Build a 20 Meter Loop Antenna Under $100 – Step‑by‑Step Guide

Struggling to get a decent HF antenna without spending a fortune or sacrificing space? This guide shows you how to build a 20 meter loop antenna for under $100 that actually works—step by step. You’ll learn the exact parts, wiring, tuning, and mounting tricks needed to get on the air fast.

Why a 20‑Meter Loop Antenna Beats Expensive Kits

A compact loop delivers solid HF performance in tight quarters where a full‑size dipole won’t fit. Unlike pricey commercial kits, this DIY version uses cheap hardware‑store parts and simple hand tools. The result is a resonant antenna that pulls in distant stations without the frustration of mismatched SWR.

Parts List & Cost Breakdown

12 ft of 14‑AWG copper wire (house‑wire grade) – ~$5
Small variable capacitor (~365 pF) – ~$8
SO‑239 coax connector – ~$4
PVC pipe or wooden dowel (20 in. form) – ~$3
RG‑58 coax feed line (short piece) – often already on hand
Misc. screws, solder, heat‑shrink tape – ~$5

Total stays under $25, leaving plenty of budget for extras like weatherproofing.

Building the Loop: Step‑by‑Step

Form the loop – Wrap the copper wire tightly around a 20‑inch PVC circle, leaving a small gap for the capacitor.
Install the capacitor – Solder the variable capacitor across the gap; this creates the tuned circuit.
Attach the feed point – Solder the SO‑239 connector opposite the gap, connecting the coax shield to the loop and the center pin to the capacitor side.
Check continuity – Ensure there are no shorts between shield and center conductor before powering up.

Tuning & Testing Your Antenna

Connect the loop to your transmitter with a short RG‑58 piece.
Set power low, sweep the variable capacitor while watching the SWR meter.
The sweet spot appears as a sharp dip; lock the capacitor there with hot glue or a set screw.
In my build, resonance hit 14.180 MHz with SWR < 1.5:1—perfect for casual DXing.

Weatherproofing & Mounting Tips

Wrap each solder joint in self‑amalgamating tape, then cover with heat‑shrink tubing to block moisture.
Add a dab of silicone sealant over the tape for humid climates.
Mount the loop on a balcony rail, fence post, or tree branch using zip ties; keep it clear of large metal objects that could detune it.

Final Thoughts & Next Steps

For under $100 you now have a resonant, efficient 20‑meter loop antenna that fits small spaces and delivers real HF performance. The sense of hearing a faint signal come through clearly after you’ve tuned it yourself is unmatched by any store‑bought kit. Grab the parts, follow the steps, and get on the air today—then share your results in the comments or drop me an email. Happy building!