U01 emergency communications antenna

Update: 02. October 2022:

Please read the updated Antenna Page first, to get a basic understanding of EFHW and possible Setups.

The U01 Antenna was built and tested also with the smaller hasp PCB, which can be seen in the Video below, so there you have another Option.

All DL2MAN Antenna PCB´s provide Option for SMA and BNC Connector !

FT114-Version: The „advanced“ PCBs have the Transformer sit in a hole, that can be covered / weather-proofed and provide hasp functionality.

PCB Files (smaller Hasp)

Cover Files (smaller Hasp)

U01 Antenna on smaller HASP (using DX Wire UL, and DX Wire 2mm Polyester chord). Only 257g for a FULL SIZE 80/60/40/20/17/15/10m Antenna. Size like a womans fist.

I´ve created an updated overview Document, taking all the options into consideration:

Updated Version !!!! 27. August 2022:

This PCB is designed for FT140-43 core with 2 in 14 turns and should be able to easily handle 100W. Use 500V silver Mica Capacitor 100p. PCB has footprints for BNC and SMA Connector. The spool was designed a little bit bigger, so it would also carry the amount of wire, when using DX Wire FL ! I personally use UL (Ultralight) by DX-Wire.

FT140 Version: Toroid, Capacitor and SMA connector soldered on PCB.
Cover in position.
completed Antenna
Just 307 grams ready to go…..

This updated PCB just replaces the broadband transformer PCB. Wire lenth etc all stays the same.

End of Update

The Antenna was designed, tested and published by DJ5RE (Tom). Within our DARC Chapter U01 this Antenna has been built multiple times and the concept is proven as very reliable and repeatable.

Introduction to the U01 Antenna and further explainations

I´ve used the same wire lengths as in Tom´s original article (including the loops to connect the segments together,) but I build my own specimen around a FT82-43 core transformer with QRP in mind.

Meanwhile, I´ve created several Options (together with DJ5RE) to build it with FT114-43 or FT140-43. See Updates at the Beginnning of this Page.

See Antenna Main page for a table of what core-size to chose depending on the TX Power and what winding pattern to chose depending on the core size.

This is the concept drawing:

Antenna wire was Ultralight from DX-wire

Rope was Polyester rope 2mm by DX-Wire

Connectors were 2mm RC connectors

Broadband transformer was wound on FT82-43 (other Options available)

Transformer was wound with 0,63mm copper enamelled wire (use 1mm for FT140-43)

This is one set of the required print files (printed in PETG at 0,15mm layer height, 3 shells, 30% infill)

Remark: The following PCB Files are not neccessary, when you use the U01 Spindle PCB (from top of this Page)!

You can use DG1JAN´s PCBs to built the 1:49 broadband Transformer:


Update 09.Sept 2022:

Jan has updated his PCB and has now also the Gerbers on his GitHub. To be sure to have the latest Revision, please download the Files from his Github.

End Update

And these are the Gerber files for my own PCB:

How to wind a Broadband-Transformer and the theory behind it is explained here: