Table of Contents
Why are loop antennas preferred for some specific applications?
A small loop antenna has low radiation resistance. If multi-turn ferrite core constructions are used, then high radiation resistance can be achieved. It has low radiation efficiency due to high losses. Its construction is simple with small size and weight.
What is the advantage of loop antenna?
Benefits or advantages of Loop Antenna ➨It is light in weight. ➨It is simple and compact in structure. ➨It is economical. ➨It is suitable for portable applications such as direction finding etc.
What is a folded loop antenna explain its operation properties and applications?
A folded dipole is an antenna, with two conductors connected on both sides, and folded to form a cylindrical closed shape, to which feed is given at the center. The length of the dipole is half of the wavelength. Hence, it is called as half wave folded dipole antenna.
What are the different types of loop antenna?
There are two types of loop antenna: electrically small loop antennas and electrically large loop antennas. If the total loop circumference is less than one-tenth of the wavelength, the loop antenna is considered electrically small. The circumference of an electrically large loop antenna is close to a wavelength.
How is loop antenna used as direction finder?
Since the directional response of small loop antennas includes a sharp null in the direction normal to the plane of the loop, they are used in radio direction finding at longer wavelengths. The procedure is to rotate the loop antenna to find the direction where the signal vanishes – the “null” direction.
Is loop antenna directional?
A significant advantage of a loop antenna is its directional pattern, a “figure 8” shape with two null points separated by 180 degrees. The null in reception that is located at right angles to the plane of the loop can be used for interference reduction.
What are the application of folded dipole?
The following are the applications of half-wave folded dipole antenna − ▪ Mainly used as a feeder element in Yagi antenna, Parabolic antenna, turnstile antenna, log periodic antenna, phased and reflector arrays, etc. Generally used in radio receivers. Most commonly used in TV receiver antennas.
Why are folded antennas used?
One of the main reasons for using a folded dipole antenna is the increase in feed impedance that it provides. If the conductors in the main dipole and the second or “fold” conductor are the same diameter, then it is found that there is a fourfold increase (i.e. two squared) in the feed impedance.
What is the gain of a loop antenna?
A loop antenna on top of a metal plate can provide a higher gain than that of a dipole antenna. The designed loop antenna is self-matched to the 50-ohm impedance of a source and provides a high directional gain of 8.2 dBi. The antenna gain is increased to 10.0 dBi by using a dual multi-loop geometry.
What is the impedance of a loop antenna?
The input impedance of a loop antenna at natural resonance is quite high, ranging anywhere from ~10 kΩ to 50 kΩ. This characteristic high input impedance is a result of the loop antenna operating in a parallel-resonant mode at the desired frequency of operation.
How do loop antennas work?
A loop antenna is a radio antenna consisting of a loop or coil of wire, tubing, or other electrical conductor, that is usually fed by a balanced source or feeding a balanced load. Resonant loop antennas have a two-lobe radiation pattern peaking at directions normal to the plane of the loop.