Interactives#
Every interactive widget in the course, grouped by the module that introduces it. Open one on its own for the whole screen, or go to its lesson for the reasoning around it.
Four Cuts, Four Antennas#
The same four pattern cuts, E-plane and H-plane in co-pol and cross-pol, on a dipole, a small loop, a patch, and a horn. The antenna view shows what each cut means; the chamber view shows how a turntable and a source horn take it. Lesson 9 uses the dipole; this is the full tool.
Module 1: Foundations of Electromagnetics and Antennas#
The same wave is a ripple in space and in time (L2). Plane wave — freeze time / freeze space. Open · Lesson
The same wave in 3-D: two fields at right angles (L2). Plane wave in 3-D — E, H, and the direction of power flow. Open · Lesson
The forward and reflected waves add to a standing wave (L2). VSWR standing wave. Open · Lesson
Comparing gain patterns (L2). Polar gain patterns. Open · Lesson
HPBW, FNBW, and SLL move with aperture size (L2). Rectilinear pattern features. Open · Lesson
Effective aperture vs gain and frequency (L2). Effective aperture vs gain and frequency. Open · Lesson
From a line to an ellipse to a circle (L3). Polarization playground. Open · Lesson
The E-vector traces a helix as the wave propagates (L3). Circular polarization helix. Open · Lesson
Reflection, VSWR and mismatch loss (L4). Feed-line match explorer. Open · Lesson
Power factor, in the field (L5). E, H and the instantaneous power flow versus time, as a function of kr. Open · Lesson
Interactive — the three terms and their crossover (L5). Near-field term crossover. Open · Lesson
Interactive — field-region explorer (L5). Field-region explorer. Open · Lesson
Two Sources in Space (L6). The field around a line source, with the observer direction and the far-field pattern. Open · Lesson
The Integral as a Picture (L6). The radiation integral as a coherent phasor sum. Open · Lesson
The Transform and Its Window (L6). The current, its transform, and the visible window. Open · Lesson
Current In, Pattern Out (L6). Line-source current distribution and its far-field pattern. Open · Lesson
Module 2: Antenna Types, Simulation, and Measurement#
Resonance on the Smith Chart (L7). Smith chart showing how a dipole’s input impedance moves as its length changes, with constant-VSWR circles. Open · Lesson
The Dipole Explorer (L7). Dipole explorer: current, pattern, beamwidth, directivity and feed-point impedance against dipole length. Open · Lesson
Convergence (L8). Method-of-moments dipole: solved segment currents against the assumed sinusoid, the feed voltage and current that set the input impedance, and impedance versus segment count. Open · Lesson
The Nulls Fill First (L9). Quadratic phase error from a finite range length, and the pattern it produces compared with the true far-field pattern. Open · Lesson
Four Cuts of One Dipole (L9). A half-wave dipole in 3-D with its pattern, the cut plane, and a probe horn: choose E-plane or H-plane and co-pol or cross-pol, or set the dipole mount and horn polarization as on a chamber turntable. Open · Lesson
Rehearse the Chart First (L10). An antenna resonance shown as an S11 dip in dB and as a Smith-chart locus, with linked marker, impedance, VSWR, and VSWR-2 bandwidth readouts. Open · Lesson
How Much of Your Pattern Is Real (L11). A true radiation pattern compared with the same pattern measured through a receiver with a finite noise floor. Open · Lesson
Height Above Ground (L12). An antenna over a perfect ground plane, its image, and the resulting upper-half-space pattern. Open · Lesson
The Patch: A Half-Wave Line Open at Both Ends (L13). Animated side view of a patch: a wave launched at one end reflects from both open ends and builds a standing wave, with the fringing fields at the ends and their horizontal parts. Open · Lesson
The Patch Designer (L13). Rectangular patch designer: the patch to scale with its feed point, VSWR against frequency, and the two-slot pattern. Open · Lesson
Three Knobs on a Dish (L14). Dish gain, beamwidth, and effective area versus diameter in wavelengths, with the Ruze surface-error penalty. Open · Lesson
Dish and Feed (L14). Dish and feed: the rim angle, edge taper, spillover, and taper efficiency as the dish depth and the feed pattern change. Open · Lesson
Switch On a Yagi (L14). A Yagi switched on: the driven element’s wave spreads out, each parasitic element starts radiating when that wave reaches it, and probes in front and behind record the field against time. Open · Lesson
Two-Element Yagi (L14). Two-element Yagi: phasor sums toward the front and back, and the resulting pattern, as the reflector’s spacing, phase, and amplitude change. Open · Lesson
Module 3: Arrays and ADALM-PHASER Beamforming#
Illumination and Length (L15). Aperture illumination and the far-field pattern it produces. Open · Lesson
Phasor Chain Explorer (L16). Phasor chain: the element phasors added tip to tail for a chosen scan angle, beside the array factor in decibels with a marker at that angle. Open · Lesson
