4/1 (200 Ohm to 50 Ohm) UNUN as “pre-match unit” for use with multiband monopole and wire verticals.
Trap- or coilless wire or rod antennas with a length varying from 6 to 14 meters are popular because of their simplicity.
With some compromise, they can be deployed on multiple frequency bands.
The feedpoint impedance of such non-resonant vertical antenna is relatively random, causing high VSWR values.
In order to bring the impedance within the range of an average external or built-in asymmetric antenna tuner, an 4/1 UNUN (Unbalanced to Unbalanced) impedance transformer is used, as a pre-match unit.
At the same time, the UNUN assures reasonable low VSWR values on the coaxial feedline, avoiding excessive losses.
As with any vertical, the efficiency and radiation pattern is largely depending on the radial field laid out below the antenna.
This can vary from a simple grounding rod, in temporarily or emergency set-ups, to an extensive plane of radials in more permanent installations.
The ON7FU 4/1 UNUN is built on a large ferrite torroid, using Teflon wire for the windings.
In this way the UNUN can, with a conservative margin, withstand 1200 Watts, even under highly mismatched conditions.
- Frequency range: 1,5 to 30 MHz
- Max Power: 1200W PeP @ VSWR <2,0/1 , (ICAS)
- Insertion loss: < 0,1 dB
- Intrinsic VSWR: <1.4/1
- Stainless steel hardware.
- Fully waterproof
- Shock proof Polycarbonate housing
- Simple installation on the antenna support tube.
Price: 96 Euro.
- Option N-connector (N-connector instead of SO239): + 6 Euro.