AM Ground System Company

Updated 09/07/2007

Welcome

We have completed several projects since the last update and they may be found on the left hand side bar.

HOWEVER

THIS SITE IS ALWAYS

And some pages may not load correctly or are incomplete. Sorry for the inconvenience but I will try to get them updated and working as soon as possible.

Site Vandalism & Theft On the Rise

With continuing record high copper prices it was inevitable that the "other half" would discovered the value of the copper at our transmitter sites.

We are preparing a white paper concerning site security and many of the problems and ideas we have observed and been advised of.

In Short:

Sites MUST be checked regularly.
Most vandalism and theft does not take place in one visit on one day/night.

Vandalism quickly found and reported tends to be less severe.

The vandals are magnitudes more likely to be located and caught when the damage is found quickly.
Site security MUST be maintained.
Perimeter fencing and gates must be substantial and maintained. Crackheads and tweakers are pretty energetic when attempting to steal something but the harder they have to work for something the less appealing it is.

Site lighting must be implemented and maintained.

Site lighting should be monitored for damage or outages. 100% of the vandalized sites that we have worked on that HAD site lighting, HAD damage to that lighting. Vandalism to lighting has occurred several days before the copper theft attempts in some cases.
General building alarms and "bait" are often effective if kept reliable.

Many more site security ideas and observations will be presented in the aforementioned whitepaper.

Elevated Ground Systems

To elevate or not to elevate... That is the Question!

Research efforts for AM antenna ground systems have been sporadically conducted (no pun intended) over the years. The original 1930's AM antenna and specifically AM ground system research by Dr. George H. Brown has been considered to be the standard for many years. The FCC adopted Dr. Brown's work as it's standard for AM grounding even though it was somewhat limited in scope. Ironically, it was quite accurate by even today's standards

A viable ground system alternative that Dr. Brown did not explore and hence was not readily accepted by the FCC was the elevated type system. An elevated ground system utilizes 6-10 wires suspended above ground for the AM antenna ground plane. The elevated system works differently from a conventional in-ground system but the effect is the same. Current that would be consumed thru ground losses is captured and returned to the antenna feed point.

Elevated ground systems have a definite place in AM radio but not usually for the reasons that most people inquire about them. Some of those reasons are noted below.

An elevated GS uses only 5-10% of the radials needed for an in-ground system. That makes it a LOT cheaper. Right?
Answer: Sorry. But in most cases Wrong. A properly built elevated ground system will be only slightly less expensive to build on a clean dry site. There may only be 6-10 radials but those radials MUST be supported at least 12-15ft above ground level. This requires the use of numerous treated wooden poles and insulators. By the time that we supply and install the electrical portion of the kit (wire, insulators and hardware) and then add in the mechanical portion (poles, anchors, tower base terminations) PLUS installation time and equipment, the cost is usually very comparable to a conventional in ground system.

On the other hand, installing an elevated ground system on a "challenged" site (wet, protected, overgrown, additional use, all of the above, etc) can be substantially cheaper than installing a conventional system on that same challenged site. This is usually due to equipment and time needs as well as legal, regulatory and other costs.

A contractor might be found that would build a cheap, cheap elevated GS but it would probably fail to perform (or continue to perform) as well as a properly designed and constructed installation.
Those elevated ground systems require less space than a normal ground system. Right?
Answer: Wrong. Research over the years has concluded that an elevated radial should be over 90 degrees long (normal ground radials are 90�) to be most efficient. Hence, an elevated GS will require slightly MORE property than a standard GS.
Our transmitter site is in a "bad" part of town. Anything of value will disappear if left overnight. Those elevated ground systems are theft proof because they use copper clad steel wire instead of solid copper wire. Right?
Answer: (repeat after me) Wrong. If anything an elevated GS is more attractive than an in-ground simply due to the wire being visible. it has been widely reported that copper thieves carry magnets to identify non copper wire.

I think that this is giving considerably too much credit to the crackheads and tweakers for their intellectual abilities. Will the thief be much chagrined to find that his nights work will only net about 20% of what he expected? Yep. Will he bring the wire back? Nope. Your ground system will still be GONE. Will he come back after you rebuild. Probably not. Will someone else try it the next night with the same result? Possibly.

The bright side to theft of elevated ground systems is that replacement of the wire is typically easier and less costly than repairs to a conventional in-ground system. Unless they break insulators or cut down poles.