Maximize Your QRP Setup with This Ultra-Portable End-Fed Antenna
If you’re a QRP operator looking to maximize your signal while minimizing your gear, building a portable end-fed antenna could be your perfect solution. In this guide, I will attempt to walk you through how to build a portable QRP antenna for hiking and camping—designed specifically for QRP radio operation with easy-to-follow steps
What Is QRP, and Why Does It Matter?
QRP refers to operating a radio with very low power, typically 5 watts or less. In the world of ham radio, the goal is often to make contacts over long distances with minimal power—sometimes even just a few milliwatts!
It's a challenge that requires not just good equipment, but the right antenna. That’s where this end-fed antenna design comes in. It’s compact, efficient, and perfect for those of us who love portable setups.
Why End-Fed Antennas Are Perfect for QRP
End-fed antennas are a breeze to set up. Just toss one end over a branch or tie it to a pole, and you’re good to go. For portable operations, that kind of simplicity makes them a perfect choice, especially when you're on the move and need something quick.
But it’s not just about convenience—end-fed antennas are highly efficient when tuned right. They’re designed to handle high impedance (about 3200Ω), and with a little help from an impedance matching device called a UNUN transformer, your radio’s 50Ω input is happy. This ensures that your signal is strong and clear, even with only 5 watts of power, which is essential for any QRP operator.
Impedance Matching: Why It’s So Important
When you use an antenna, the impedance needs to match your radio’s input. If it doesn't, you’ll end up with a poor signal and high power loss.
In this antenna design, the 64:1 UNUN transformer is the key. It matches the antenna’s high impedance to the radio’s 50Ω input, ensuring your radio works efficiently with minimal loss.
This transformer plays a crucial role in making the antenna perform well, especially for QRP operators who are working with low power.
Step-by-Step: How to Build The QRP End-Fed Antenna
Building this antenna is easier than you might think, and it doesn’t require fancy or hard-to-find materials. Here's everything you need to know to get started.
Materials You’ll Need for Your Portable QRP Antenna
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BNC Connector: This is what connects your antenna to your radio.
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FT50-43 Toroid Core: A small magnetic ring used to create the impedance transformer.
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Insulated Copper Wire (0.25mm enamel wire): Used to wind the toroid and form the antenna wire.
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100pF Capacitor (1000V): Keeps the circuit stable and helps with tuning.
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28.5mm PVC Pipe: This is your coil form for the inductor.
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Glue or Resin: Protects the components and ensures everything stays secure.
BNC Connector: This is what connects your antenna to your radio.
FT50-43 Toroid Core: A small magnetic ring used to create the impedance transformer.
Insulated Copper Wire (0.25mm enamel wire): Used to wind the toroid and form the antenna wire.
100pF Capacitor (1000V): Keeps the circuit stable and helps with tuning.
28.5mm PVC Pipe: This is your coil form for the inductor.
Glue or Resin: Protects the components and ensures everything stays secure.
How to Build an End-Fed Antenna for Portable Ham Radio Operation
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Wind the Toroid
Start by winding two turns of wire in one direction, and then add seven more in the same direction. Now, cross the wire and wind seven more in the opposite direction. Keep the crossing wire slightly to the side—this will make installing the SMA connector a lot easier later on.
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Create the Inductor
Grab the PVC pipe and wrap 50 turns of wire around it to create your inductor. For the best performance, aim for an inductance of around 34µH.
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Attach the Antenna Wire
Now, take a 0.95-meter length of wire and attach it to the inductor. Then, connect the other end of the wire to the BNC connector. Finally, add another 2 meters of wire after the connector to complete the antenna.
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Finalize the Circuit
Install the 100pF capacitor between the center conductor (the part that carries the signal) and ground. After that, solder all the connections and insulate them with glue or resin to protect everything from the elements.
Wind the Toroid
Start by winding two turns of wire in one direction, and then add seven more in the same direction. Now, cross the wire and wind seven more in the opposite direction. Keep the crossing wire slightly to the side—this will make installing the SMA connector a lot easier later on.
Create the Inductor
Grab the PVC pipe and wrap 50 turns of wire around it to create your inductor. For the best performance, aim for an inductance of around 34µH.
Attach the Antenna Wire
Now, take a 0.95-meter length of wire and attach it to the inductor. Then, connect the other end of the wire to the BNC connector. Finally, add another 2 meters of wire after the connector to complete the antenna.
Finalize the Circuit
Install the 100pF capacitor between the center conductor (the part that carries the signal) and ground. After that, solder all the connections and insulate them with glue or resin to protect everything from the elements.
