03,20,2026 18views
Miniaturization of antennas
In recent years, the application of portable receivers has put forward an urgent demand for miniaturized GPS antennas. At present, GPS microstrip antennas and four arm spiral antennas mostly use high dielectric constant ceramic materials as dielectrics to achieve antenna miniaturization. By using ceramic substrates with s=28 instead of ordinary substrates with s=3, the size of microstrip antennas can be reduced by about 90%. Using a four arm spiral antenna with a ceramic dielectric of 40, the volume is only 1/6 of the original. However, the surface loss of such high dielectric antennas is relatively high and the efficiency is low. For four arm spiral antennas, miniaturization can also be achieved through techniques such as loading, bending, and partial folding. In the future, media with lower losses and higher dielectric constants, as well as special antenna structures, can be used to further reduce antenna size.
Reduce antenna costs
At present, microstrip antennas are relatively affordable and have an advantageous position in GPS applications. Although the dielectric loaded four arm spiral antenna has excellent performance, its structure is complex and the manufacturing cost is high, so it is only used in products. It can be seen that reducing the production cost of four arm spiral antennas is a necessary requirement to ensure the widespread application of GPS products.
Enhance anti-interference capability
GPS signals are highly susceptible to external interference, and for antennas, anti-interference is mainly achieved through beamforming technology and adaptive zeroing antennas [1]. Beamforming technology uses digital beamforming to direct the antenna beam to the satellite to be tracked, thereby adding gain to the desired signal. This method requires the use of a large aperture antenna array, which is computationally demanding. Adaptive zeroing antennas use electronic tuning to establish a zero point in the antenna pattern in the direction of the interference source, which can improve anti-interference ability by 40-50 dB. Adaptive fading antennas have been widely used in the US military. ”The GPS receivers on the Tomahawk missile, JDAM (Joint Direct Attack Munition), and F216 fighter jet all use adaptive zeroing antenna arrays. In addition, how to deal with severe multipath interference in cities is also a key issue in current applications.
Dual/Multi band Antenna
At present, the GPS system of the United States, the cL0NASS system of Russia, and the Galileo system of Europe can all provide navigation services. If a receiver can simultaneously receive two or even three satellite signals, it not only helps to observe more constellations and improve positioning accuracy, but also avoids the constraints of a single system. In addition, in addition to precision dual frequency measurement receivers, the integration of GPS technology and personal mobile communication terminals also requires an antenna that can solve the application problems of GPS and GSM, CDMA or 3G frequency bands. At present, microstrip antennas mostly use the method of patch stacking to achieve dual/multi frequency bands. For four arm spiral antennas, stacking up and down and nested inside and outside are commonly used. Another method is to replace each arm with three arms of different lengths to achieve the three band characteristic u. It is worth noting that the four arm spiral antenna has potential advantages in dual band antenna design, and its different working modes can be utilized to achieve dual/multi frequency characteristics.
