Step 1: Materials and Tools
Base: particle board or plywood, flat, 12 inches by 32 inches, one half to three quarters of an inch thick; edges do not need to be perfectly straight or smooth, nor the corners perfectly square.
Screw Posts: nine 6-32 screws, one and one-half inches long; twenty-seven 6-32 nuts; eighteen number six flat washers.
Drawing paper 12 inches by 32 inches (Optional) You can also draw directly on the base board, but paper will allow greater precision.
Drawing compass(es), having hard, very sharp pencil lead or dividers having very sharp points; capable of drawing arcs up to 7.07 inches (180 mm) radius, such as Dasco Pro, Inc., Giant Circle 12-inch Beam Compass shown in photo.
Pencil having hard, very fine point
Straight edge, such as yardstick, metal version preferred
Ruler, one foot long, divided into tenths of an inch or in millimeters
Drill bit nine sixty-fourths (0.140) inches diameter; another bit about half that diameter for pilot holes
Screwdriver, for 6-32 screw head
Wrenches, two, for 6-32 nut
Medium-width permanent marker
Step 2: Layout
The design of the Gray-Hoverman antenna and its dimensions are protected under license (by others). This information is offered free for personal use, but no commercial exploitation is permitted. This is a link to the color pdf drawing of the antenna that I used for the active element dimensions http://www.user.dccnet.com/jonleblanc/Canada_TV_Stations/Gray-Hoverman/DBGH_VHF_hi_Antenna.pdf. In the final step I provide links within the digitalhome.ca website that provide history, description, performance, variations, and construction examples of the antenna, as well as to the license.
Step 3: Draw Six Five-Inch (127 Mm) Arcs
2. Draw a straight vertical line perfectly perpendicular to the base line and no farther than one inch from the left edge of the board or paper.
3. Adjust the compass to 5.00 inches (127 mm) and, working from the left intersection, mark off six equal spaces along the base line, as shown in the photo. Do not draw dots.
4. Draw a straight vertical line perfectly perpendicular with the base line, at the intersection of the sixth arc.
5. Check the perpendicularity of the two vertical lines by confirming that they are 30.00 inches apart at their top ends.
Step 4: Draw Six 7.07-Inch (180 Mm) Arcs
Step 5: Draw Two 5.41-Inch (137 Mm) Arcs
2. If drawing on paper, tape the paper to the base board and transfer the nine points to the board by poking through with a very fine sharp pin. It is OK to draw a light open circle, at least a quarter inch in diameter, around each of the pin points in the board to make it easier to locate them when drilling.
Step 6: Punch and Drill
2. Drill a pilot hole through the board at one point, using a bit about half the diameter of the nine sixty-fourths (0.140) inch diameter bit, as an aid to centering the drill press in each punch mark.
3. Without moving the board, switch to the nine sixty-fourths (0.140) inch diameter bit and carefully drill through that pilot hole.
4. Repeat to drill the remaining eight holes.
Step 7: Screw It
2. Insert a screw in each hole, with a washer on each side of the board, and snug on a nut at the base of each screw post.
3. Add two more nuts to each screw post, adjust the upper nut so its top edge is one quarter of an inch from the top of its post.
4. Hold the upper nut and tighten the lower nut against it to jam it in place, ensure the quarter inch spacing. These two nuts will never need to be removed.
Step 8: Label the Links
Step 9: G-H Antenna Information Links
2. Antenna Research and Development Forum
3. Photo of mast-mounted outdoor G-H antenna (by others, post #94)
4. License governing the use of the antenna design information