counterpoises.
| Advantages | Disadvantages |
|---|---|
| inexpensive | require a tuner or matching system |
What is input impedance of simple dipole antenna?
At resonance, the impedance of a half-wave dipole antenna is approximately 70 Ohms, so that the input impedance for a half-wave folded dipole antenna is roughly 280 Ohms.
Does a dipole need a 1 to 1 balun?
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.
