RFMonopole vs. Dipole Antennas: Key Differences Explained
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This article explores the differences between monopole and dipole antennas, two popular choices for cellular phones, broadcasting, and wireless communications, largely due to their omnidirectional characteristics.
Monopole Antenna
Figure 1: Monopole antenna with its radiation pattern. The figure also shows a folded monopole antenna.
The monopole antenna essentially leverages an “image” created through a metal or ground plane. You’ll find variations of the monopole antenna like the inverted-L and inverted-F types. These are particularly common in handheld portable telephones.
Dipole Antenna
Figure 2: Dipole antenna with its radiation pattern. The figure also shows a folded dipole antenna.
The most common type is the half-wave dipole, which consists of a wire or rod that’s half a wavelength long. The antenna is divided into two quarter-wavelength sections, and the transmission line connects at the center point.
A dipole antenna usually has an impedance of around 73 Ohms. Typically, these half-wave dipole antennas are mounted horizontally, resulting in horizontal polarization. The radiation pattern resembles a doughnut shape. As the wavelength multiples change (lambda), so does the radiation pattern, as illustrated in Figure 2.
Key Differences Summarized
To put it simply, the monopole antenna uses a ground plane to create a virtual “half” of an antenna, whereas the dipole antenna is a complete antenna consisting of two radiating elements.
