TABLE OF CONTENTS In order to perform EW modeling, it is necessary to understand the basic elements of radio propagation. This chapter covers the so-called one-way link equation, the radar range equation, and several important link equations derived from them.
Figure 4.1 is a basic communication link. Its purpose is to take information from the location of the transmitter and deliver it to the location of the receiver. A link is defined as a transmitter, a receiver, two antennas, and everything that happens between the two antennas or something that acts like that set of elements. Figure 4.2 shows the signal strength as a signal passes through the link. The path through the link is not to scale; it focuses on what happens in each of the elements from the source of the information to its delivery.
The transmitter outputs a radio frequency signal at some signal strength the transmitted power (P T). It is defined in some units derived from watts; in EW it is most common to state the transmitted power in dBm.
Next, the signal passes through the transmitting antenna, which has a gain (in dB). In the diagram, this gain is shown as positive, and we will always add the gain to the transmitter power, even though the antenna gain may be positive or negative in dB. It is important to note that the antenna gain in this chart is the gain in the direction...
