FT44 = Flat Top 44 foot Dipole

The FT44 is a popular antenna - a 44 foot dipole fed with balanced line and a tuner. I don't know who used it first, but W4RNL proposed it as a good backup antenna, or as an only wire antenna for 40 meters and up:
Only One Wire∞.

I have considered it for RV use since it will (just barely, sort of) fit on a pair of SD20 poles (with a couple feet hanging on each end). See SD20Dipole for mechanical details.

So let's assume we have a 44 foot flat top on a 25 foot pole (such as a telescoping flagpole). That will fit nicely into an RV camping space.

Let's take a look at some models and see how it looks. #20 wire, 100 watts, medium high accuracy ground (.006,13), 450 ohm window line 10 feet long to remote tuner, 100/1000Q, 10pf stray C:

40 meters

• 7200 khz
• 25.5 - j 630 feedpoint Z
• 1258v 1.98a feedpoint
• 5.7 dbi straight up (NVIS)

60 meters

• 5370 khz
• 11.7 - j 1110 feedpoint Z
• 3250v 2.9a feedpoint
• 5.11 dbi straight up (NVIS)

80 meters

• 3550 khz
• 4.8 - j 1950 feedpoint Z
• 8.9kv, 4.6a feedpoint
• 3.0 dbi straight up (NVIS)
• Loss, Feedline, 1.3db (SWR 673)
• Loss, Lowpass L tuner: 9.4db (88W in coil)(2030pf, 32uH)
• Loss total 10.7db
• Power to antenna 8.6w

Conclusions

This looks like a good antenna for 40 and up, as W4RNL indicated. It looks useable on 60 and 80 but not easy to match on those bands. The tuner should be high voltage rated and with wide impedance capability. It should be placed very near the antenna to minimize the length of the feedline. Only low loss balanced line should be considered as other types will have too much loss. Transmissions should be short or QRP as tuner is taking a lot of heat load. This antenna is really too short for 80 meters.

AlanB WB6ZQZ

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CategoryHamRadio