The Basic lessons · Feedlines and antenna systems · B-006-009

Directing Signals: Parasitic Elements and Antenna Gain

Learn how adding unpowered elements focuses radio waves to increase signal strength in a specific direction. Understand how to calculate antenna gain and define the frequency range an antenna can use effectively.

This lesson is part of SignalPrep Pro. The subsection's 11 exam questions are free to practise: practise B-006-009.

What this subsection asks

• How is a parasitic antenna element energized?
• How can the directivity of a half-wave dipole be increased?
• If a half-wave dipole is converted to a Yagi by adding a slightly shorter parasitic element, in what direction(s) does the radiation strength increase?
• If a half-wave dipole is converted to a Yagi by adding a slightly longer element, in what direction(s) does the radiation strength increase?
• The property of an antenna that defines the range of frequencies to which it will respond, is called its:
• What is the approximate gain of a half-wave dipole in free space relative to an isotropic radiator?
• What is meant by antenna gain?
• What is meant by antenna bandwidth?
• In free space, what is the radiation pattern of a half-wave dipole?
• The gain of an antenna, especially on VHF and above, is quoted in dBi. The "i" in this expression stands for:
• An antenna is said to have a gain of 4.1 dBi. How much gain is this over a half-wave dipole antenna?