Since the launch of digital TV, various TV receiving products have been continuously launched in response to market demand. All products with dynamic displays will also be imported into the TV receiving function. The introduction of functions will cover notebook computers, PDAs, mobile phones and watches. Among the various portable products such as cameras and head-mounted displays, it has become the most widely used application after MP3; however, its ability to receive TV signals often determines the success or failure of product integration. The TV receiving antenna has become a key technology for this application. In view of this, some ideas for the development of the antennas will be provided for the development of the antennas, and consumers will have a basic understanding when purchasing various TV receiving products.
Classification of TV antennasDifferent receiving devices must be equipped with the most suitable receiving antennas. Various TV receiving antennas have their characteristics, advantages and disadvantages. The fixed outdoor antennas are common before digital TVs have been broadcast, and are fixed by VHF, UHF, V/UHF, etc. In the UHF band, consumers can purchase digital TV sets that are suitable for wireless reception (STB) and can display digital TV programs on the roof with UHF antennas.
The receiving antenna does not have the difference between digital and analog, only the difference of the frequency band; and the digital set-top box (STB) has the difference between receiving the cable (Cable) and the wireless signal, if the digital set-top box (STB) receiving the cable (Cable) receives the wireless Digital TV signals will be completely different in the way of transmitting signals, and their viewing ability will be inferior. The characteristics of the receiving antenna are directional high-gain antennas. Therefore, it is necessary to adjust the direction of the TV signal when installing and using. The launch pad is used to obtain the maximum gain. Generally, the strong wave device can be installed in the weak area of ​​the remote radio wave to enhance the signal amplitude for convenient viewing. Because it has directivity, it will not change after the general erection is fixed, and the volume is too large and not suitable for carrying or Action ratings.
However, the receiving performance of such a fixed outdoor antenna is difficult to be achieved by other types of antennas, and is therefore often used in areas where the radio waves are relatively weak. Strong-wave amplifiers are more suitable for directional antenna or cable signal reinforcement, in order to function; if used in omnidirectional (non-directional) antennas, although the signal is amplified, other unnecessary noise waves of the same frequency are also At the same time, zooming in, but reducing the ability to receive.
Fixed indoor antennas and fixed mobile receiving antennas, which are commonly installed in cars or attached to window glass and indoor antennas. This type of antenna has many types of products, including products with strong wave amplifiers. The fixed outdoor antenna is smaller and easier to install. The fixed extension cable not only provides the impedance matching between the antenna and the receiver, but also allows the consumer to place it in the best receiving position according to the place of use. Once installed in the best position in the room or in the car, it is not suitable for frequently changing positions to receive TV signals. It is also unsuitable for carrying capacity due to the weight and the power consumption of the amplifier, wiring installation, etc.
Although the receiving capability of this type of antenna is not as good as that of a fixed outdoor antenna, it is often used in environments where radio waves are not bad due to ease of installation and adjustment. It is also worth mentioning that in the mobile receiving capability, the radio wave transmission speed is much larger than the moving speed of the vehicle, and the radio wave cannot know the location of the receiving end, so its mobile receiving capability should be directly related to the environmental compatibility. For example, indoors, outdoors, inside the car, and the receiving environment outside the car are completely different, which will affect the receiving ability. Therefore, consumers must use this type of antenna to consider the use of the environment or the structure of the car body in order to achieve effective performance.
The portable mobile receiving antenna is a receiving antenna that can be easily carried or integrated with a portable product, that is, a television receiving antenna that allows a portable product to go there. To receive TV signals on portable products, the antenna must be miniaturized or built-in hidden antenna; due to the frequency wavelength, the half-wavelength 25 cm (600 MHz) antenna should be reduced to several centimeters for convenient carrying antennas. As well as designing narrow-band antennas (such as cell phone antennas) as broadband antennas that can be widely received, they are still technical bottlenecks all over the world, but "Diversity RecepTIon" has been adopted abroad.
Its principle is to configure two different antennas on the portable product to receive the TV signal at the same time, and then use the one with better signal quality. For example, Sanyo Electric uses the original telescopic antenna of the mobile phone (Whip Antenna), and then with the "earphone antenna" of the headphone cable, because there are two positions to receive the TV signal, even if one antenna is due to MulTIpath Interference, etc. Another antenna can also be used to receive the signal, so it is used to stably receive the TV signal, but this method is more power-consuming. Its TV tuner module needs 250mW; and its telescopic antenna is pulled out. Directivity and operability and other portable products that do not use headphone cords are extremely difficult to apply.
To design a practical portable mobile receiving antenna, I believe that there are several concepts to break through. The first one is that the portable product is also part of the receiving antenna body, so the design of the antenna and the portable product Structural design has an inseparable relationship. The second is that the receiving components and arrangements used in the portable products also have an innate decision relationship, so the acceptance of the effects must be considered in the selection and configuration of the components. Thirdly, since the portable product receives TV signals in terms of overall performance rather than the performance characteristics of a single component, the traditional evaluation method using a single component is completely unsuitable. Fourth, because it looks at the overall performance, its test method is also very different from the traditional antenna test method. Consumers need the overall performance, rather than the bright data.
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