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This project assembles a 49:1 ferrite-core (“FT”) type #43 transformer that matches 50 ohm input to 2500 ohm end fed antenna. It is optimized for 3.5/7/10/14 MHz but will work reasonably well on all amateur bands from 80 meters thru 10 meters with a 135 foot length of wire and a short connection to ground.
An 80-10 end-fed half-wave antenna can be a very good performing part of an HF station. But its performance depends heavily on a well-designed and carefully constructed 49:1 unun, which matches the long wire impedance to within tuning range of operation. But the perfor-mance of an end-fed antenna is also very dependent on height above ground.
Recommended wire lengths and Installation Notes for Unun models 4932, 4935, 9130, 9132 & 9135. Table shows typical SWR relative to installed wire length. SWR will vary based on topography, proximity of nearby structures, configuration of the antenna wire and choice of ground or counterpoise.
Table shows typical SWR relative to installed wire length. SWR will vary based on topography, antenna wire configuration and use of ground or counterpoise. For best results, use the longest wire shown on the table that will fit your installation constraints.
27 mar 2024 · Since we have not seen a good, rigorous measurement of any 49:1 UnUn embedded in a 50-ohm system, I constructed a couple to accomplish that measurement by connecting them in series: 50-ohms to 2.7 kΩ and back to 50-ohms.
I made an antenna for use in shortwave bands (3 MHz to 28 MHz) for amateur radio. There are two UnUn that I made. The first one used FT140-43, it using the winding method used by KN5L.
The End-Fed Half-Wave (EFHW) Dipole Wire Antenna By T. W. Longfellow, N7TWL June 2023 Let’s start with the obvious: The purpose of an antenna at the amateur radio station is to transmit and receive radio signals. The type and design of the antenna is based on any number of parameters: specifically, the frequency or
