About Antenna Gain
Understanding how antennas focus RF energy to achieve apparent gain without creating power.
Description
Antenna Gain Explained delves into the fundamental principles behind antenna gain, a concept that often perplexes even seasoned RF engineers. The author, Marc, clarifies that antennas do not generate power but rather focus existing RF energy into desired directions, effectively reshaping the radiation pattern. He defines key terms such as decibel (dB), Antenna Gain, and Radiation Pattern, emphasizing the distinction between dBD (referenced to a ½-wavelength dipole) and dBi (referenced to an imaginary isotropic antenna), noting that dBi figures are 2.14dB higher.
The discussion illustrates how a standard ½-wavelength dipole's "doughnut" radiation pattern can be flattened into a "pancake" to achieve gains of 3dB, 6dB, or even 9dB by concentrating energy horizontally. Marc also explains how reflectors and directors are employed in directional antennas to further intensify radiation in a specific direction, potentially achieving gains as high as 20dB, albeit with a narrower effective angle. The concept of Front-Back Ratio is introduced for directional antennas, detailing how some energy inevitably radiates to the rear due to diffraction, even with solid reflectors.