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An antenna is a piece of equipment used to receive and transmit electromagnetic waves. It uses an oscillating current to create an electromagnetic field and then emit electromagnetic waves. When receiving a signal, the electromagnetic wave received by the antenna causes the current to oscillate in it, thus converting the signal into electrical energy to achieve wireless signal transmission and reception. It plays a key role in industry, communications, aerospace healthcare and consumer electronics.
When selecting an antenna, the first consideration is the frequency range to ensure that the selected antenna meets the frequency range of the application. So how does an antenna pick the right frequency? The process of selecting the appropriate frequency for an antenna involves several factors, and here are some key points:
1. Know the expected frequency of testing:first you need to know the expected test frequency and then choose an antenna that matches. Different antenna styles perform differently at different frequencies, and some perform better at certain frequencies.
2. Frequency Range and Wavelength:For low-frequency antennas (such as the kHz range), a single wave can be miles long, so even a quarter-wave antenna is about 10,000 feet long, which is impractical. Antenna elements at high frequencies (eg GHz) can be very small, but the signal propagates more like light, is very directional and does not go around or through objects. Therefore, low-pass signals are naturally more omnidirectional, while high-pass signals are more directional.
3. Dependence of bandwidth and frequency:Other antenna design factors, such as bandwidth, are also frequency dependent. High frequency requires more precise length elements, which makes it more difficult to build broadband high frequency antennas, but there are designs that can achieve this.
4. Active and passive:receive and transmit RF signals, although related, have different antenna requirements. The receiver requires a well tuned and sensitive antenna to receive a very small signal. To help weak signals, some antennas or receivers use active circuits to boost the incoming signal. These amplifiers are better placed near the antenna or on the antenna to reduce the chance of increasing noise, but ideally to boost weak signals. When used with a receiver, these amplifiers must be switched on when receiving and disabled when transmitting.
5. Beam width and antenna gain:Another factor in antenna selection is beam width or signal gain and directional. Directional antennas have a narrow beam width in the intended direction, while omnidirectional antennas have a more spherical distribution. Other antennas, such as the donut shape, have some steering. In this case, the signal does not spread much up or down, but really covers 360° in one plane.
6. Repeated repeated In an unobstructed environmentthere is no limit to the number of elements and independent rays that can be used on each individual, nor the degree to which the frequency can be repeatedly reversed. In addition, half of the beam can be polarized in one way, such as right circular or horizontal, and the other half can be orthogonally polarized, again doubling the number of possible users using the same frequency.
700-930MHz OMNI Fiberglass Antenna for Anti FPV Drones
https://www.uav-jammer.ru/700-930mhz-omin-fiberglass-antenna-for-anti-fpv-drone.html
Based on the test results, make adjustments if necessary. This may include changing the type of antenna, adjusting its position or orientation, or considering a different frequency.
