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AN4190 датащи(PDF) 25 Page - STMicroelectronics |
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AN4190 датащи(HTML) 25 Page - STMicroelectronics |
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25 / 29 page ![]() AN4190 Antenna advantages and disadvantages Doc ID 023812 Rev 1 25/29 3 Antenna advantages and disadvantages After the antenna theory, where the most important parameters of the antennas have been covered, and after the description of the main types of antennas that can be used in the sub- GHz bandwidth, a description of the main advantages and disadvantages of each antenna is shown here. ● Dipole antenna: this antenna is a very simple chip and presents a good gain. The main disadvantage is the large size at low frequency. ● Whip antenna: this antenna presents good performance with a size lower than a dipole antenna. A good ground plane is necessary to achieve good performance. ● Loop antenna: loop antennas are cheap and not easily detuned by nearby hand movements. They have the disadvantage of having poor gain, to be very narrowband and are difficult to tune. ● Spiral antenna: spiral antennas have a size lower than a whip antenna and are wideband. On the negative side, these types of antennas are difficult to feed. ● Helical antenna: helical antennas are very directive and have good gain. However, they have a bulky size and are easily detuned by nearby objects. ● Microstrip antenna: microstrip antennas have the advantage of being very cheap and have a simple and thin structure. As a negative, they are very large at low frequency. ● Ceramic antenna: ceramic antennas have the advantage of being separate components, have a small size and are less affected by environmental factors. The main disadvantages are the high cost, the medium performance and the matching function of the PCB size and shape of the ground plane. ● Slot antenna: slot antennas have the advantage of size, design simplicity, robustness and convenient adaption to mass production. The main disadvantage is the big dimension for low frequency that makes the slot antenna difficult to manage for frequencies lower than 433 MHz. The antenna advantages and disadvantages are summarized in Table 2. Table 2. Antenna types advantages and disadvantages Antenna types Advantage Disadvantage Dipole antenna – Very cheap – Good gain – Difficult to design for frequencies lower than 433 MHz – Large size at low frequency Whip antenna – Good performance – High cost Loop antenna – Cheap – Not easily detuned by hand movements – Poor gain – Very narrowband – Difficult to tune Spiral antenna – Lower size than whip – Wideband – Difficult to feed Helical antenna – Very directive – Good gain – Mechanical construction –Bulky size – Easily detuned by nearby objects |
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