2023-F-008 | 1/2 Unun for short low band verticals

Function

It is generally known that vertical antennas are the best choice for working DX on the low amateur HF bands. (Especially as TX antennas).

In many cases, because of the long wavelength it is not practical to erect full size antennas for 160m and 80m, and some type of loading is required to shorten the antenna. Capacitive top loading, using “loading wires” is recommended, both electrically and mechanically. Examples are top loaded quarter wave verticals , “Vertical T monopoles” and “Inverted L” antennas.

A consequence of shortening the antenna by means of loading is a lowered radiation resistance at resonance. Values of 25 Ohms and less are common, which cause high VSWR when feeding the antenna directly. In order to match the antenna, often a ½ UNUN is used, which presents a “plug and play” solution.

Mechanical Characteristics

• Optimized 61 mm diameter toroidal ferrites
• Heat resistant teflon coaxial cable with high breakdown voltage.
• Professional 50 Ohms N-connector or SO239 connector. (IP66 after sealing with self- vulcanizing tape or equivalent).
• Stainless steel M6 antenna connections. Stainless steel type 316 More info.
• Waterproof (IP64) and shock proof polycarbonate UV resistant enclosure. More info.
• Weight: +/- 500 g.

Electrical properties

• Impedance transformation ratio: 1/2
• Max. power:
• 2400 W PeP @ VSWR < 2.0/1 (ICAS)
• 1200 W PeP @ VSWR < 2.0/1 (CCS)
• For ICAS and CCS power definitions, More info
  
  
• Deployable frequency range: 1.0 to 10 MHz.
• Insertion Loss: < 0.1 dB