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Assumptions and notes
- Gmax is the primary input. Extra inputs appear only when a selected pattern requires them (φ₀, Bmin, D, LN), pre-filled with defaults derived from Gmax.
- Scroll the mouse wheel over the chart to zoom both axes in and out around the cursor; double-click to reset (±180° and y-axis refitted to the curves in view). Until the first zoom, the y-axis auto-fits the visible curves; gridline and label density increase as you zoom.
- Drag a JPG/PNG onto the chart (Cartesian mode) to overlay it for comparison — e.g. a scanned or screenshot mask to check against the computed envelope. The image is pinned to the φ/dBi axes (tracks zoom and pan), starts at 50% opacity (adjustable), and can be moved by dragging its body or resized by its corner and edge handles for independent width/height. Remove it with the button by the opacity slider.
- D/λ is obtained from Gmax for every pattern by the single AP8 / RR Annex III relation
D/λ = 10^((Gmax−7.7)/20)(implicit η ≈ 0.6). No separate efficiency input is used, so Gmax is the only aperture parameter. Where a Recommendation defines D/λ via Gmax = 10 log(η(πD/λ)²) but leaves η open (e.g. RS.1813, S.1855), this AP8 relation is the assumed conversion; it coincides with RS.1813's own stated default of η = 60%. - φ₀ default uses the Appendix 30 relation
φ₀ = 2(λ/D)·√(3/0.0025) = 69.28 λ/Dwith D/λ from the AP8 relation above; editable while a φ₀-dependent pattern is selected. S.1528 uses ψb = φ₀/2. - D default (AP30 WRC-97 earth station, fixed 12.1 GHz) is derived from Gmax via the AP8 relation; editable. Plan reference antenna: 0.60 m, Gmax = 35.5 dBi.
- Co-polar patterns only; cross-polar components defined for some patterns (AP30 and AP30A) are not plotted. Patterns are symmetric in |φ|; the −180 to +180° axis mirrors the 0 to 180° definition. Appendix 30, 30A and 30B family patterns are drawn with broken lines; all others solid.
- Space station patterns (except S.1528 and RS.1813, which define their own far and back lobe floors) are floored at 0 dBi, per the antenna pattern library absolute-gain convention.
- S.672-4 with Ls = −15 dB (APSREC413V01): a = 2.236 by continuity (a = 2·√(−Ls/12)); consistent with a = 1.83 (Ls = −10) and a = 2.58 (Ls = −20). b = 6.32 for all.
- S.1855: circular aperture assumed (θ = 0), so the 7°–9.2° segment is a flat 7.9 dBi and the 3 sin²θ envelope terms vanish; Deq/λ from Gmax by the AP8 relation. S.1528 (recommends 1.2, APSREC409V01): z = 1, LN = −15 dB (BR standard; other values selectable), G = max(G1…G5) with far side lobe 0 dBi and back lobe 0.25·Gmax over 90°–180°.
- S.465-6 and S.1855 define envelopes only for φ ≥ φmin; the main lobe is extended with the Appendix 8 style parabola and G₁ plateau, matching the library convention for S.465-5 and S.580.
- Recommendation 580: S.580-6 shares its formula with the current Appendix 30B reference pattern (single library entry APEREC015V01). The obsolete S.580-2 and S.580-5 patterns are not on the current standard-pattern list and are not included.
- Validity warnings (for example AP8 Gmax > 9.3 dB, AP7 D/λ ≥ 35, M.694 within 19.7 to 24.8 dBi, M.1091 within 12 to 18 dBi, BO.1900 D/λ ≥ 32, S.1855 D/λ ≥ 15, SA.509 D/λ ≥ 100) are shown next to each pattern; curves are still plotted outside these ranges.
- Sources: the antenna pattern library reference manual (APL-UM-001) and the pattern documents on the ITU-R antenna patterns software page; Recommendations S.465-6, S.1855, BO.1900, M.1091, SA.509-3, RS.1813-1, S.672-4 and S.1528 for the post-2007 additions.