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4G antenna design problems encountered how to deal with
Aug 22, 2017

4G antenna design problems encountered how to deal with?

In order to complete the global common, smart phones or tablet computers need to operate in a variety of bands and protocols. Of course, it is not required to work together in all bands and protocols, thus enabling the development of a 4G antenna system that can be tuned to the target operating frequency band. This conditional tunable antenna may be referred to as a "smart antenna" or "adaptive antenna". The fundamental principle is to limit the instantaneous operating frequency to one or two narrowband bands of interest to satisfy the protocol requests for a particular area. In this way, the request for broadband operations is reduced, allowing the antenna to be put into a more compact space, together without sacrificing radiation efficiency.

There are two fundamental ways of antenna tuning: feed point matching and aperture tuning. However, there are many elements that will affect the completion of these solutions to the resolution plan, and there is currently no single solution to suit each application.

Feed point matching point matching can be used for many antennas to complete, whether it is tunable or not tuned. The main function of the matching circuit is to complete the antenna terminal impedance and other parts of the radio system impedance (usually 50Ω) in wide-scale operating conditions. Typical tunable matching is done using a parallel or series variable capacitor as part of the impedance matching circuit. Adjusting the capacitance capacity can change the resonant frequency of the target circuit. WIFI antenna

Depending on the desired antenna scale to tighten and tune the scale, a large-scale capacity change is generally required to complete the frequency removal, thus generally requiring multiple tuning elements and / or wide-scale tuning values. Figure 1 shows the use of variable elements of the antenna point matching circuit.

Selective variable impedance matching circuit of the fixed broadband antenna aperture tuning aperture tuning is modified by the radiation components of the resonant structure completed. A typical way to do this is to use a simple switch to select a different load element on the antenna configuration. The switch load element affects the electrical length of the antenna, thereby changing the resonant frequency. Figure 2 is the use of fixed impedance matching circuit variable status, aperture tuning antenna AC circuit model.

Selection of fixed-point matching circuit variable status antenna

Whether the antenna is used for transmitting and receiving, it is necessary to be able to accept the maximum transmission power, and to maintain the outstanding features.

Case clarification

The following is an excellent illustration of the benefits of a fine tuning approach in terms of antenna volume reduction. Here is a 3D electromagnetic modeling program to analyze two different antenna devices: one is broadband programming; the other is able to tune in the same frequency scale, but the use of four tunable narrowband planning.