The basic structure and working principle of SAW device
From: Author: Publish time:2010-10-13 16:26 Clicks:496
SAW devices are made on the piezoelectric substrate, two acoustic - electric transducer - interdigital transducer, is formed on the surface of the piezoelectric
substrate shaped like two hands crossed metal pattern, and its the role is to achieve the sound - electricity conversion. The working principle of a surface acoustic wave device is that the transducer (input transducer) at the left end of the substrate converts the input electrical signal into an acoustic signal by means of inverse piezoelectric effect, which propagates along the surface of the substrate, The transducer (output transducer) converts acoustic signals into electrical signals.
The entire surface acoustic wave device functions by performing various processes on the acoustic signal propagating on the piezoelectric substrate and taking dvantage of the characteristics of the acousto-electric transducer.
SAW technology, there are some shortcomings. First of all, by the child by the process constraints, the working frequency of SAW devices is limited to 2-3GHz below,
in addition, because it uses single crystal material, the production process requires high precision, harsh conditions, making it more costly, the price is more expensive.
To date, many surface acoustic wave devices have been developed, such as surface-on-band pass filters, delay lines, matched filters, oscillators, and surface convolvers. SAW devices have been or are being used in radar, communications, air traffic control, electronic warfare, microwave relay, sonar, and television because of their small size, reliability, consistency, versatility and design flexibility Get a wide range of applications.
Surface acoustic wave (SAW) resonators,Its role is for automotive TPMS, remote keyless entry (RKE), safety systems and RFID tags.
With the progress of science and technology, in order to cope with the escalating car theft, people develop the anti-theft devices of various forms and structures with different generations. At present, the anti-theft devices can be classified into three categories according to their structure. The mechanical, electronic and network formula. Such as locks, locks and shift to the lock and other basic belong to the mechanical type anti-theft device, it is mainly reported to lock clutch, brake, throttle or steering wheel, gear to achieve the purpose of theft, at the same time with anti-theft and voice alarm. GPS satellites are able to silently deliver alarm information and alarm vehicle locations to alarm centers for car alarm systems (or other networked systems). A complete set of remote control car alarm should be
composed of the following sections:
(1) Host part: it is the core and control center of the immobilizer
(2) Sensing and detecting part: It can be composed of sensors or probes. At present, resonance sensors are commonly used, and microwave and infrared probes are rarely used.
(3) gated part: including the front cover switch, switch and luggage compartment switch
(4) alarm part: speaker
(5) Wiring section
(6) Other parts: including stickers, screws and relays and other accessories and instructions and installation wiring diagram
The same as the mobile phone works, remote control car alarm remote control (transmitter and anti-theft host system in addition to have the same launch and sale frequency, but also by the password to identify each other) Car alarm is good and bad, mainly by the three factors: anti-theft device product quality, anti-theft device installation methods and the proper use of anti-theft.
The main function principle of the SAW filter is to utilize the piezoelectric property of the piezoelectric material and convert the input signal of the radio wave into mechanical energy by using the input and output transducers (Transducer). After being processed, the mechanical energy is converted into the electric signal To filter unnecessary signals and noise, improve the quality of the recipient's message. SAW filters and SAW resonators are widely used in a variety of wireless communication systems,
televisions, video recorders and GPS receivers to replace the LC resonant circuit for interstage coupling and filtering. The main function is to filter noise, than the traditional LC filter installation easier and smaller. The disadvantage is that the insertion loss is greater than the LC resonant circuit.