[TowerTalk] antennas and towers near broadcast stations

[RICHARD SOLOMON]

Wait a minute, let me get my lawyer out of the closet.
 
73, Dick, W1KSZ> Date: Sat, 14 Feb 2009 17:16:36 -0500> From: jimjarvis at optonline.net> To: towertalk at contesting.com> Subject: Re: [TowerTalk] antennas and towers near broadcast stations> > > Bottom post... see below:> > (edited for space...)> Message: 6> Date: Fri, 13 Feb 2009 20:47:25 -0600> From: "Its from Onion" <aredandgold at msn.com> Subject: [TowerTalk] > Antennas and towers near broadcast stations> > The FCC has without much notice in Amateur circles passed was: > "quietly snuck," a poor choice of words, a Rule that will affect non- > broadcast radio licensees including Radio Amateurs.> excerpt:> > Quote:> ?1.30002 Tower construction or modification near AM stations.> (a) Construction near a nondirectional AM station. Proponents > of construction or significant modification of a tower which is > within one wavelength of the AM station, and is taller than 60 > electrical degrees at the> AM frequency, must notify the AM station at least 30 days in > advance. The proponent shall examine the potential impact of the > construction or modification as described in paragraph (c). If the > construction or> modification would distort the radiation pattern by more than > 2 dB, the licensee shall be responsible for the installation and > maintenance of any detuning apparatus necessary to restore proper > operation of the> nondirectional antenna.> (b) Construction near a directional AM station. Proponents of > the construction or significant modification of a tower which is > within the lesser of 10 wavelengths or 3 kilometers of the AM > station, and is taller than 36 electrical degrees at the AM > frequency, must notify the AM station at least 30 days in advance.> The proponent shall examine the potential impact of the > construction or modification as described in paragraph (c). If the > construction or modification would result in radiation in excess of > the AM station's licensed standard pattern or augmented standard > pattern values, the licensee shall be responsible for the > installation and maintenance of any detuning apparatus necessary to > restore proper operation of the directional antenna.> (c) Proponents of construction or significant modification of > a tower within the distances defined in (a) and (b) herein of an AM > station shall examine the potential effects thereof using a moment > method analysis. The moment method analysis shall consist of a model > of the AM antenna together with the> potential reradiating tower in a lossless environment. The > model shall employ a simplified version of the methodology specified > in ? 73.151(c) of this chapter. The AM antenna elements may be > modeled as a Federal Communications Commission FCC 08-228 series of > thin wires driven to produce the required radiation pattern, without > any requirement for measurement of tower impedances.> (d) A significant modification of a tower in the immediate > vicinity of an AM station is defined as follows:> (1) Any change that would alter the structure's physical > height by 5 electrical degrees or more at the AM frequency.> (2) The addition of one or more antennas or a transmission > line to a tower that has been detuned or base insulated.> (e) The addition or modification of an antenna or antenna > supporting structure on a building shall not be considered significant.> (f) With respect to an AM station that was authorized pursuant > to a directional proof of performance based on field strength > measurements, the proponent of the tower construction or modification > may, in lieu of the study described in paragraph (c), demonstrate > through measurements taken before and after construction that field > strength values at the monitoring points do not exceed the licensed > values. In the event that the pre-construction monitoring point > values exceed the licensed values, the proponent may> demonstrate that post-construction monitoring point values do > not exceed the pre-construction values.> Alternatively, the AM station may file for authority to > increase the relevant monitoring point value after performing a > partial proof of performance in accordance with ? 73.154 to establish > that the licensed radiation limit on the applicable radial is not > exceeded.> (g) Tower construction or modification that falls outside the > criteria described in the preceding paragraphs is presumed to have no > significant effect on an AM station. In some instances, however, an > AM station may be affected by tower construction notwithstanding the > criteria set forth above. In such cases, an AM station may submit a > showing that its operation has been affected by tower construction or > alteration. If necessary, the Commission shall direct the tower > proponent to install and maintain any detuning apparatus necessary to > restore proper operation of the AM antenna.> > LINK<http://fjallfoss.fcc.gov/edocs_public/attachmatch/FCC-08-228A1.pdf>> > A vertical resonant at 1.8 MHz is 81 degrees tall at 1.6 MHz and > would be if not detuned at the BC frequency forbidden within 2 miles > (approx) (or 10 wavelengths at its frequency if less) of a > directional AM station. An 80 meter vertical falls to it as well, as > well as many shorter towers according to their electrical length.> > Considering the impact the unnoticed Part 73 action has had in > Amateur circles, a reconsideration could be in order if only to > accept our comments.> -0-> > N2EA Comments: This is perfectly reasonable, on its face. > Commercial interests bear the responsibility of assuring> that their construction... towers or power lines, for example... do > not impact the pattern of a directional array AM station.> The cost of re-certifying a directional array... repeating the proof, > is something on the order of $20,000, in today's dollars,> before you add in the consulting engineer's fees. Been there, done > that, as they say. 4 times, in fact.> > I had a 4 tower AM station go out of licensed Field Strength > parameters, and had to operate on waivers, for> over a year, until we identified a high tension line at 2 miles > distant as the offending construction. Lawsuit> followed. It was $100k legal fees, out of pocket, until the utility > in question lost, paid up, and detuned their towers.> Then, we had to repeat the proof of performance, which entailed > almost $20k in labor, plus a consulting engineer's> fee of 14k.> > Like the idea that amateurs should be exempt from stupid driving > while distracted by our radios, we are not exempt> from causing inadvertent harm to commercial operations by our > construction. Much as we might like it to be otherwise.> Thoughtful consideration is in order, with all we do. (Like > climbing safely!)> > I think the real concern here is cell towers, not us, just to be > practical. Oh, and just to crank a few numbers,> a wavelength at 1 MHz is 936'. 10 wavelengths is 1.8 miles. At > 1.5Mhz, that's 1.2 miles. Odds of us affecting> them at that distance are quite small. But why should we be exempt, > if we cause harm?> > If we make a vertical resonant on our operating frequency, it is, de- > facto, non-resonant at the broadcast freq.> i.e. decoupled. And we shouldn't have to worry.> > Unreasonable rule making? I don't think so.> > N2EA> Jim Jarvis, MBA, President> The Morse Group, LLC> www.themorsegroup.net> Leadership and Supervisory Development * Strategic Planning * > Corporate Coaching> > > > _______________________________________________> > > > _______________________________________________> TowerTalk mailing list> TowerTalk at contesting.com> http://lists.contesting.com/mailman/listinfo/towertalk