The current spreads to the edge of the triangular surface by taking paths with different lengths, so that resonance occurs not only at one frequency, but also at two or more. The overall result is a slightly flatter frequency response across the chosen range. A good strategy to improve the efficiency of this antenna is to use elements with a slightly different length. The use of two identical dipoles has the effect of increasing the cross-sectional area of the conductor so that the antenna has a better length/diameter ratio. Even the dipole can be transformed into a broadband antenna, using two identical dipoles powered by the same transmission line and arranged to form a “bowtie”. The thicknesses of the material can also have a decisive impact on the performance of the microstrip antenna. The choice of materials is critical and should be carefully studied during the design phase. The antenna power supply is in the center.įigure 2: schematic structure of a wire hollow Bowtie antenna The reception and transmission features of this type of antenna depend exclusively on the angle between the two pieces of metal, as can be seen in the figure 1. In this way the angles do not depend on the distance nor on the wavelength. It is possible to design antennas which work not only thanks to their length but to the extent of their angles.
These calculated lengths are only suitable for the desired reception frequencies but would be less effective at slightly different frequencies. For example, if we want to receive the 27 MHz frequency with a half-wave dipole, its length should be 5.5 meters while to receive the 500 MHz frequency with a half-wave dipole, its length should be 30 centimeters. Its size is related to the wavelength of the signal. In general terms, the operation and characteristics of an antenna depend on its length. The input impedance depends on the frequency and angle and the real part is between 70 and 500 ohms. Its lowest frequency depends on the flare length and angle. The gain is slightly higher than the dipole. These are butterfly-shaped antennas formed by a folded conductive wire and, recently, also in a microstrip. A butterfly antenna is a common type of broadband antenna similar to a two-dimensional conical dipole. The concept of tie or butterfly antenna is not very complicated. The impact of digital telecommunication has resulted in a significant improvement in picture quality on TV. Let’s start the analysis from the normal butterfly antenna (bowtie antenna). Reducing the size of an antenna also affects the Q factor. Unfortunately, the perfect coupling is impossible when the antenna becomes extremely small, as difficulties increase for this purpose. This problem is almost eliminated if it fits perfectly with the load. If the size of an antenna is reduced, the gain, efficiency, and bandwidth will also tend to reduce. There is often a great difficulty for a perfect adaptation to the 50-ohm load the radiation diagram, as its size decreases, tends to approach that of the classic omnidirectional vertical dipole in the horizontal plane, with a figure of eight in the vertical plane they require specific design techniques, sometimes even very complicated ones. The input impedance is highly capacitive or inductive, while its resistive component is very low. Small antennas have some specific characteristics that differ from antennas of comparable size in their wavelength: Antennas of different shapes have been studied to obtain miniaturization and bandwidth and the butterfly or tie one is one of the most effective. Wide bandwidth microstrip antennas get a lot of interest from designers due to their flexibility and simple adjustment options. Today, miniaturized devices require the use of antennas that are smaller than their wavelength.