This simulator explores a parabolic reflector with a focal feed. Watch equal-length ray paths leave the dish parallel to its axis by the parabola's geometric property, then scan the dish past a fixed receiver and compare boresight gain, effective aperture, beamwidth and the pointing loss that results from aiming error.
• A real-time 3D scene of a parabolic reflector with radial ribs, a focal feed horn on support struts, animated feed-to-dish-to-output ray paths, an azimuth drive and pedestal, a fixed receiver with an alignment indicator, and a gain/alignment instrument, with show/hide toggles for the ray animation and reflective surface. • Ten experiment controls: frequency (3,000–12,000 MHz), reflector diameter (0.5–2 m), aperture efficiency (0.3–0.85), focal-length/diameter ratio (0.35–0.65), accepted transmit power (1–100 W), far-field receiver distance (500–2,000 m), mean pointing error (−15° to 15°), a ±3° pointing-sweep toggle, and show/hide toggles for the ray animation and reflective surface. • Live metrics: boresight gain in dBi and as a linear ratio, effective aperture, full half-power beamwidth, first-null angle, the 2D²/λ far-field criterion, current pointing error, directional power relative to boresight, pointing loss in dB, boresight EIRP, receiver power density and unity-gain reference received power. • A Curves & measurements tab with two live charts (gain metrics), the full parabolic-aperture gain/beamwidth equations, and snapshot measurement readouts. • An Experiments tab with four guided fixtures (double the aperture diameter, scan across the main lobe, compare efficiency, follow equal-length rays) and a Model verification bench, plus a timestamped event log and a copyable trial report. • A Learn & assess tab with four guided lessons, a knowledge-check quiz with reset, and a written model-scope statement with a technical-background reference link.
The parabola has a useful equal-path property: the distance from focus to the reflector surface plus the distance from that point onward to a common output plane is always the same, regardless of which point on the dish a ray strikes. Geometric rays therefore leave the dish parallel to the axis, consistent with an outgoing planar wavefront. Effective aperture and gain follow Ae = ηA and G = 4πAe/λ² = η(πD/λ)² — doubling the reflector diameter quadruples gain at fixed frequency and efficiency, about a 6.02 dB increase.
A uniformly illuminated circular aperture produces an Airy power pattern; a larger diameter-to-wavelength ratio narrows the main lobe, which means a small pointing error can move the receiver from the main lobe peak into a null or a sidelobe. Efficiency scales gain as a single multiplying factor in this model but leaves the normalized pattern shape unchanged — a real antenna's feed taper, aperture blockage, spillover and surface errors can change both gain and pattern shape together, effects this simplified model does not include.
This is an ideal circular-aperture far-field approximation for a parabolic reflector with uniform illumination and an independently specified scalar aperture efficiency. It excludes rear radiation, feed blockage, illumination taper, sidelobe calibration, conductor loss and a near-field solve. All offered receiver distances exceed the standard 2D²/λ far-field bound.
By 4×. Gain scales with aperture area, which scales with the square of diameter, so a doubled diameter quadruples linear gain (about a 6.02 dB increase).
No. Gain concentrates the same accepted transmit power into a narrower directional beam rather than creating additional energy — it increases intensity in one direction at the expense of others.
No, not in this model. Efficiency is treated as a single scalar factor that scales overall gain, while the normalized pattern shape stays the uniform-aperture Airy pattern regardless of the efficiency setting.
A larger dish-diameter-to-wavelength ratio produces a narrower main lobe. Since pointing loss depends on how far off-axis the receiver falls relative to the beamwidth, a narrower beam means the same angular pointing error causes a much larger power loss.