Helical antennas have various broadband characteristics, whether they are directional characteristics, impedance characteristics or polarization characteristics are broadband, and have the advantages of small size, light weight, wide frequency bandwidth, and good circular polarization characteristics, so they have been widely used application.
An Introduction of Drone Helical Antenna
Author: Site Editor
Publish Time: 2022-10-17
What is a drone helical antenna？
A helical antenna is an antenna with a helical shape. It consists of a metal helix with good electrical conductivity, usually fed by a coaxial wire. The core wire of the coaxial wire is connected to one end of the helix, and the outer conductor of the coaxial wire is connected to the grounded metal mesh (or plate). The radiation direction of the helical antenna is related to the circumference of the helix. When the circumference of the helix is much smaller than a wavelength, the direction of the strongest radiation is perpendicular to the helix axis. When the circumference of the helix is on the order of a wavelength, the strongest radiation appears in the direction of the helix axis.
The radiation ability of the helical antenna was discovered by the American scientist John D. Kraus in the experiment in 1947. Since then, the helical antenna has a nearly uniform resistive input impedance in a wide frequency band and the "super gain" in the same frequency band. "The lobe pattern working characteristics of endfire arrays have quickly been widely used in various fields.
At present, wireless personal area network (WPAN) technologies such as Bluetooth, HomeRF, HiperLAN and wireless local area network (WLAN) technologies such as IEEE802.1la and IEEE802.11b are developing rapidly. Among them, IEEE802.1la and HiperLAN use 5.2GHz ISM (Industrial, Sci2entific, Medical) frequency band, while Bluetooth, HomeRF and IEEE802.11b use the 2.45GHz ISM frequency band, they all put forward low cost, small size, easy matching and other requirements for the antenna, resulting in a variety of new antennas emerge in an endless stream.
Helical antennas have various broadband characteristics, whether they are directional characteristics, impedance characteristics or polarization characteristics are broadband, and have the advantages of small size, lightweight, wide frequency bandwidth, and good circular polarization characteristics, so they have been widely used applications.
Technical specifications of helical antenna
Pattern: The radiation pattern of the antenna (referred to as the pattern) is a graphical representation of the variation of the radiation parameters of the antenna with the spatial direction. The so-called radiation parameters include the power density, field strength, phase and polarization of the radiation. In the usual case, the radiation pattern is measured in the far-field region and expressed as a function of the spatial direction coordinates (called the direction function). In fact, what we are most concerned about is the spatial distribution of the radiated energy of the antenna. Unless otherwise specified, the radiation pattern generally refers to the spatial distribution of the power flux density, and sometimes refers to the spatial distribution of the field strength. From the analysis of the electric fundamental oscillator, although the electromagnetic wave radiated by the antenna is a spherical wave, it is not a uniform spherical wave. Therefore, the radiation field of any antenna is directional. The so-called directivity is the relationship between the relative value of the antenna radiated field and the spatial direction under the condition of the same distance.
Directivity coefficient: The directivity coefficient of the transmitting antenna characterizes the concentration ability of the energy radiated by the antenna in the spatial distribution. Defined as the ratio of the radiation intensity of the antenna in a given direction to the average radiation intensity under the same radiated power, that is, the directivity coefficient of the receiving antenna represents the ability of the antenna to receive electromagnetic energy from space. It is defined as the same incoming wave field strength. The ratio of the power output to the load when the antenna receives in a certain direction to the power output to the load lubricatingly in the same direction by the point source antenna.
Gain: Under the same input power, the ratio of the square of the electric field intensity generated by an antenna at a certain point (E2) to the square of the electric field intensity generated at the same point by a lossless ideal power supply antenna is called the antenna at this point.
Input impedance: The antenna is connected to the transmitter through the transmission line. The antenna acts as the load of the transmission line, and there is an impedance matching problem with the transmission line. The connection between the antenna and the transmission line is called the input end of the antenna, and the impedance value presented at the input end of the antenna is defined as the input impedance Zin of the antenna, which is the ratio of the input voltage Uin to the input current Iin at the antenna feed end.
Polarization: Polarization is a radiation characteristic that describes the spatial direction of the electromagnetic wave field vector. Generally, the spatial orientation of the electric field vector in the maximum radiation direction of the antenna is used as the polarization direction of the electromagnetic wave. The polarization of an antenna refers to the spatial orientation of the antenna's far-field radiated electric field in a given direction. In general, it is the spatial orientation of the electric field of the antenna in the direction of maximum radiation. In fact, the polarization of the antenna changes as it deviates from the maximum radiation direction, and the antenna can have different polarizations in different radiation directions. An antenna cannot receive a polarization component orthogonal to it. Antenna polarization can be divided into linear polarization, circular polarization and elliptical polarization. Linear polarization is divided into horizontal polarization, vertical polarization and ±45° polarization.
Bandwidth: All electrical parameters of the antenna are related to the operating frequency. The operating frequency of any antenna has a certain range. When the operating frequency deviates from the center operating frequency of 0f, the electrical parameters of the antenna will deteriorate, and the allowable degree of deterioration depends on the operating characteristics of the antenna system. When the operating frequency changes, the degree of change of the relevant electrical parameters of the antenna is within the allowable range, and the corresponding frequency range at this time is called the frequency bandwidth (Bandwidth).
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The UAV positioning antenna is equivalent to the "eye" of the UAV. High-precision positioning technology includes compatibility with GPS, BDS, GLONASS, GALILEO and satellite-based augmentation systems, antenna beamforming, and provides multi-system and multi-directional strong satellite signals, provide centimeter-level (to millimeter-level) positioning accuracy, and at the same time effectively handle the interference between systems in the working environment of the multi-communication frequency band of the UAV, so that the UAV is always stable during flight, and provides high safety during automatic cruise, which can effectively avoid the "exploding" of the drone and ensure the reliability and controllability of the drone in work.
The traditional UAV helical antenna is limited by the height of the antenna, so it is difficult to integrate the antenna with the UAV fuselage. In the iterative process of UAV antenna products, Mide antenna mainly starts from two directions: one is to further improve the performance of the product on the basis of the innovation of the antenna solution; the other is to make the product more suitable for the customer terminal machine type development.
In response to the application needs of the UAV industry, Mide provides professional UAV antennas, aviation antennas, UAV data link radios and other series of products for industry UAV customers, flexibly meet the differentiated needs of different UAV products, and make drone operations more intelligent and efficient.