Many, many posts have appeared on this board and other Part 15 boards to the effect that the length of a short conductor between an elevated Part 15 AM transmitter and another conducting path such as a massive wire is defined by such posters to be the entire ground lead length that "counts" in the legal, 3-meter length permitted by 15.219(b).
A few other posts (mostly mine) have shown that this is untrue from the perspective of physics and experience, because without adequate r-f filters, the entire length(s) of all conducting path(s) connected to the transmitter chassis can radiate significantly until they reach a functional r-f ground -- typically, something buried in the earth. Such conducting paths easily can mean that the total radiating length exceeds the 3-meter length permitted by 15.219(b).
To prove this point, following is a cut & paste from an FCC NOUO on this subject, issued in 2010.
Of course people are free to operate their "Part 15" stations as they wish, but hopefully with recognition of the realities and the risks of doing so.
RF
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NOTICE OF UNLICENSED OPERATION
Case Number: EB-10-KC-0023
Document Number: W201032560002
The Kansas City Office received information that an unlicensed broadcast
radio station on 1640 kHz was allegedly operating in Omaha, Nebraska. On
March 24, 2010, agents from this office confirmed by direction finding
techniques that radio signals on frequency 1640 kHz were emanating from
your residence in Omaha, Nebraska. The Commission's records show that no
license was issued for operation of a broadcast station on 1640 kHz at
this location in Omaha, Nebraska.
Radio stations must be licensed by the FCC pursuant to 47 U.S.C. S: 301.
The only exception to this licensing requirement is for certain
transmitters using or operating at a power level or mode of operation that
complies with the standards established in Part 15 of the Commission's
rules, 47 C.F.R. S:S: 15.1 et seq. The field strength of the signal on
frequency 1640 kHz was measured at 73,800 microvolts per meter (uV/m) at
30 meters,[/i] which exceeded the maximum permitted level of 14.6 uV/m at 30
meters for non-licensed devices set out in Section 15.209 of the Rules, 47
C.F.R. S: 15.209. Further, the station's operation did not comply with the
alternative operating requirements for stations operating in the band
510-1705 kHz that are set out in Section 15.219 of the Rules, 47 C.F.R. S:
15.219. Specifically, the agents measured the field strength of 19,700
microvolts per meter (uV/m) at 30 meters with the 20 foot ground wire
detached. This shows that the ground wire was radiating and exceeds the 3
meter combined maximum length of all radiating elements permitted under
Section 15.219(a). Thus, this station is operating in violation of 47
C.F.R. S: 301.
You are hereby warned that operation of radio transmitting equipment
without a valid radio station authorization constitutes a violation of the
Federal laws cited above and could subject the operator to severe
penalties, including, but not limited to, substantial monetary fines, in
rem arrest action against the offending radio equipment, and criminal
sanctions including imprisonment. (see 47 U.S.C. S:S: 401, 501, 503 and
510).
UNLICENSED OPERATION OF THIS RADIO STATION MUST BE DISCONTINUED
IMMEDIATELY.
You have ten (10) days from the date of this notice to respond with any
evidence that you have authority to operate granted by the FCC. Your
response should be sent to the address in the letterhead and reference the
listed case and document number. Under the Privacy Act of 1974, 5 U.S.C.
S: 552a(e)(3), we are informing you that the Commission's staff will use
all relevant material information before it to determine what, if any,
enforcement action is required to ensure your compliance with FCC Rules.
This will include any information that you disclose in your reply.
You may contact this office if you have any questions.
Robert C. McKinney
District Director
A few other posts (mostly mine) have shown that this is untrue from the perspective of physics and experience, because without adequate r-f filters, the entire length(s) of all conducting path(s) connected to the transmitter chassis can radiate significantly until they reach a functional r-f ground -- typically, something buried in the earth. Such conducting paths easily can mean that the total radiating length exceeds the 3-meter length permitted by 15.219(b).
To prove this point, following is a cut & paste from an FCC NOUO on this subject, issued in 2010.
Of course people are free to operate their "Part 15" stations as they wish, but hopefully with recognition of the realities and the risks of doing so.
RF
+ + + +
NOTICE OF UNLICENSED OPERATION
Case Number: EB-10-KC-0023
Document Number: W201032560002
The Kansas City Office received information that an unlicensed broadcast
radio station on 1640 kHz was allegedly operating in Omaha, Nebraska. On
March 24, 2010, agents from this office confirmed by direction finding
techniques that radio signals on frequency 1640 kHz were emanating from
your residence in Omaha, Nebraska. The Commission's records show that no
license was issued for operation of a broadcast station on 1640 kHz at
this location in Omaha, Nebraska.
Radio stations must be licensed by the FCC pursuant to 47 U.S.C. S: 301.
The only exception to this licensing requirement is for certain
transmitters using or operating at a power level or mode of operation that
complies with the standards established in Part 15 of the Commission's
rules, 47 C.F.R. S:S: 15.1 et seq. The field strength of the signal on
frequency 1640 kHz was measured at 73,800 microvolts per meter (uV/m) at
30 meters,[/i] which exceeded the maximum permitted level of 14.6 uV/m at 30
meters for non-licensed devices set out in Section 15.209 of the Rules, 47
C.F.R. S: 15.209. Further, the station's operation did not comply with the
alternative operating requirements for stations operating in the band
510-1705 kHz that are set out in Section 15.219 of the Rules, 47 C.F.R. S:
15.219. Specifically, the agents measured the field strength of 19,700
microvolts per meter (uV/m) at 30 meters with the 20 foot ground wire
detached. This shows that the ground wire was radiating and exceeds the 3
meter combined maximum length of all radiating elements permitted under
Section 15.219(a). Thus, this station is operating in violation of 47
C.F.R. S: 301.
You are hereby warned that operation of radio transmitting equipment
without a valid radio station authorization constitutes a violation of the
Federal laws cited above and could subject the operator to severe
penalties, including, but not limited to, substantial monetary fines, in
rem arrest action against the offending radio equipment, and criminal
sanctions including imprisonment. (see 47 U.S.C. S:S: 401, 501, 503 and
510).
UNLICENSED OPERATION OF THIS RADIO STATION MUST BE DISCONTINUED
IMMEDIATELY.
You have ten (10) days from the date of this notice to respond with any
evidence that you have authority to operate granted by the FCC. Your
response should be sent to the address in the letterhead and reference the
listed case and document number. Under the Privacy Act of 1974, 5 U.S.C.
S: 552a(e)(3), we are informing you that the Commission's staff will use
all relevant material information before it to determine what, if any,
enforcement action is required to ensure your compliance with FCC Rules.
This will include any information that you disclose in your reply.
You may contact this office if you have any questions.
Robert C. McKinney
District Director
