Something I noticed whichall hams and us recognize because of extremely short antenna restrictions isthe significant advantage of using loading systems, mostly coils.
A sharp increasein range couldbehad with a 50′ backyard or rooftop antenna with scaled up loading coils. If youcan shove enough into it to get as little as 100w erp, you shouldbe able to cover thecommunity of license for a construction permit application in myarea…enoughtocover most all of the occupied islands, 80-100%.
Another solution involving a magnetic as opposed to electric antenna might beproposed as well, eh? Much easier to load, but would look weird…probably require more testing than we couldafford to be approved.
Carl Blaresays
Magnetic Antennas?
Don’t stop talking, say more!
Magnetic antennas… have we ever talked about them before? What is a “magnetic antenna?”
The students are sitting here waiting to learn.
Richsays
What is a “magnetic antenna?”
Please check this thread, especially posts 1 and 4 there.
I will stick with your groundless antenna over on another thread.
Carl Blaresays
Reviewing
The opening link posted above from rock95seven is worth the time to visit the FCC Notice of Proposed Rulemaking for a thourough reading.
The section noted by Ken Norris is especially interesting, to those of us who talk about short antennas and rooftop installs, and I clipped it here..
“MMTC “proposes that the Commission replace ‘minimum efficiency’ for AM antennas with ‘minimum radiation’ in mV/m, thereby allowing AM stations to use very short antennas and enjoy more flexibility in site selection including rooftop installations.”98 Under MMTC’s formulation, an AM broadcaster would only be required to show that the broadcast station produces a certain minimum level of radiation.99 According to MMTC, “provided that the minimum radiation is achieved, efficiency levels are immaterial.”100 MMTC contends that the minimum efficiency standard originated in the 1920s when electric power was in short supply but land was abundantly available.101 Now, MMTC argues, “the relative availability of land and electric power are exactly reversed,” and the Commission “must reevaluate the regulation to conform to its public interest obligation.”102 MMTC believes that the current rule works a hardship on lower-frequency stations because “lower frequencies are having trouble meeting the minimum efficiency standard due to the large size of the antenna required to meet the standard.”103 Replacing the minimum efficiency standard with a minimum radiation standard, according to MMTC,” – End Clip from FCC NOPRM
ANOTHER THING linked within the FCC Text is this link fully describing the state of AM noise interference…
The FCC defines the efficiency of an AM broadcast monopole as the inverse distance field intensity it produces at a horizontal distance of 1 km for 1 kW of applied power. This value depends on the physical height and cross-section dimensions of the monopole, the operating frequency, the loss in the matching network at the antenna feedpoint, and the loss in the system r-f ground.
The FCC specifies certain minimum fields (or efficiencies) for different classes of AM broadcast stations. For example those efficiencies are lower for low-power, local stations (Class C) than for high-power (Class A) stations intended to serve large geographic areas.
The efficiency needed by a Class A station cannot be provided by a 1/4-wave monopole using 120 x 1/4-wave buried burials, however a monopole less than 1/4-wave tall using fewer/shorter buried radials may produce the efficiency needed by a Class C or D station.
MMTC apparently is assuming some other definition of efficiency applies when they link radiator efficiency to a-c power consumption.
Here is an informative clip from further along in that FCC Docket.
In the Matter of Revitalization of the AM Radio Service, MB Docket No. 13-249
From Paragraph 41 (bold font added):
“While MMTC’s proposal calls for a “minimum radiation” standard expressed in mV/m, as noted above our current rules already provide such a standard as an alternative to the minimum antenna heights set forth therein. Section 73.189(b)(1) of the Rules states that good engineering practice requires an AM applicant either “to install a new antenna system or to make changes in the existing antenna system which will meet the minimum height requirements, or submit evidence that the present antenna system meets the minimum requirements with respect to field strength, before favorable consideration will be given thereto.” Thus, for Class B, Class D, and Alaskan Class A AM stations, an antenna must either meet the minimum height requirements set forth in curves A, B, and C of Figure 7 of Section 73.190,109 or must provide a minimum effective field strength of 282 mV/m for 1 kilowatt at 1 kilometer from the transmitter. In other words, our rules already provide for non-standard antennas, as long as they meet minimum field strength standards. It is unclear how the current rules differ from MMTC’s proposed “minimum radiation” standard which, again, is not described by MMTC in any detail.“
Carl Blaresays
Uncertainty Factor
Rich has pointed up a significant uncertainty factor in the proposed rule changes regarding smaller antennas, and I believe there is another elephant in the room that has not been mentioned at all…
While the stated intention of making changes is to improve the odds of success for AM radio stations, it is assumed that technical changes alone will tip the scales in their favor, and that would be naive at best.
Nor is it made clear why certain alterings of day night operation, power level adjustements and looser antenna requirements will actually do any more than make AM operation somewhat simpler.
As Neil and others have often said, AM has lost most of its audience as a result of poor programming. Many of us would not listen to most of them whether or not the signal was “improved” or “on at night.”
FCC Proposals
I’m about 1/2 way thru it….
Something I noticed whichall hams and us recognize because of extremely short antenna restrictions isthe significant advantage of using loading systems, mostly coils.
