02 — Antenna placement (R6.2 family, 7 sub-ticks)

The 9-tick R6.2 family productised R6's forward model into a working CLI-shaped placement search. Each script answers one axis of the placement question.

Scripts (in development order)

Script	Thread	Axis	Headline
r6_2_antenna_placement.py	R6.2	2D single-pair	Optimal placement is 93× better than median random; corner-to-corner diagonal
r6_2_1_3d_placement.py	R6.2.1	3D single-pair	Ceiling-only mounting fails (0% coverage) — Fresnel envelope sits at ceiling, never reaches floor targets
r6_2_2_multistatic_placement.py	R6.2.2	2D N-anchor	Knee at N=5 anchors for typical bedroom (96.8% body-zone coverage)
r6_2_2_1_3d_multistatic.py	R6.2.2.1	3D N-anchor	2D knee disappears in 3D — only 49% at N=5 with body zones
r6_2_3_chest_centric.py	R6.2.3	2D chest-centric	+27 pp coverage gain when targeting chest specifically (vital-signs cog)
r6_2_4_3d_chest_multistatic.py	R6.2.4	3D chest-centric	Recovers 3D shortfall — 77% at N=5, 82% at N=6 chest-centric
r6_2_5_multi_subject.py	R6.2.5	Multi-subject union	100% coverage for 1-4 occupants at N=5 chest-centric

Decision matrix (final ADR-113 output)

Cog category	Dimension	Zone mode	Occupants	N	Heights	Coverage
Vital signs	2D	chest	1-4	5	walls 0.8/1.5 m	100%
Vital signs	3D	chest	1-4	6	walls 0.8/1.5 (NO ceiling)	82%
Pose estimation	2D	body	1-2	5	walls mixed	97%
Pose estimation	3D	body	1-2	7-8	mixed L/M/H	65%+
Person count	2D	body	1-4	4	walls mixed	86%

Counter-intuitive findings

1. Longer links cover more space. Fresnel envelope width = √(d·λ)/2 grows with d.
2. Ceiling-only fails entirely (R6.2.1) — both anchors at 2.5 m put envelope at ceiling height, target zones below are missed.
3. 2D N=5 knee doesn't hold in 3D (R6.2.2.1) — 3D ellipsoids are thin slabs, not 2D rectangles.
4. Anchor heights should match target zone heights (R6.2.4) — chest-centric uses low+mid, NOT ceiling.
5. Chest-centric beats body-centric for vital signs by +27 pp (R6.2.3).

See also

• Architectural decision: docs/adr/ADR-113-multistatic-placement-strategy.md
• Research notes: docs/research/sota-2026-05-22/R6_2*.md
• Composes with: 01-physics-floor/ (forward model), 06-structure-detection/ (PABS uses placement coverage)