The antenna field of view is the measure of a solid angle in which most of the field power is concentrated. It is inversely related to antenna gain.

Antenna gain increases with a decrease in wavelength increase in frequency and increase in effective area.

Increasing either the signal frequency or antenna size results in narrower beam width.

The path loss is wavelength(frequency) dependent. The path loss is proportional to the square of the distance between the transmitter and receiver as seen above and also to the square of the frequency in use.

The free space path loss can be expressed in terms of either the wavelength or the frequency.

Thermal noise occurs due to the thermal motion of electrons in all conductors. It occurs due to lossy coupling between an antenna and the receiver.

With analog receivers, the noise bandwidth seen by the demodulator is usually greater than the signal bandwidth.

Link availability is the measure of long-term link utility stated on an average annual basis for a given geographical location, the link availability measures the percentage of time the link can be closed.

For a fixed link margin, visibility is inversely proportional to the required availability, and for a fixed availability, visibility increases monotonically with margin.

The stop and wait ARQ needs a half-duplex system since the transmitter needs ACK for each transmission.

The ARQ procedure called continuous ARQ with pullback requires a full-duplex connection.