A Giant 40-Meter Wire Beam

by MD0MDI
A Giant 40-Meter Wire Beam - figure 6

A Giant 40 Meter Wire Beam

This is one of those antennas that came out of a what-if? session with Ted Hart, W5QJR some time ago. We were talking about what kind of antennas would give some real gain on the lower frequencies and he suggested a collinear array made out of 5/8 wavelength elements with the bottom elements 1/2 wavelength above ground and the top elements 1 wavelength high. Then, by making a four-element array with the second pair of elements besides the first, this should give an antenna with some gain. Exactly how much we weren’t sure. After modelling the antenna using AO6.5 I found out there was 13.54 dBd gain at 17 degrees elevation. This came from a combination of the elements being phased correctly and the 5/8 wave elements each had some gain to contribute due to the total gain of this type of antenna.

Figure 1 is the horizontal diagram of this antenna, and the beamwidth is exceptionally narrow. Approximately 20 degrees is what seems to show up on the pattern and is a very narrow pattern, both fore and aft, since this is a bi-directional antenna. Figure 2 is the vertical pattern, and this indicated the maximum is at 17° which is ideal for DX work on any band. Figure 3 is the basic construction of the antenna, less supporting structures.

A Giant 40 Meter Wire Beam - figure 1
A Giant 40 Meter Wire Beam - figure 1
A Giant 40 Meter Wire Beam - figure 2
A Giant 40 Meter Wire Beam - figure 2
A Giant 40 Meter Wire Beam - figure 3
A Giant 40 Meter Wire Beam - figure 3

Figure 4 is of the antenna showing the current distribution and magnitude on the elements. Figure 5 is the 3D pattern viewed from the side and slightly to the left of a right angle to the centre of the antenna and up about 30 degrees. Figure 6 is directly above the centre and is also a 3D representation. Figure 7 is a possible construction idea.

A Giant 40 Meter Wire Beam - figure 4
A Giant 40 Meter Wire Beam - figure 4
A Giant 40 Meter Wire Beam - figure 5
A Giant 40 Meter Wire Beam - figure 5
A Giant 40 Meter Wire Beam - figure 6
A Giant 40 Meter Wire Beam - figure 6
A Giant 40 Meter Wire Beam - figure 7
A Giant 40 Meter Wire Beam - figure 7

TABLE OF DIMENSIONS

  • Element lengths: 161.54 Dipole construction, fed in centre.
  • Element Heights: lower 4 elements 65 ft. Upper 4 130 ft.

PHASING

  • Bottom element left: 0°, bottom right 180°.
  • Top element left: 0°, top right 180°.

Feed point Impedance at Each Element

  • Element 1: 341-388Ω
  • Element 2: 341-388Ω
  • Element 3: 341-388Ω
  • Element 4: 341-388Ω

Again, this is one huge antenna being 130+ feet high and close to 400 feet across. If you can put one up, I can guarantee you will be king of the hill in any part of the 40 meter band that you want to operate.

Originally posted on the AntennaX Online Magazine by Richard Morrow, K5CNF

Last Updated : 25th February 2024

error: Content is protected !!
@2014-2024 - All Right Reserved. ManxDesigns, James Sawle, MD0MDI.

This website uses cookies to improve your experience. We'll assume you're ok with this, but you can opt-out if you wish. Accept Read More

free counters