A while back I posted this article about some of the differences I’ve noticed while studying for a UK Amateur Radio license compared to the US license rules. I’ve just come across a few more about geographic restrictions, which are probably amongst the most curious of the license rules.
US Geographic Restrictions
In the US, the Part 97 rules define a couple of geographic areas where you’re not allowed to transmit.
(m) In the 70 cm band:
(1) No amateur station shall transmit from north of Line A in the 420-430 MHz segment. See §97.3(a) for the definition of Line A.
And defines Line A as:
(30) Line A. Begins at Aberdeen, WA, running by great circle arc to the intersection of 48° N, 120° W, thence along parallel 48° N, to the intersection of 95° W, thence by great circle arc through the southernmost point of Duluth, MN, thence by great circle arc to 45° N, 85° W, thence southward along meridian 85° W, to its intersection with parallel 41° N, thence along parallel 41° N, to its intersection with meridian 82° W, thence by great circle arc through the southernmost point of Bangor, ME, thence by great circle arc through the southernmost point of Searsport, ME, at which point it terminates.
The reason for this restriction is that Canada does not allow 70cm Amateur Radio usage between 420-430Mhz and so this corridor along the North US border with Canada and between Alaska and Canada is to prevent interference with other primary users of 420-430MHz.
There are a couple of other location specific restrictions stated in Part 97 for US operators:
(2) Amateur stations transmitting in the 420-430 MHz segment must not cause harmful interference to, and must accept interference from, stations authorized by the FCC in the land mobile service within 80.5 km of Buffalo, Cleveland, and Detroit. See §2.106, footnote US230 for specific frequencies and coordinates.
Since 70cm band usage is on a secondary user basis, restrictions are to prevent interference with primary users in these areas.
The US Part 97 rules also mention restrictions for the National Radio Quiet Zone in Virginia – this location contains the Green Bank Observatory and a Naval Research Station. Part 97.203 mentions restrictions to automated beacon stations in this area.
Another interesting restriction on 70cms is the power restriction to 50w in locations near to particular military bases. Having lived in the Sacramento Valley area, this 70cms restriction is known to the local clubs and operators as a measure to avoid interference within 150 miles of the PAVE PAWS radar at Beale AFB.
UK Geographic Restrictions
I’ve only come across these similar UK restriction so far, stated on the license bandplan:
431 to 432 MHz is not available within 100 km radius of Charing Cross, London
As UK 70cm usage is as a secondary user, this is again to avoid interference to primary users in this band.
Beacons may be established for DF competitions except within 50 km of TA 012869 (Scarborough)
If anyone knows what is specifically at this location leave a comment below, although this RSGB page and map may give some clues since Menwith Hill is also mentioned here as another area with restrictions.