A thorough discussion of Ham Radio Station Protection Techniques.
For technical questions about
Ham Radio Station Protection and PolyPhaser Protectors,please call
Comm-Omni International at 800-543-8790
Proper lightning protection for a ham radio station can involve more variables than any other type of radio site. The antenna location will establish the grounding requirements, while the station location will drive the protection requirements.
The primary rule for surviving a lightning strike is still the same no matter which of the many possible variations you have: all equipment elements must be connected to a single, low impedance ground system. This includes the antenna, the antenna support (pole, tower, etc.), and all of your station’ s input and output protectors. (I/O’ s:
antenna, power, telephone, rotor, etc.).
Let’ s examine the significant elements of a good grounding and protection scheme to help you construct an installation that will survive a direct lightning strike.
We begin with choosing the antenna location. This and the antenna type will dictate the size and location of the earth system needed to disperse the strike’ s energy. The sooner the ground system is able to spread out the energy, the better the chances of preventing it from traveling to your equipment. Almost 90% of strikes will be
a deposit of electrons which, due to like charge, repel and spread out. The antenna ground system provides the interface to the earth body. As we will see later on, the ground system is formed by a set of ground rods interconnected below grade with bare radials.
Also fundamental to a good protection scheme is the creation of a single point ground within the ham shack. This single point ground is used to mount all of the protectors and to provide a ground for all of the equipment chassis. This interior single point ground is connected to an external ground system (composed of radials with
ground rods) with a low impedance copper strap. The tower ground system and the single point ground system must be interconnected. This interconnection should be below grade and with a bare low inductance conductor.
Your coax shield must not be the only interconnection between these ground systems.
Every conductor has measurable inductance. Similarly, ground conductors exhibit normal inductance before they go below grade. Once in the ground, the inductance of a bare conductor is shunted by the earth’ s conductivity.
If the soil at the grounding location is not very conductive, three things can be done to help the situation. First, increase the surface area of the conductor, decreasing its normal inductance. Second, dope the soil to increase its conductivity shunting the inductance of the in-ground bare conductors. Third, install additional bare radial