Link budget can help to predict equipment weight, size, prime power requirements, technical risk and cost. Link budget is one of the system manager’s useful document.

The larger the antenna aperture the larger is the resulting signal power density in the desired direction. The ratio of effective aperture to physical aperture is the antenna’s efficiency.

There are two primary causes for the degradation of error performance. They are loss in signal to noise ratio and the second is signal distortion caused by intersymbol interference.

Due to the decrease in electric field strength there will be a decrease in signal strength as a function of distance. This is called as space loss.

The reciprocity theorem states that for a given antenna and carrier wavelength the transmitting and receiving gain are identical.

The link analysis and its output, the link budget consists of calculations and tabulations of useful signal power and interfering noise power at the receiver.

Mechanism contributing to a reduction in efficiency is called as amplitude tapering, spillover, edge diffraction, blockage, scattering, re-radiation and dissipative loss.

When a local oscillator is used in signal mixing, phase fluctuations and jitter adds phase noise to the signal.

Antennas are used as transducer that converts electronic signals to electromagnetic fields and vice versa. They are also used to focus the electromagnetic energy in the desired direction.

An effective radiated power with respect to an isotropic radiator EIRP can be defined as the product of transmitted power and the gain of the transmitting antenna.