Statistical resolution limit (SRL) — closest two targets tellable apart vs SNR · hover a point (session 014z DF model)
9.8 dBi D (PML) · ~9.7 dBi realized @ η 97% · F/B 17.5 dB · S11 −28 dB @ 915.0 · BW(−10 dB) 88 MHz · side 75 mm — FR4 loading shrink 0.90 measured by sweep (settles the 0.80-vs-0.92 dispute) · same 46 mm spacing/standoffs as the wired build · copper faces the reflector: coax pads solder directly, no vias · braid collar to plate + ferrite choke · element board 232×126, nylon M3 standoffs · CM check (explicit coax): bare −27.5 dB / collar bond −61 dB / λ/4 sleeve −49 dB @915 — the reflector bond IS the balun workhorse · WIND→FEM (OpenFOAM RANS + CalculiX): Cd 1.23, 59 N @30 m/s (133 N @45) · 1.6 mm plate on a 40×40 mm centre clamp bows 11 mm at the corners @30 m/s → Δspacing ≈2.2 mm → ΔR +3.7 Ω, Δf −0.7 MHz — match holds (linear FEM, conservative) · σvM 27 MPa (≈16× FR4 margin) · @45 m/s corners flap ~25 mm — use a full-width mast plate / 3 mm substrate for permanent outdoor mounts · FUSELAGE MOUNT (fixed-wing, vertical, flow along the 350 mm side): cruise drag only 0.6-0.7 N @30 m/s · sideslip turns it into a fin: |Fy| 20 N @β=10° / 27 N @β=15°, mount moment 3.4 N·m · plate bows 5.1 mm @β=15° → ΔR +1.7 Ω — RF-benign · beam points sideways; reflector shields the airframe · F/worst-3D-lobe 16.0 dB
⬗ stack-up: element: FR4 1.6 mm (εr 4.3) · 1 oz Cu, single layer · reflector: copper-clad FR4 350×250 mm · 46 mm air gap