Terminated End Fed Vee Antenna (TEFV) – It Is a travelling wave antenna, which has a constant current distribution along its length. Antennas usually used by radio amateurs are resonant standing wave types like dipoles. It is built to a specific tuned length so that a standing wave is set up on the antenna element. This is efficient and narrow band, only works on the fundamental frequency. In a traveling wave antenna there are no standing waves on the antenna element as the power that would be reflected back from the end of the antenna is absorbed by the terminating resistor. Typically this is 25% of the power applied to the antenna. The polarization of the TEFV is a mixture of vertical and horizontal that results in a kind of elliptical polarization. The main advantages of terminated end fed V antennas are its broadband nature and no tuner requirement. It provides a non-resonant antenna with exceptionally wide bandwidth, matching a 50 ohm coaxial cable transmission line with a VSWR of less than 2:1 from 1.8 MHz to 30 MHz.
The critical parts in TEFV antenna are 9:1 unun transformer and terminating resistor. Main problem was in constructing 9:1 Unun with correct size wire for windings. Winding with wrong wire size resulted in poor impedance transformation and high through loss. The resistor value should be 10% higher than the transformer output impedance. So for a 9:1 transformer (50 ohms to 450 ohms) the termination should be 500 ohms.
DIY – Terminated End Fed Vee Antenna (TEFV)
The critical parts in TEFV antenna are 9:1 unun transformer and terminating resistor. Main problem was in constructing 9:1 Unun with correct size wire for windings. Winding with wrong wire size resulted in poor impedance transformation and high through loss. The resistor value should be 10% higher than the transformer output impedance. So for a 9:1 transformer (50 ohms to 450 ohms) the termination should be 500 ohms.
DIY – Terminated End Fed Vee Antenna (TEFV)
