Will a 2 meter antenna work for 70cm?
So, an antenna that looks like a half wavelength on 2m will look like 1.5 wavelengths on 70cm. Although the radiation pattern is different, the antenna impedance is the same, and so will provide a good match to the radio in either case.
Does a 5’8 wave antenna need a ground plane?
The absence of a ground plane or very small ground plane will cause the matching circuit for the 5/8 wave to be a little different due to less capacitance between the vertical element and the ground plane, otherwise there is no “reflection or radiation from a second source” to produce gain in a 5/8 wavelength antenna.
What is an advantage of using a properly mounted 5/8 wavelength antenna?
While a 5/8 wave antenna will, indeed, exhibit an increase in signal strength at the lower angles, that increase is in the order of 3dB, (2-times the power) nowhere near the 10dB of a 10-times increase. Why are VHF or UHF mobile antennas often mounted in the center of the vehicle roof?
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What is the difference between 1/2 wave and 5/8 wave antenna?
The half wave dipole has 3 dB of gain over the quarter wave because it has twice the aperture, or capture area. And a 5/8 wave antenna is said to have about +3 dBi or +0.85 dBd of gain.
What makes an antenna dual band?
A dual-band antenna is an antenna that can send and receive radio frequency signals at two distinct frequencies. Depending on their configuration, these antennas are capable of using either of the two frequencies individually or at the same time.
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What is the gain of a 5’8 wave antenna?
4 dBd When used as a vertical radiator against a ground plane this translates to a length of 5/8 wavelength. It is found that a five eighths wavelength vertical antenna has a gain of close to 4 dBd, i.e. 4 dB gain over a dipole.
What is a 5’8 antenna?
Five eighths wavelength antenna concept The maximum level of radiation at right angles to the antenna is achieved when the dipole is about 1.2 times the wavelength. As a vertical monopole antenna is half the length of a dipole, this equates to about a five eighths wavelength vertical monopole antenna.
What is the difference between 1/4 wave and 1/2 wave antenna?
The size of a 1/4-wave antenna is approximately one-quarter of the wavelength of the desired frequency, and the 1/2-wave is one-half the wavelength. Therefore, a 1/2-wave receiver antenna would be about 3 feet (1 m) long, and a 1/4-wave antenna would be about 18 inches (45 cm).
Is a half-wave antenna better than a quarter wave?
A half-wave antenna is a good choice when your entire device is much smaller than a quarter-wavelength, or when you are building an antenna that is physically separated from the transmitter.
What wave length is best for a 5/8 antenna?
So, 5/8λ is about optimal for this style of antenna. A 5/8 wave provides a style of vertical radiation pattern which doesn’t offer energy in some of the mid- upper angles but compresses that 1/4 wave donut like stepping on it, to being flatter but WIDER.
How do you connect a 5/8 wave antenna to coax?
The 5/8 wave antenna consists of a vertical radiator which is fed at the base of the antenna. A matching device of some sort must be added between the antenna and the feedline if you wish to feed it with coax. Adding a coil in series with the antenna at the base is one such method of matching.
What should be the length of the vertical antenna element?
The radials are supposed to be 1/4λ, while the vertical active element should be 5/8λ, with a velocity factor of 0.98. However, when measuring the vertical antenna element: should the 5/8λ length be measured from the top of the coil up to the top of the element, or including the coil?
How to calculate the length of a QTH antenna?
It uses the standard formula, 585/f (178.308/f for metric) MHz to calculate the element lengths. If you’ve experimented with 5/8 wave antennas before and know of a better formula for your QTH, feel free to change the formula to suit. This formula is for a wire antenna.