A sharp increasein range couldbehad with a 50′ backyard or rooftop antenna with scaled up loading coils. If youcan shove enough into it to get as little as 100w erp, you shouldbe able to cover thecommunity of license for a construction permit application in myarea…enoughtocover most all of the occupied islands, 80-100%.
Another solution involving a magnetic as opposed to electric antenna might beproposed as well, eh? Much easier to load, but would look weird…probably require more testing than we couldafford to be approved.
Magnetic Antennas?
Don’t stop talking, say more!
Magnetic antennas… have we ever talked about them before? What is a “magnetic antenna?”
The students are sitting here waiting to learn.
What is a “magnetic antenna?”
Please check this thread, especially posts 1 and 4 there.
http://radiodiscussions.com/showthread.php?634097-Loop-Transmit-Antennas-for-Part-15-AM
Class Dismissed
Thank you for explaining magnetic antenna.
I will stick with your groundless antenna over on another thread.
Reviewing
The opening link posted above from rock95seven is worth the time to visit the FCC Notice of Proposed Rulemaking for a thourough reading.
The section noted by Ken Norris is especially interesting, to those of us who talk about short antennas and rooftop installs, and I clipped it here..
“MMTC “proposes that the Commission replace ‘minimum efficiency’ for AM antennas with ‘minimum radiation’ in mV/m, thereby allowing AM stations to use very short antennas and enjoy more flexibility in site selection including rooftop installations.”98 Under MMTC’s formulation, an AM broadcaster would only be required to show that the broadcast station produces a certain minimum level
of radiation.99 According to MMTC, “provided that the minimum radiation is achieved, efficiency levels are immaterial.”100 MMTC contends that the minimum efficiency standard originated in the 1920s when electric power was in short supply but land was abundantly available.101 Now, MMTC argues, “the relative availability of land and electric power are exactly reversed,” and the Commission “must reevaluate the regulation to conform to its public interest obligation.”102 MMTC believes that the current rule works a hardship on lower-frequency stations because “lower frequencies are having trouble meeting the minimum efficiency standard due to the large size of the antenna required to meet the standard.”103
Replacing the minimum efficiency standard with a minimum radiation standard, according to MMTC,” – End Clip from FCC NOPRM
ANOTHER THING linked within the FCC Text is this link fully describing the state of AM noise interference…
http://radiojayallen.com/combatting-am-and-sw-interference/
FCC Definition of Antenna Efficiency
The FCC defines the efficiency of an AM broadcast monopole as the inverse distance field intensity it produces at a horizontal distance of 1 km for 1 kW of applied power. This value depends on the physical height and cross-section dimensions of the monopole, the operating frequency, the loss in the matching network at the antenna feedpoint, and the loss in the system r-f ground.
The FCC specifies certain minimum fields (or efficiencies) for different classes of AM broadcast stations. For example those efficiencies are lower for low-power, local stations (Class C) than for high-power (Class A) stations intended to serve large geographic areas.
The efficiency needed by a Class A station cannot be provided by a 1/4-wave monopole using 120 x 1/4-wave buried burials, however a monopole less than 1/4-wave tall using fewer/shorter buried radials may produce the efficiency needed by a Class C or D station.
MMTC apparently is assuming some other definition of efficiency applies when they link radiator efficiency to a-c power consumption.
Here is an informative clip from further along in that FCC Docket.
In the Matter of Revitalization of the AM Radio Service,
MB Docket No. 13-249
From Paragraph 41 (bold font added):
“While MMTC’s proposal calls for a “minimum radiation” standard expressed in mV/m, as noted above our current rules already provide such a standard as an alternative to the minimum antenna heights set forth therein. Section 73.189(b)(1) of the Rules states that good engineering practice requires an AM applicant either “to install a new antenna system or to make changes in the existing antenna system which will meet the minimum height requirements, or submit evidence that the present antenna system meets the minimum requirements with respect to field strength, before favorable consideration will be given thereto.” Thus, for Class B, Class D, and Alaskan Class A AM stations, an antenna must either meet the minimum height requirements set forth in curves A, B, and C of Figure 7 of Section
73.190,109 or must provide a minimum effective field strength of 282 mV/m for 1 kilowatt at 1 kilometer from the transmitter. In other words, our rules already provide for non-standard antennas, as long as they meet minimum field strength standards. It is unclear how the current rules differ from MMTC’s proposed “minimum radiation” standard which, again, is not described by MMTC in any detail.“
Uncertainty Factor
Rich has pointed up a significant uncertainty factor in the proposed rule changes regarding smaller antennas, and I believe there is another elephant in the room that has not been mentioned at all…
While the stated intention of making changes is to improve the odds of success for AM radio stations, it is assumed that technical changes alone will tip the scales in their favor, and that would be naive at best.
Nor is it made clear why certain alterings of day night operation, power level adjustements and looser antenna requirements will actually do any more than make AM operation somewhat simpler.
As Neil and others have often said, AM has lost most of its audience as a result of poor programming. Many of us would not listen to most of them whether or not the signal was “improved” or “on at night.”