As a receiver, aerial aperture is the diameter of a circle constructed broadside to incoming radiation where all radiation passing within the circle is absorbed by the antenna. Adding a reflective dish can increase the energy collecting area of the aerial without further narrowing the beam angle. In the case of white noise the amplitude of the exciting signal can be very low and a radio receiver used as the detector. A more efficient variation of this is the half-wave dipole, which radiates with high efficiency when the signal wavelength is twice the electrical length of the aerial.

In all directions the sent signal has the same power. Because of the way that electromagnetic fields propagate through space at the speed of light, an accelerating electrical charge creates electromagnetic radiation.

The SWR meter works by minimizing the reflected wave from the aerial back to the transmitter, which is minimal when the aerial is balanced. Wavelengths get so short at these frequencies that it is not possible anymore to transmit using a pole antenna and transmit in all directions. If this is not possible, compensating inductors or capacitors can instead be added to the aerial to cancel its reactance as far as the source is concerned. So how do you know which one to go for?.

The design criteria for receiving and transmitting differ slightly, but generally an aerial can receive and transmit equally well. Complex impedance of an antenna is related to the electrical length of the aerial at the wavelength in use. Often a dip is also used as a practical reference as the isotropic source cannot be realised in practice, but it has 2.1 dB gain over an isotropic source.

This region is called the antenna blind cone or null. The polarization of an antenna or orientation of the radio wave is determined by the electric field or E-plane. Antennas can be made resonant on harmonic frequencies with lengths that are fractions of the target wavelength.

A trailing wire aerial is used by submarines when submerged. However, when the current stops, these fields collapse, returning energy to the power supply. Antennas used for transmission have a maximum power rating, beyond which heating, arcing or sparking may occur in the components, which may cause them to be damaged or destroyed.

Airlanes need for radar, GPS, radio, beacons, and voice radio. All of these parameters are expressed in terms of a transmission aerial, but are identically applicable to a receiving antenna, due to reciprocity. Unlike nearly all other in this list, this aerial detects the magnetic component of the electromagnetic wave. Since this is the simplest practical antenna, it is also used as reference model for other gain with respect to a dipole is labeled as dBd. Most gains are measured with reference to an isotropic radiator, and are rated in dBi.

With the development of wireless routers that come with a WiFi aerial, work using the computer can be done without the need to connect any wires. Variations of the quad include the delta loop aerial which uses a triangle instead of a square, requiring fewer supports for large wavelength. Also, aiming it a place where people in the house can only use it.