How long is an 80m dipole?
Read more about . . . . Dipole Length Calculations.
| Approximate Lengths for HF Ham Band Dipole Antennas | ||
|---|---|---|
| Band (MHz) | Length (Feet) | Length (metres) |
| 3.5 (80 metres) | 137 | 42.2 |
| 7.0 MHz (40 metres) | 68.5 | 21.1 |
| 10.1 (30 metres) | 47.5 | 14.7 |
How long should be a counterpoise for an end fed antenna?
Length of counterpoise should be approx. 20-30 feet but NOT resonant. If possible, run the counterpoise away from or perpendicular to the antenna wire. You can also use the unun with no counterpoise or ground if your feedline is at least 25+ feet long.
How long is a 80 meter end fed antenna?
The antenna has a limited bandwidth on the 80 meter band because the antenna is shortened for this band. The 10/(15)/20/40/80 End fed Antenna Kit has a total length of about 23 meters. From the feed point first 20.4 meter antenna wire then a coil of approximately 110 uH and then another +/- 2.5 meters wire.
Will a doublet antenna work on a 40 Meter Dipole?
A doublet antenna (dipole), cut for 80 meters, will not work on 40 meters because 7 MHz is an even harmonic multiple of 3.5 MHz. This means that if we try to feed 7 MHz to 3.5 MHz (80 meter) dipole, the 7 MHz current would be at a minimum (null) at the center feed point of the 80-meter dipole.
Is an 80 meter doublet antenna good enough for my roof?
If your main interest is DX, the 80 meter doublet is not a good DX antenna. You should consider a multi-band vertical on that 7th floor roof, if roof is large enough to lay out several quarter-wave radials.
How much line do I need for an 80 Meter Dipole antenna?
Should be okay; for an 80 meter dipole I’d shoot for 32-34 feet of ladder line (1/8th-wave on 80); this will form a quarter-wave impedance inverter on 40 to bring down the very high impedance on 40 where the antenna is 2 half-waves fed at the voltage antinode.
What is the largest doublet antenna?
80m doublets appear to be the largest commonly used. Perhaps the reason for this, certainly in the UK, is due to the small areas most people have to erect a long antenna. Another possibility is that because of the size of a 160m doublet it becomes hard to tune on most amateur bands. I really don’t the reason, but those are my theories.