How is electrical antenna length calculated?
To calculate the electrical length of the line you need to multiply the velocity factor of the line (available from the supplier of the line) by the free space length. For the length in feet, this is (983.6 / frequency in MHz) * velocity. For the length in meters, this is (299.8 / frequency in MHz) * velocity.
What does a longer antenna do?
The most important aspect of a radio antenna is that it is properly matched to your radio and the frequency band you’re operating on. Theoretically, a longer antenna will have a greater range, but it is far more important for optimal radio performance that the length of the antenna matches the frequency.
What is the electrical length of a transmission line?
The electrical length can also be expressed in terms of wavelength noting that 360◦ corresponds to 2π radians which corresponds to λ. Thus ℓe = (3 radians) = 3 × 180/π = 171.9◦ or as ℓe = 3/(2π) λ = 0.477 λ. A transmission line ends (i.e., is terminated) in an open circuit.
What is electrical length of antenna?
The electrical length of an antenna element is, in general, different from its physical length For example, increasing the diameter of the conductor, or the presence of nearby metal objects, will decrease the velocity of the waves in the element, increasing the electrical length.
What is the relation between antenna length and wavelength?
The length of the antenna is inversely proportional to the frequency and directly proportional to the wavelength. The higher the frequency and the shorter the wavelength, the shorter the antenna can be made.
What is electrically long?
By contrast, an electrically long line is one where the propagation time is a large fraction or even a multiple of the signal period. A “long” line is generally considered to be one where the source’s signal waveform completes at least a quarter-cycle (90° of “rotation”) before the incident signal reaches line’s end.
How does frequency affect antenna length?
How do you increase the length of a dipole antenna?
In a dipole antenna both driven conductors must be that long, for a total dipole length of (2N+1)λ /2. For example, increasing the diameter of the conductor, or the presence of nearby metal objects, will decrease the velocity of the waves in the element, increasing the electrical length.
What affects the electrical length of an antenna?
The electrical length of an antenna element is, in general, different from its physical length [better source needed] For example, increasing the diameter of the conductor, or the presence of nearby metal objects, will decrease the velocity of the waves in the element, increasing the electrical length.
What is electrically short and electrically long antenna?
An antenna which is shorter than its resonant length is described as ” electrically short “, and exhibits capacitive reactance. Similarly, an antenna which is longer than its resonant length is described as ” electrically long ” and exhibits inductive reactance.
What is the purpose of a coil in an antenna?
Loading coil in a cellphone antenna mounted on the roof of a car. The coil allows the antenna to be shorter than a quarter wavelength and still be resonant. An antenna’s effective electrical length can be changed without changing its physical length by adding reactance, ( inductance or capacitance) in series with it.