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Quarter Wave Ground Plane Antenna Formula:
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A quarter wave ground plane antenna is a type of radio antenna consisting of a vertical radiator that is a quarter wavelength long, mounted perpendicular to a conductive surface (ground plane). It's widely used for VHF and UHF communications due to its simple construction and omnidirectional radiation pattern.
The calculator uses the quarter-wave antenna formula:
Where:
Explanation: The formula calculates the optimal length for a quarter-wave antenna based on the operating frequency, using the fundamental relationship between wavelength and frequency.
Details: Accurate antenna length calculation is crucial for optimal signal transmission and reception. A properly sized antenna ensures maximum efficiency, proper impedance matching, and optimal radiation pattern for the desired frequency.
Tips: Enter the desired operating frequency in Hertz (Hz). The calculator will determine the optimal quarter-wave length for your antenna. Frequency must be a positive value greater than zero.
Q1: Why quarter-wave instead of full-wave?
A: Quarter-wave antennas are more compact and easier to construct while still providing good performance. They offer a good compromise between size and efficiency.
Q2: What materials are best for constructing these antennas?
A: Copper or aluminum rods/tubes are commonly used for the radiator element due to their excellent conductivity and durability.
Q3: How does the ground plane affect antenna performance?
A: The ground plane acts as a reflector, creating the image of the missing quarter wavelength and making the antenna behave like a half-wave dipole with a low radiation angle.
Q4: Can this calculator be used for different frequency units?
A: The calculator requires frequency in Hertz. Convert MHz to Hz by multiplying by 1,000,000 (e.g., 146 MHz = 146,000,000 Hz).
Q5: What is the typical impedance of a quarter-wave ground plane antenna?
A: A quarter-wave monopole over a perfect ground has an impedance of approximately 36 ohms. With typical ground planes, the impedance is around 50 ohms, making it well-suited for standard coaxial cable.