From Two Patterns to One (L16). Two elements, far apart and close together: the field map around the pair and its far-field power pattern, with one element alone, the two powers added, and the two fields added. Open · Lesson
Array Factor Builder (L16). Array factor builder: pattern in dB versus scan angle for N elements at spacing d over lambda, with an optional cosine element factor. Open · Lesson
Visible Region Explorer (L16). Visible region: the array factor against psi with the window real angles reach, and the same pattern against scan angle, for adjustable N, spacing, and steer angle. Open · Lesson
The Measured Sweep (L16). Array factor against a simulated measured sweep, with the steer grid and the noise floor on a toggle. Open · Lesson
Calibration Explorer (L17). Animated calibration of the eight-element array: gain trims to the weakest element, the pair phase sweeps with an argmax or curve-fit estimator, and the pattern before and after. Open · Lesson
Signal Chain Explorer (L17). Interactive block diagram of the PHASER receive chain with a tunable HB100 source. Open · Lesson
Time Alignment (L18). A plane wave crossing the eight-element array, the commanded delays that align it, and the two ADAR1000 sums. Open · Lesson
Receive Signal Path (L18). The receive chain: each element’s signal through its phase shifter and gain stage, the two ADAR1000 sums, and the total, with an optional second source the same delays reject. Open · Lesson
Phase Swings the Fringes (L18). Two elements with a phase setting on one: the field map and far-field pattern as the phase sweeps and the beam swings. Open · Lesson
Phase Ramp and Beam (L18). Steered pattern and per-element phase ramp for the 8-element course array. Open · Lesson
The Sweep, Step by Step (L18). The beam-sweep trace built one phase step at a time: the beam swinging past the HB100, the eight element signals summed, and each step’s power plotted at the angle it steers to. Open · Lesson
Predicted Sweep (L18). Predicted beam-sweep trace and element phases for the PHASER array. Open · Lesson
The Crossing Angle (L19). A direction-finding fix: drag two to four kits around a keep-out circle, or along a firing line, with a hidden source, and watch the least-squares fix, its error ellipse, and each bearing’s residual. Open · Lesson
No Kit? No Problem. (L19). Fox hunt simulator: a taped firing line with five station marks and numbered boxes downrange. Take a reference shot, then ten readings of Angle and Peak Gain at each station, copy them for the notebook; I reveal the live box. Open · Lesson
Beamwidth Explorer (L20). Uniform linear array pattern with half-power beamwidth, nulls, first-null beamwidth and directivity. Open · Lesson
Ideal Versus Measured (L20). Ideal array factor and measured sweep at 8, 4, and 2 active elements. Open · Lesson
Element Times Array (L21). Element factor times array factor for the eight-element course array. Open · Lesson
The Walk Paints as You Go (L21). Simulated hand-walk pattern measurement: a source walks an arc around a fixed beam while the level-versus-time trace paints below. Open · Lesson
The Measured Sweep for Each Preset (L22). Measured beam sweep for the PHASER taper presets, with element gains, HPBW, peak drop and taper efficiency. Open · Lesson
Tapers on the Array (L22). Element amplitudes, pattern, sidelobe level, beamwidth, taper efficiency and peak drop for uniform, Hann, Chebyshev, and cosine-on-pedestal tapers on the eight-element PHASER array, with optional rounding to 1%. Open · Lesson
Three Departures on the Course Array (L23). Grating lobes, beam squint and phase quantization on the 8-element course array. Open · Lesson
What MVDR Chooses (L24). Two-channel MVDR beamformer against an interferer. Open · Lesson
Null Steering on the PHASER (L24). Null steering on the 8-element PHASER array: pattern, element weights, and null depth. Open · Lesson
Module 4: Radar Fundamentals and FMCW#
Radar Equation Explorer (L25). Radar equation explorer: received power, noise floor, SNR, and maximum range versus range for the PHASER. Open · Lesson
Folded Range and Aliased Speed (L26). Range-velocity tradeoff: the unambiguous range and velocity windows a PRF sets, a target’s true range and closing speed, and what the radar reports. Open · Lesson
Threshold Explorer (L27). Detection threshold against the noise and target probability densities, with the operating point on the Pd versus Pfa curve. Open · Lesson
FMCW Explorer (L28). FMCW explorer: the beat signal over one chirp and its range spectrum, for chosen range, bandwidth, chirp length, second target, and window. Open · Lesson
Range-Doppler Explorer (L29). Range-Doppler map of leakage, a wall, and a moving hand, with chirp count, chirp sync, and MTI, beside the canceller’s gain against velocity. Open · Lesson
CFAR Explorer (L30). CFAR threshold over a range profile with clutter and five targets, with guard, reference, bias and method controls. Open · Lesson
Window Explorer (L31). Slow-time spectrogram of a walker, a fan, a spinner, or a waving hand, with the window length set from 8 to 512 chirps. Open · Lesson