Table of Contents
What affects the gain of an antenna?
As a practical matter, the maximum directive gain (directivity) of an antenna depends upon its physical size compared to wavelength. The uniformly illuminated aperture type of antenna has been found to give a higher gain in practice than other antennas, at least for large apertures.
How do you adjust a dipole antenna?
To raise the frequency of minimum SWR, trim the antenna shorter. Cut each of the dipole’s segments by equal amounts so that the two halves maintain equivalent lengths. If the minimum SWR is minimized at a higher frequency than desired, you must lengthen the wire segments.
What is the gain of a dipole antenna?
When mounted horizontally, the radiation peaks at right angles (90°) to the conductor, with nulls in the direction of the dipole. Neglecting electrical inefficiency, the antenna gain is equal to the directive gain, which is 1.5 (1.76 dBi) for a short dipole, increasing to 1.64 (2.15 dBi) for a half-wave dipole.
What is the difference between high gain and low gain antenna?
Gain of an antenna system is the increase or ‘amplification’ in signal power, usually expressed in decibels. So, a high-gain antenna is particularly good at transmitting signals in a narrow beam whereas a low-gain antenna tends to send its signal in a much wider sweep of directions.
How do you calculate antenna gain?
The gain of an antenna A compared to an antenna B is equal to the capture area of antenna A compared to the capture area of antenna B. The capture area of an antenna is determined by multiplying the antenna’s radiator length by 1/4 lambda.
What is the best wire for an antenna?
The best mobile cb antenna is considered a top-loaded antenna, and is usually made of fiberglass. The coil is tin wire wrapped around the antenna and then covered with a protective shield. The top-loaded is the cheapest and most effective antenna.
What is antenna peak gain?
A gain standard antenna is a test antenna with an accurately known gain and polarization (typically linear). The most popular types of gain standard antennas are the thin half-wave dipole antenna (peak gain of 2.15 dB) and the pyramidal horn antenna (where the peak gain can be accurately calculated and is typically in the range of 15-25 dB).
How do you calculate the length of a dipole?
Enter the desired operating frequency in megahertz to get a good starting length for a dipole in both feet and meters. The formula for calculating the approximate length of a dipole is: Dipole length in feet: 468 / frequency in MHz. Dipole length in meters: 143 / frequency in MHz. These are only approximate values.