Longwire Antenna

The longwire is a straight wire several wavelengths long, fed at one end. Unlike a random end-fed wire, a true longwire develops directivity along the wire direction.

Geometry in SimTX

A single horizontal wire running along the azimuth with realistic sag, default length 21 m; a length of 0 selects two wavelengths at the operating frequency.

Characteristics

• Typical gain around 4 dBi with lobes that press toward the wire direction as the wire gets electrically longer.
• Typical takeoff angle around 20 degrees.
• Multi-band by nature: it presents workable (though rarely excellent) matches on many frequencies, with SWR varying between harmonics. Expect a rougher match than a resonant dipole; a tuner-style loss is reflected in the higher default feedline loss (1.2 dB).
• Directional along the wire run: point the azimuth roughly toward the target.

When to use

When simulating a simple field or shortwave-listener style station with one long wire, or when multi-band capability matters more than a clean match. For a serious single band, a resonant Dipole Antenna usually wins.