Contents
What is the feed point impedance of a dipole?
Feeding a dipole antenna. Ideally, a half-wave dipole should be fed using a balanced transmission line matching its typical 65–70 Ω input impedance.
How is antenna impedance load calculated?
For maximum power to be transferred from the generator to the antenna, the ideal value for the antenna impedance is given by: The * in the above equation represents complex conjugate. So if ZS=30+j*30 ohms, then for maximum power transfer the antenna should impedance ZA=30-j*30 ohms.
What does a dipole antenna need to radiate electromagnetic waves?
The basic dipole antenna To allow charge carriers to oscillate, we need an alternating source voltage. At first the voltage source, Vs causes current to flow. This current causes a magnetic field (shown by the circles around the wire). This magnetic field extends outwards 90 degrees to the dipole arms.
How is the feed impedance of a dipole determined?
The feed impedance of a dipole is determined by the ratio of the voltage and the current at the feed point. A simple Ohms Law calculation will enable the impedance to be determined.
How is the length of a dipole antenna determined?
By matching the feed impedance of the dipole to the source or load, the antenna is able to operate to its maximum efficiency. The length of a half wavelength dipole is 468/F (MHz). The feed impedance of a dipole is determined by the ratio of the voltage and the current at the feed point.
Is it possible to feed a half wave dipole?
Although the most common for of dipole is the half wave dipole, others can be multiples of a half wavelength. It is therefore possible to feed the dipole at any one of these voltage minimum or current maximum points which occur at a point that is a quarter wavelength from the end, and then at half wavelength intervals.
What are the minimum voltage maximum points for a dipole?
Most dipoles tend to be multiples of half wavelengths long. It is therefore possible to feed the dipole at any one of these voltage minimum or current maximum points which occur at a point that is a quarter wavelength from the end, and then at half wavelength intervals.