BEGINNERDIY PORTABLE ANTENNAS
BUILD YOUR
FIRST DIPOLE
A simple wire antenna you can build in an afternoon and use at your next park.
One of the most rewarding projects in amateur radio is building an antenna you can take into the field and use to make contacts. A homemade dipole is lightweight, cheap and easy to build with basic tools, and it teaches you how antenna length, frequency and installation affect performance.
1. What a Half-Wave Dipole Is
A dipole is two wires reaching out in opposite directions from a center feedpoint. The coax center conductor feeds one side and the shield feeds the other.
A half-wave dipole is about one-half wavelength tip to tip, so each leg is about one-quarter wavelength.
2. Calculating Wire Length
Total length in feet = 468 ÷ Frequency in MHz
Each leg in feet = 234 ÷ Frequency in MHz
These give approximate starting dimensions for a typical wire dipole.
| BAND | FREQUENCY | TOTAL LENGTH | EACH LEG |
|---|---|---|---|
| 80m | 3.600 MHz | 130 ft | 65.0 ft |
| 60m | 5.357 MHz | 87.4 ft | 43.7 ft |
| 40m | 7.200 MHz | 65.0 ft | 32.5 ft |
| 30m | 10.125 MHz | 46.2 ft | 23.1 ft |
| 20m | 14.200 MHz | 33.0 ft | 16.5 ft |
| 17m | 18.100 MHz | 25.9 ft | 12.9 ft |
| 15m | 21.200 MHz | 22.1 ft | 11.0 ft |
| 12m | 24.900 MHz | 18.8 ft | 9.4 ft |
| 10m | 28.500 MHz | 16.4 ft | 8.2 ft |
| 6m | 50.100 MHz | 9.3 ft | 4.7 ft |
Beginner tip: 20 meters (highlighted) through 10 meters are the easiest portable dipoles. 80 and 60 meters are very long for a park setup.
About 60 meters: it isn’t a full band like the others. In the U.S. it’s a narrow allocation near 5.3–5.4 MHz with its own rules, so check the current band plan before you transmit. The chart uses 5.357 MHz, a common operating frequency.
Cut a little extra for tuning and connections, and verify with an antenna analyzer. Two things change the numbers in the real world:
- Insulated wire usually resonates a bit lower than bare wire, so you’ll trim a little.
- An inverted-V typically ends up a few percent shorter than a flat dipole, often around 3–5%.
3. Materials Needed
- Insulated stranded copper antenna wire, commonly 14–18 AWG
- Center insulator or dipole feedpoint connector
- Two end insulators
- 50-ohm coaxial feedline
- A coax connector that fits your radio
- Rope or paracord for supports
- Wire cutters, tape measure and basic hand tools
- Antenna analyzer or SWR meter
- Optional: 1:1 current balun or common-mode choke
Flexible stranded wire is easier to roll up, carry and deploy than solid wire. A 1:1 current balun or choke at the feedpoint helps keep RF from flowing on the outside of the coax shield.
4. Build a Simple 20-Meter Dipole
Let’s build one for the 20-meter band, near 14.200 MHz. 468 ÷ 14.200 is about 33 feet total, so each leg is about 16 feet 6 inches.
- Cut two pieces of antenna wire a little longer than 16 ft 6 in.
- Attach one end of each wire to the center insulator.
- Connect one wire to the coax center conductor and the other to the shield connection.
- Secure the connections and add strain relief.
- Attach an end insulator to the outer end of each wire.
- Tie support ropes to the end insulators.
- Raise the antenna to where you’ll operate it.
- Check it with an analyzer before making final adjustments.
5. Installing Your Dipole
A dipole doesn’t have to be perfectly horizontal to work. Portable operators commonly use three layouts:
Keep wire ends well above where people walk or touch them.
6. Does Antenna Height Matter?
Yes. Height above ground changes the radiation pattern and the feedpoint impedance. A fairly low horizontal dipole sends more signal at high angles, which can suit shorter-range contacts on the lower HF bands. As height grows relative to wavelength, the pattern favors lower takeoff angles.
For portable work, height usually depends on the trees, mast, safety and setup time. A modestly elevated dipole can still make plenty of contacts, and tuning it at about its operating height gives the most accurate result.
7. Do You Need a Tuner?
A properly built single-band dipole can often run without one. But feedpoint impedance shifts with height, wire layout and surroundings, so a tuner may still help. Also, low SWR at the radio doesn’t prove the antenna is radiating well, especially if the feedline is lossy. More in SWR Basics.
8. Common Dipole Mistakes
Final Thoughts
Building a dipole is one of the best ways to learn practical antenna basics. It’s inexpensive, reliable and capable of excellent performance. Ready for more than one band? Try a linked dipole.
KPC FIELD REMINDER: Antenna formulas give starting points, not guaranteed measurements. Wire type, height, nearby objects and the final configuration all affect tuning. Measure, adjust and verify.
73 from KPC — Build It, Test It, Get Outside, and Get on the Air!
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Get Outside. Get On The Air.
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