11.8 LOOKING AHEAD
In Chapters 9 and 10, we examined transmitters, receivers, and guided transmission media. In this chapter, we analyzed how electromagnetic waves propagate once radiated into space. Between these domains lies a critical interface: the antenna.
An antenna performs the transformation between guided electromagnetic energy—confined within conductors or waveguides—and radiated energy that propagates freely through space. It determines:
- How efficiently power is transferred from transmitter to free space,
- How incoming waves are captured and delivered to the receiver,
- The direction in which energy is concentrated,
- The polarization and spatial distribution of the radiated field.
Without antennas, there is no practical means of launching or receiving propagating electromagnetic waves.
Chapter 12 therefore examines antennas as electromagnetic radiators and collectors. We will explore radiation mechanisms, current distributions, polarization, radiation patterns, directivity, gain, impedance, and bandwidth. We will see how antenna geometry controls field distribution and how antenna performance influences link budgets, coverage, and interference.
If Chapter 11 explained how waves travel once in space, Chapter 12 explains how they get there—and how they are captured at the far end.
With that, the physical communication chain—from source to coding, modulation, multiplexing, transceiver, medium, propagation, and antenna—will be complete. The final chapter then integrates these elements into complete system architectures.
The analysis now turns to the device that bridges circuitry and space: the antenna.
Back to reading