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[quote:05a44000d5=”12vman”]Let’s imagine a 6 meter high “Mount” made with whatever (Tower, Pipe) that is “Grounded” to the earth by whatever means.[/quote:05a44000d5]
A Part 15 AM antenna as defined in the Rules is a vertical radiator somewhat less than 3 meters long, its connecting wire to the r-f output connector of the Part 15 AM tx, and the “ground lead,” if used. The Rules say that the sum of those lengths cannot exceed 3 meters.
The Rules do not define what constitutes a “ground lead,” or what constitutes ground. This is where a lot of confusion exists.
From a classic r-f system analysis viewpoint, a ground lead must include all conductors that lead from the r-f ground connection of the tx (normally its chassis) to a connecting point on/at the surface of the Earth.
Such conductors can consist of one or more of the following:
– a dedicated wire (insulated or uninsulated) leading from the tx chassis to a ground rod, ground screen, ground radials, cold water pipe, etc.
– a short, small gauge wire connected to the tx chassis, leading to a longer, larger gauge wire connecting to/at physical Earth. Both wires are part of the “ground lead.”
– a short, small gauge wire connected to the tx chassis, leading to a grounded, metallic tower. Both the wire and the tower length are part of the “ground lead.”
– a path through the shields of cables carrying program audio to the Part 15 tx.
– a path through the power supply connections and circuits for the Part 15 tx.
So the electronic reality is that a 6-meter-high mounting structure with a Part 15 AM tx and a ~ 3-meter radiator on top of it, and having one or more conductive paths of any kind leading from the tx chassis to physical Earth does not, in fact, meet the Rules for Part 15 AM station antenna systems.
Please don’t shoot the messenger ❗