What is Archimedean spiral antenna?
The Archimedean spiral antenna is a popular of frequency independent antenna. Previous wideband array designs with variable element sizes (WAVES) have used the Archimedean spiral antenna as the radiating element.
What is the frequency range of spiral antenna?
Spiral antenna arrays are used in military aircraft in the 1-18 GHz range. Other applications of spiral antennas include GPS, where it is advantageous to have RHCP (right hand circularly polarized) antennas.
How does a spiral antenna work?
Spiral antennas transmit circularly polarized radio waves, and will receive linearly polarized waves in any orientation, but will drastically attenuate circularly polarized signals received with the opposite-rotation.
What is spiral cavity?
The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.75 turns around its axis, the modiolus.
How is antenna radiation efficiency calculated?
The radiation efficiency of an antenna is defined as the ratio of the outward radiated power by the antenna to the input power fed to the excitation port of the antenna. The power loss due to the port impedance mismatch is not considered here. For ideal lossless antenna, the radiation efficiency ( η r ) is 1.
How is antenna length determined?
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.
Why is cochlea coiled?
The spiral shape of the cochlea enhances its ability to detect low frequency sounds. Spiral with a purpose. Calculations show that the inner ear organ is shaped like a snail shell (above) in order to boost sensitivity to low frequencies.
How many coils are present in cochlear duct of man?
In the mouse, the cochlea stops elongating after 1.75 coils, while other mammals make 1.5–4 coils. The human cochlea coils 2.5 times.
What is antenna gain explain with its formula?
Antenna gain is the ability of the antenna to radiate more or less in any direction compared to a theoretical antenna. If an antenna could be made as a perfect sphere, it would radiate equally in all directions. Such an antenna is theoretically called an isotropic antenna and does not in fact exist.
What are the parameters of the Archimedean spiral?
The parameter a is simply a constant that controls the rate at which the spiral flares out. The second arm of the Archimedean spiral the same as the first, but rotated 180 degrees. A plot of the Archimedean spiral given in Equation  is shown in Figure 2: Figure 2. Archimedean Spiral Antenna, with a = 0.1.
What are the design parameters of a spiral antenna?
Number of Turns (N) – The number of turns of the spiral is also a design parameter. Experimentally it is found that spirals with at least one-half turn up to 3 turns work well, with 1.5 turns being a good number. Radiation occurs from the spiral antenna when the currents on the spiral’s arms are in phase.
What is the active region of an Archimedean antenna?
4 ,4−= (2.8) The Archimedean spiral antenna radiates from a region where the circumference of the spiral equals one wavelength. This is called the active region of the spiral.
What is an Archimedean spiral compressor?
Scroll compressors, used for compressing gases, have rotors that can be made from two interleaved Archimedean spirals, involutes of a circle of the same size that almost resemble Archimedean spirals, or hybrid curves. Archimedean spirals can be found in spiral antenna, which can be operated over a wide range of frequencies.