Drahtantenne

Drahtantenne is a generic term for a radio antenna made primarily from wire. Such antennas are widely used in amateur radio, shortwave reception, and home radio installations because they are relatively simple to construct and can operate over a broad range of frequencies. The key principle is that a straight conductor or a pair of conductors radiates electromagnetic energy when fed with an alternating current at radio frequencies. The electrical length of the wire, its height above ground, and its orientation determine its resonance, impedance, and radiation pattern.

The most common types are the half-wave dipole, the long-wire antenna and the end-fed configurations. A half-wave dipole consists of two equal wires fed in the center with a balanced feed. It is resonant at wavelengths close to its total length (about lambda/2) and typically presents an impedance around 70 ohms, often requiring a balun when fed from coax. A long-wire or Langdrahtantenne uses a single wire longer than a quarter wavelength, supported between poles or structures, sometimes with a counterpoise or radial system to improve efficiency. End-fed antennas use a single wire of roughly lambda/2, fed at one end with an impedance-matching network; they are simple to install but usually need a suitable counterpoise. Folded dipoles consist of two parallel wires connected at the ends and provide higher feed impedances, commonly fed with balanced or higher-impedance lines.

Installation considerations include support structures, insulation, weather resistance, and proper RF grounding. The height and orientation influence the radiation pattern and polarization. Wire antennas are versatile and cost-effective, but their performance is frequency-dependent and often optimized with matching networks or tuners for multi-band operation.