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Knife edge limits for § 15.221 Operation in the band 525-1705 kHz.

Posted: Sat Nov 03, 2018 9:52 am
by spareparts
The Nonprofit I volunteer at has a potential grant to purchase a TR6000 Model 15.73 and ANXX Antenna. Our attorney is drafting a letter to the FCC to verify that our educational status qualifies us to operate under § 15.221

Before I ask to spend non-grant money on hiring a professional (PE or GROL) engineer to do the measurements, I wanted to make sure I understand the regulatory.

§ 15.221 (2) states: At the perimeter of the campus, the field strength of any emissions, including those within the frequency band 525-1705 kHz, shall not exceed the general radiated emission in § 15.209.

Our campus is irregular in shape, crosses streets and involves a river. How would you determine / calculate the perimeter?

SP

Re: Knife edge limits for § 15.221 Operation in the band 525-1705 kHz.

Posted: Sat Nov 03, 2018 10:52 pm
by Deep Thought
The perimeter is the outermost property line. As a practical matter, unless you are going to deploy multiple transmitters the limit will be imposed at the point on that perimeter closest to the antenna.

Re: Knife edge limits for § 15.221 Operation in the band 525-1705 kHz.

Posted: Mon Nov 05, 2018 4:41 am
by R. Fry
An unlicensed AM transmit system exactly meeting FCC §15.219 most likely would permit much higher field intensities at the campus perimeter than using §15.209. See below:

Note: Some of the assumed 85 mW of output power is dissipated in the radial ground system. Those effects are included in the mileages shown in the table.)

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