Applies where the beam is a radio-frequency carrier.
Everything in this annex is excluded from the core by one test: if a quantity’s units, or the document governing it, differ between RF and optical, it belongs in an annex. Everything that survives that test — the session lifecycle, token semantics, abort semantics, ramp semantics, the metering model, frames and units — stays in the core and is shared with any future physical layer.
[R-RF-001] A segment claiming the RF annex SHALL declare centre_GHz,
occupied_bandwidth_Hz, polarisation, and — where a national regime uses one — an
emission designator.
[R-RF-002] Transmit aperture dimensions, illumination taper and the resulting
peak-to-mean factor SHALL be declared, with peakToMeanBasis per [R-A-011].
[R-RF-010] PFD SHALL be expressed in dB(W/m²) with a mandatory refBandwidthHz.
[R-RF-011] PFD SHALL be screened against ITU Radio Regulations Article 21 §21.16
using the applicability discipline of [R-A-001].
Note on why this matters more here than elsewhere. Article 21’s limits are spectral — so many dB(W/m²) in 4 kHz or 1 MHz. A communications downlink spreads its power over megahertz, so only a sliver falls in any reference bandwidth. A power beam is as close to a pure carrier as makes no difference, so effectively the entire flux counts. An implementer who screens a power beam as though it were a communications signal will understate by orders of magnitude.
[R-RF-020] The abstract pointing reference of [R-S-030] SHALL be bound to a pilot signal transmitted from the receiving segment.
[R-RF-021] The pilot SHALL be authenticated by a per-session spreading code or an equivalent rolling-code scheme, and the segment SHALL declare the scheme, the code length and the re-key interval.
[R-RF-022] corridorHalfAngleDeg SHALL be declared. It SHOULD be no larger than the
angle the receiving aperture subtends at the minimum operational slant range.
Worked example: a 2 km aperture at 547 km slant range subtends 3.66 mrad = 0.21°. A ±0.2° corridor is therefore approximately “on the aperture” for a LEO delivery. At GEO the same aperture subtends 0.0032°, so the corridor is far coarser than the pointing requirement and catches only gross failures — see the limitation stated in §5.6.
[R-RF-030] A segment using a phased array SHALL declare its element spacing and the maximum scan angle, and SHALL declare the geometry and power flux-density of any grating lobes over the full scan range.
[R-RF-031] Grating lobes SHALL be screened under §7 exactly as the main beam is, including against the keep-out volume of [R-S-024].
This is the requirement most likely to be missed, and the arithmetic is short. A periodic array produces grating lobes when
d/λ ≥ 1 / (1 + sin θ_scan)
At 5.8 GHz, λ = 51.7 mm, so a ±30° scan requires element spacing d ≤ 34.5 mm. A kilometre-scale aperture is enormously cheaper to build with sparser spacing — and sparser spacing produces full-intensity replicas of the main beam landing kilometres from the aperture, on ground that was never assessed and lies outside the keep-out volume. The lobe is not a sidelobe; it is a second main beam.
The formula is standard array theory and this document is confident in it. This document is not confident that anyone in this industry is currently publishing this number, which is why it is a
SHALL.
[R-RF-040] The defocused pattern produced by the abort action of [R-S-043] SHALL be declared and screened, per [R-S-044].
[R-RF-050] Where a rate profile, a mask or an expected efficiency depends on propagation, the segment SHALL declare which models were used, by reference.
Commonly applicable: ITU-R P.525 (free-space), P.676 (gaseous attenuation), P.618 (Earth-space including rain), P.837 (rain rate), P.838 (rain specific attenuation), P.839 (rain height). This specification names these as declarable references and does not implement or endorse any of them; the edition in force at the time of declaration is the implementer’s responsibility.
[R-RF-051] A declared model reference SHALL carry the edition.
[R-RF-060] Human exposure SHALL be assessed on an incident power-density basis
against ICNIRP 2020 or IEEE C95.1-2019 as declared, and localExposureBasis SHALL
be declared per [R-A-013].
Below 6 GHz, ICNIRP’s local-exposure restriction is on specific absorption rate, which a power-density screening does not address. A 5.8 GHz system is below that boundary.
[R-RF-070] A segment SHALL declare harmonic and spurious emission levels, and the coordination undertaken with incumbent services in the band.
[R-RF-071] Where the illuminated area or any grating lobe intersects airspace, the segment SHALL declare the avionics electromagnetic-compatibility threshold used and the coordination performed with the aviation authority.