Statistical resolution limit (SRL) — closest two targets tellable apart vs SNR · hover a point (session 014z DF model)
SIDE-LOOKING monopulse for a fixed-wing (Ranger-1600 class): ONE routed FR4 strip (61×342 mm, 41 g vs 62 g solid) flat on the wing-top/deck on 4× M3 nylon posts (25 mm, nyloc) — two FR4 Moxon rectangles at 240 mm (0.73λ) along the FLIGHT AXIS, beam +x ALONG THE WING, Δ-null plane abeam: orbit/flypast DF; the rotating-monopulse finder chain applies with the heading sweep · BUILD SPEC (PML, moxon-family mesh): dim_scale 0.815 / gap C 10.2 mm (element 95.5×41.1 mm) → res 915.0 MHz, S11 −20.5 dB, Zin 46.8+8.6j — direct 50 Ω, no matching network · CLEAN PAIR: Σ 8.9 dBi · Σ F/B 13.8 dB · HPBW 36° · Δ null −34.9 dB · η 91.2% · OPTIMAL CUTOUTS, FDTD-settled: FR4 kept only at two full-length rails + 4 mm trace aprons + per-element coax SPINES (element-centreline transverse-E nulls) + centre web — 6 windows routed out, −35% mass; the windows UNLOAD the arms, so the published solid-board gap (8.8 mm) under-couples — re-balancing C 8.8→10.2 mm recovers the Moxon null; after re-balance the routed board BEATS solid on the same-mesh A/B: Σ −0.2 dB · F/B +3.1 dB · η +5.9 pts · Δ null equal · 41 vs 62 g · MOUNTED (full-wave PML with the airframe conductors: Ø8 CF spar ALONG the beam 40 mm under the board — crosses the elements at 90°, 2× CF tail rods PARALLEL under the aft element, LiPo, pusher motor, harness; runs converged to −40 dB): Σ 7.3 dBi at the horizon (beam tilts +30° up, peak 8.1 dBi — the broad Moxon H-plane makes the tilt cost only ~1.3 dB; banking toward the target in an orbit rolls it back), Σ F/B 11.6 dB, Δ null −16 dB @ −2° (the battery-vs-motor fore/aft asymmetry shifts the null 2° nose-ward — a DF calibration constant, like the measured template's −2.6° squint; −16 dB ≈ the −15 dB operational background floor that the interference study showed is the real limit), S11@915 −21.5 dB — mounting detunes +18–22 MHz, the 25 mm standoff is the trim knob · FINDER ON THE MOUNTED PATTERNS (100 rdg/°, 1 dB steps, 3 dB noise, bg −15 dB): bearing accuracy 0.13° (1σ) · two-emitter resolution 5.0° · Σ HPBW 32° — airframe scatter costs ~nothing vs the clean cards (0.10°/5.3°) · MOUNT: posts on the rails at the element centrelines (E-nulls); plate modes ≥~330 Hz, nylon sway <65 Hz → the 133–200 Hz prop band stays clear; coax UNDER the board on the spines, EQUAL length, 5-bead ferrite choke at each feed (centre→aft arm pad, shield→fwd arm pad), rat-race Σ/Δ hybrid below deck (see the rat-race card) · FLIGHT COST (biquad_flight model): ~0.10 N @ 12 m/s + ~100 g installed → 77→66 min endurance (−14%; the biquad plate build costs −26% on the same model) · mesh protocol: build spec + clean absolutes on the eps-scaled moxon-family mesh; cutout A/B + mounted deltas on a snapped air-bulk λ/20 twin (clean-centred at 0.83/12.5), each vs its own same-mesh baseline — cross-policy scatter ±10 MHz / ±2 dB F/B; near-coincident mesh lines snapped <0.35 mm (the unsnapped PML airframe runs went late-time unstable) · cutting DXF
⬗ stack-up: FR4 1.6 mm (εr 4.3) · 1 oz Cu (35 µm) · single top layer, ONE routed strip 61×342 mm (41 g, 6 windows) · 2× Moxon Σ/Δ @ 240 mm (0.73λ) along the flight axis · 4× M3 nylon posts 25 mm · Ranger-1600-class conductor set