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Winding the CAHRtenna Artemis Toe-Roid – 49 :1 Unun Transformer

The CAHRtenna Artemis is a 49:1 End Fed Half Wave Dipole (EFHW) Antenna designed for portable amateur / ham radio use on; 10, 15, 20, and 40-meter amateur radio bands. It’s designed as a lightweight but rugged kit that any ham will be able to assemble with basic tools that are readily available in most hamshacks. The antenna has been tested at 50w digital and 100w SSB.

Some of the feedback we have gotten about the CAHRTenna Artemis included questions about wiring the 49:1 UnUn Transformer. Here is an excerpt from a longer prototype build video I did link below:

Here is the current FAQ for the antenna:

Q: What is the material used for the frame?
A: HP PA 12 or Polyamide 12 Nylon, it is strong, durable, and heat-resistant.

Q: What type of wire do you use?
A: It’s 22AWG silicone jacketed multi-strand tinned copper wire.

Q: Can I get a SO-239 version?
A: No, right now it comes with a female BNC connector. You can fit an adapter to the BNC connector if necessary.

Q: What toroid is it?
A: It is a t140-43 mix ferrite core.

Q: Can it do 80 meters?
A; The antenna kit comes with approximately 90’ for 22 AWG silicone jacketed multi-strand tinned copper wire. We suggest starting with 70’ for the element and 20’ for the counterpoise and tuning from there, you could vary the length of the element for 80 meters or any other frequency but the frame is only designed to hold enough wire for a 40-meter antenna.

Q: Can I just buy the frame?
A: No, right now the antenna is sold as a complete kit. This might change in the future.

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