When ELECTROMAGNETIC WAVES ENCOUNTER a circuit that is not smaller than they are, strange things can happen. As the frequency into the “microwave” region above a billion hertz the unit of frequency the wavelength gets close to the size of a circuit board the simple idea of a circuit begins to fade away. Conductors start to parts of the wave that are out of step with each other, so that voltage and currents no longer add up as expected Passive components misbehave , with resistors turning into inductors and in inductors into capacitors. Active components can stop working altogether Electronic at these frequencies is almost a different subject Components and circuit have to be made smaller or the way waves travel allowed for both. Even electrons can be too sluggish for microwaves can carry information They keep to straight paths which is useful for linking cities Unlike longer waves they can penetrate the Earth’s outer atmosphere to allow communication with space