The 80 Meter Doublet Antenna — 88 Ft/25Ft 300 Ohm Twin-lead

This is my experiment with the 80 meter doublet antenna, using TV twin-lead wire, which is 300 ohms. This was a spur of the moment project. I built this antenna and quickly tried it out in February of 2013.

My initial aim was actually for a 60 meter dipole antenna. I had a total of 88 feet of 12 gauge copper wire, 44 feet for each leg of the dipole. This was the wire for a future 60 meter dipole, or so I thought.

I also had approximately 25 feet of 300 ohm TV twin-lead wire. I think it is 14 gauge wire.

Ideal All-Band Doublet Configuration

The ideal length for an 80 meter doublet would probably consist of 130 ft. of copper wire and 60 ft. of 450 ohm ladder line wire. It is suggested to run the ladder line directly into the shack, or add around 25 ft. of coax running into the shack.

Homebrew 80 Meter Antenna Construction

I attached 88 ft. of copper wire to 25 ft. of 300 ohm wire. I used a coax connector at the end of the 300 ohm wire, and hooked it up to 100 ft. of RG8X, the gray coax cable. I made my own center insulator using a scrap piece of PVC plastic pipe. I drilled a few holes in it to attach the copper wire and this worked out really well.

Tuning And Finding Resonance

Then the trot back to the Kenwood hf transceiver. This is always the fun part.

I don’t think that it was resonant on any band and I don’t own an antenna analyzer. I rely on my transceiver to find the best match for any antenna. The internal tuner in my rig did tune up this doublet with no problem.

This 80 meter doublet played great on 80M and 40M. I couldn’t believe how well it performed on 40M. It did tune up on 160M, but it was not a good match. It played well on the high bands. I worked Columbia in South America on 20M using 100 watts. Not bad!

80/40 Meter Doublet VS 80/40 Meter Fan Dipole

As a comparison, I matched the compromised 80 meter doublet against an 80/40 meter fan dipole that I have, which is resonant on both bands. Both antennas were mounted about 25 ft. in the air; nothing outstanding in terms of height.

This particular 80 meter doublet was equal to the fan dipole, and at times it brought in a much stronger signal. I am very impressed with the doublet. During this experiment the low bands were not in optimum condition. The bands were fair to bad and this makes it hard to analyze any antenna.

Final Thoughts

This endeavor has made me a firm believer in the doublet. The length for the antenna produced fantastic results, much better than I expected. I found out that a longer length of wire may have been a better choice —about 50 ft. (instead of 25 ft.) of TV twin-lead (300 ohm)—for the All-Band Doublet (80-10 Meters). This antenna is one of the most popular wire antennas in amateur radio. I now see why.

The doublet is an excellent performer and I highly recommend it. The advantage of the doublet over the fan dipole is a whole lot less space and less maintenance. The doublet only consists of one run of wire, whereas the fan dipole consists of two runs of wire or more. The 80 meter doublet replaces several antennas and its effectiveness is superb. And don’t get me wrong, because I’m a strong advocate of the resonant dipole. However, I find myself using the doublet more often than the fan dipole and I’m planning to get it higher in the air for even better results.

Another advantage of the doublet is—the twin-lead wire—which runs perpendicular to the copper wire; it acts as part of the antenna itself. This gives you another angle of radiation for transmit and receive. This seems to be a big factor.

The doublet can be built using several lengths of copper wire and 300 ohm feedline. There are many variations and these antennas are called by different names.

The Big Zapper Antenna

The Big Zapper has gained popularity with many hams. This is another variation definitely worthy of examination.