End-fed half-wave antenna EFHW 8 band
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End-fed half-wave antennas (EFHW) work in principle similar to a Zepp or Fuchs antenna. Because of the one-sided feed, such a wire antenna is easy to set up. In addition, these antennas have a relatively high efficiency.
The problem with many portable antennas and antennas for confined spaces is the low efficiency of the antennas. Very shortened verticals need many radials for high efficiency, a dipole would need two guy points and a heavy feed line in the middle. This is usually not feasible on holiday or when space is limited.
An antenna concept that has been known for many years, such as the half-wave antenna, provides a remedy. Half-wave antennas can be fed from the end, thus eliminating the heavy feed line in the middle and making the antennas easier to install. Thus, a light fishing rod for the balcony or a suitable tree next to the house is often sufficient. The greater length (λ/2 instead of λ/4) brings significantly increased efficiency. Single antennas for the lower bands use an extension coil.
The relatively high impedance at the base of the antenna is brought close to 50 ohms by a supply transformer (UnUn) with a relatively high transfer ratio of 1:50... Built-in tuners can cope well with this. In some cases, no tuner is needed at all, and there is no need for counterweights. This is another argument in favour of this antenna design, especially on holiday or when space is limited. And - the transformer can be designed more easily for high voltages, so end-fed half-wave antennas are also possible for higher powers.
All power specifications in Watt PEP. The Kelemen Endfed antennas have a PL socket as connection, the output is sideways or downwards, depending on the mounting. Insulators are provided at the balun and at the end of the wire for mounting. In addition, guy wire may be required. For mounting we suggest cable ties or similar, a retaining plate is attached to the transformer.
|Length [m]||40 m|
|Max. Power [W]||200 W|
|Antenna Type||Omni-directional Antenna|
|Design of antenna||Endfed Halfwave ant. (EFHW)|
|Weight [kg]||1.48 kgs|