Regarding the "ground" issue we at RangeMaster feel that after reading the Part 15 rules and discussing with officials at the FCC that all ground does not have to be dirt, for several reasons:

What is ground isn't specified in Part 15, just the antenna and ground LEAD length.

It is just impractical for all Part 15 transmitters to be located on the dirt. In most major metro areas, close access to the dirt just isn't practical. For many reasons (vandalism, traffic, local regulations, safety, ect.) It is reasonable to allow the installer some flexibility in location for the Part 15 transmitter installation. The most out of the way location is typically on the roof.

The most important reason we suggest people be able to ground their transmitters to a ground other then the dirt is lightning protection. The lightning protection provided by lightning protection circuitry in our transmitter is critical to protect life and property and must be ground properly to provide such protection. What we don't like to hear (and do often) is customers in apartment buildings who do not have their transmitters grounded at all and have had lightning damage because they are afraid of the 3 meter rule, they didn't follow our grounding instructions because they have been told by someone that it would violate the 3 meter rule. This is an unfortunate situation.

In our discussions with the FCC massive metal that is connected to the dirt, such as a water pipe, can serve as an acceptable ground. I have been told that the FCC generally won't interfere with a site engineers decision (if the site engineer decides to call a water pipe ground) unless the decision seems outlandish. We feel a large piece of wire, coming up from the dirt can also be called ground at the top tip. As long as the wire takes a direct path straight down to the dirt, this is best for lightning protection. We have had this set-up pass FCC field inspection many times. We don't feel that in most cases, a properly designed ground system will add significantly to the overall radiation of the system, however if your system requires it, we stock an RF filter that you can place in series with the ground terminal of the transmitter (needs to be placed physically right at the transmitter ground terminal to be effective) that will suppress RF radiation from the ground system. Just let us know when ordering and we will include the filter.

See the ground page