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 MIL-HDBK-419A
1.3.3.3 Waveguide Installation and Grounding. Waveguide between the antenna and the associated
transmit/receive equipment should be grounded in the following manner.
a.
Each waveguide shall be bonded to the down conductor of the air terminal at the top near the
antenna and also at the bottom near the vertical to horizontal transition point. The waveguide shall also be
bonded to the antenna tower at the same points as well as at an intermediate point if the tower exceeds
60 meters (200 feet).
b.
All waveguide support structures shall be bonded to the tower. The waveguides and supporting
structure shall be bonded together at the waveguide entry plate and connected to the earth electrode
subsystem.
All waveguides, conduit or piping entering a building shall be bonded to the waveguide entry plate,
c.
then to the earth electrode subsystem (see Figures 1-26 thru 1-31). For waveguide penetrations of a shielded
enclosure or entry plate see Volume I, Section 10.4.2.4.
Rigid waveguides within 1.8 meters (6 feet) of each other should be bonded together through the
d.
entry plate or by means of a crimp type lug fastened under the waveguide flange bolts and No. 6 AWG wire.
The bond shall be extended to the bus at the waveguide entry point and connected to the earth electrode
subsystem.
Determine location of ground strap position as shown in Figure 1-28A and remove waveguide jacket.
e.
The ground strap is made from a piece of waveguide as detailed in Figures 1-29 and 1-30. Clean mating
surfaces (waveguide and strap) with solvent or cleaning fluid.
Wrap the strap with No. 14 AWG copper wire (for 8 GHz waveguide as shown Figure 1-28A). For
f.
4 GHz waveguide, use No. 10 AWG solid copper wire. Use adjustable stainless steel clamps as required to
secure the strap. Tighten screw until the clamp grips firmly. Excessive tightening could damage the waveguide
and impair the electrical characteristics. Weatherproof with Scotch Guard or equivalent and tape.
An alternate method of securing the strap to the waveguide is to use wrap-around heat shrink to
g.
cover the bond and to maintain weatherproofing. Solder one end of a solid copper wire (#10 for 4 GHz and #14
for 8 GHz waveguide) to one end of corrugated portion of the ground strap. Align the corrugated section of the
ground strap with the exposed section of the waveguide (see Figure 1-28B). Tightly wrap the wire around the
ground strap and waveguide and solder the end of the wire to the ground strap for securing purposes. Apply the
wrap-around heat shrink around the waveguide and heat according to the manufacturer's instructions.
Remove all sharp and rough edges on ground strap.
h.
An alternate method for grounding waveguide is also shown on Figure 1-26.
i.
1-42
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