Robots can be controlled via several means. Tele-operated, or human control allows a person to take control of all the robot’s movement. ©Emil Decker, 2009

The transmitter, or remote is usually abbreviated as TX. Physical movements of the controller are converted to radio waves carrying electronic signaling data to the receiver. ©Emil Decker, 2009

Receivers, abbreviated RX, listen to specific frequencies or channels for these instructions. They are then converted into electrical impulses to make the robot move. ©Emil Decker, 2009

Radio systems are tuned to a specific radio frequency via a crystal. Matched sets, with one in the transmitter and one in the receiver, are used. ©Emil Decker, 2009

An antenna is a transducer designed to transmit or receive electromagnetic waves. Transmitter antennas convert electrical current into electromagnetic waves, and then receiver antennas collect those waves, and turn them back into into electrical current. ©Emil Decker, 2009

Thomas Edison experimented with antennas, as did Tesla and others, but the origin of the word antenna relative to wireless apparatus has been attributed to Guglielmo Marconi. ©Emil Decker, 2009

In 1913, the Eiffel Tower was used an antenna to communicate with the United States Naval Observatory in Arlington, Virginia. ©Emil Decker, 2009

An electromagnetic wave is an electric field that travels away from a source such as an antenna. A traveling electric field has an associated magnetic field, making up an electromagnetic wave. These waves take the shape known as a sinusoidal wave. EM waves vary with space (position) and time, and are periodic. This simply means it repeats itself every so many (time) units in what we call a wavelength. The frequency (f) is simply the number of complete cycles the wave completes (viewed as a function of time) in one second or in what is known as a "Hertz". ©Emil Decker, 2009

The formula for frequency can be written as. ©Emil Decker, 2009 f= 1 T

Frequency is simply a calculation of how fast the wave is oscillating. All EM waves travel at the speed of light. The faster it oscillates the shorter the wavelength. A longer wavelength would produce a slower frequency. ©Emil Decker, 2009

One cycle One second Hertz Amplitude

The set of all frequencies is referred to as the " Radio Spectrum". Companies desiring to use a frequency band have to pay a large sum of money to get access to a given part of the spectrum. ©Emil Decker, 2009

There are three important characteristics of antennas. They are types, sizes, and shapes. Passive antennas are the most common type. They are constructed of a piece of metal, wire, or similar conductive material. Telescoping antennas are very prominent in toys and home electronics. ©Emil Decker, 2009

Antenna shapes and sizes are dependent on 3 characteristics. Antenna size, direction of the radiated electromagnetic wave, and the power with which the antenna must transmit. The size of an antenna is inversely proportional to the wavelength of the signal it is designed to transmit or receive. In other words, the higher frequencies use smaller antennas. ©Emil Decker, 2009

RF waves spread away from the source antenna in the same way that a circular wave created by throwing a stone into a pond gets wider and wider and moves away from the point where the stone hit the water. ©Emil Decker, 2009

Because of this, both antennas should be as parallel as possible. Pointing the TX antenna at a RX receiver does not improve the signal. Nor does having the RX antenna, often a flexible wire, coiled or wrapped up. Antenna sleeves are usually provided with kits to help orient the RX antenna to correspond to the TX; primarily in a somewhat vertical position. ©Emil Decker, 2009