What is the impedance of an end fed half wave?
At the centre of the half-wave the impedance is about 70 Ohms [1] and at each end the impedance is several thousand Ohms. The exact impedance at the end depends on the conditions in which it is measured however it usually lies in the range 3,000 – 5,000 Ohms.
What is end fed antenna?
The end fed wire antenna simply consists of a length of wire that is as high and reasonably long as possible. The antenna wire is then typically take out of the radio room, or shack and taken to a horizontal section that runs above obstructions.
What is the impedance of a half wave antenna?
Typically the matching transformer transforms the impedance from the value of around 4,000 or 5,000 Ω at the EFHW antenna feed point down to the 50Ω value of the coaxial feeder. The end fed half wave antenna is also able to provide multi-band operation.
How is energy fed to a half wave antenna?
The most common method of feeding energy to this type of antenna is at the center where the current is maximum and the voltage is minimum. Consequently, the impedance at this point is low and on the order of 72 ohms. This makes it convenient to feed the antenna directly with low impedance 50 ohm coax cable.
How to match half wave antenna to coaxial feeder?
In order to match the end fed half wave antenna to the coaxial feeder, it is necessary to have a matching network or transmission line transformer. The coaxial feeder is likely to be 50Ω and the antenna impedance is possibly around 4000 or 5000Ω, the impedance needs to be matched. Often a transformer is used to perform this match.
What is the impedance of an end fed transformer?
This means that the end fed wire antenna, which has a very high impedance of around 2500 Ohm, is transformed to an impedance of 50 Ohm. This impedance suits best to most tranceivers. The transformer consists of 2 primary windings and from 14 secondary windings. This gives a ratio of 1 to 7.