Antenna Placement

The Antenna Placement demo asks the genetic algorithm to put six antennas on a 2D map so that they reach as much of the open area as possible without spending budget on overlapping coverage. A few rectangular obstacles block signal in straight lines, so a "good" layout is one that wraps around them.

The problem¶

Every antenna projects a circular coverage zone of a fixed radius. Anywhere inside that circle is reachable, unless an obstacle sits on the line between the antenna and the point. Coverage is good. Two or three antennas reaching the same point at the same time is wasted budget. The genetic algorithm needs to balance the two.

How a run looks¶

Click Start. Fifteen layouts are evaluated immediately. The leader, the layout with the highest fitness this generation, fades in across about a second and a half so you can see the shape of its coverage. The other fourteen layouts sit on the canvas as faint outlines so you can compare. A pale tint highlights every grid cell that the leader's antennas reach; a bolder tint marks cells that two or more antennas cover (the overlap penalty).

The platform then evolves the population. Four elites carry over unchanged, eleven children come from tournament-of-three winners with uniform crossover and small per-coordinate random nudges. The next round arrives a moment later and the leader looks slightly cleaner.

Within roughly ten generations on a typical map, the antennas spread out enough that the overlap tint mostly disappears and the coverage tint pushes into the corners. The history strip under the canvas keeps the best layout from every generation.

Fitness¶

The browser samples a 100 by 60 grid of points across the map. For each open point it counts how many antennas reach it. Points inside an obstacle do not count. Fitness is coverage_pct - 0.25 * overlap_pct, where coverage_pct is the share of open points reached by at least one antenna and overlap_pct is the share reached by two or more. Higher is better.

What the achievement rewards¶

The first time a best-of-generation layout scores at least 0.80, the Signal everywhere achievement unlocks for signed-in users. That bar is reachable on most maps within fifteen generations or so; tougher obstacle layouts can take longer.

For more on how the demos catalog works, see What the demos do.