How Antennas Receive

Explore Software Defined Radio — by Wolfram Donat (16 / 30)

👈 How Antennas Transmit | TOC | Antenna Design for SDR Hobbyists 👉

This brings us to talking about how to receive signals, and this is where we look at antenna shapes and sizes. As you probably figured out, shapes and sizes of antennas are determined by the frequency and polarization of the signal you’re trying to catch.

Let’s look at how to receive horizontal and vertical polarization first (the simplest). Just like the broadcasting antenna, these are best received by monopole or dipole antennas.

You may notice that the length of the antenna is explicitly depicted in both figures; this is because in both cases, the length of the antenna poles has a specific relationship to the wavelength of the received signal. A monopole antenna will experience the best reception if the antenna is one-quarter the length of the signal wavelength. A dipole, being really nothing more than two monopoles stuck together, will get the best reception if the total length of the antenna (both monopoles measured together) is one-half the signal’s wavelength.