What Is A MIMO Antenna?

MIMO Antennas represent multiple inputs and multiple outputs. Usually used for ieee 802.11n, but it can also be used for other 802.11 technologies. Mimo technology can be roughly divided into two categories: transmit/receive diversity and spatial multiplexing. Mimo antenna is sometimes called spatial diversity, because it uses multiple spatial channels to transmit and receive data, and the capacity of the channels can be improved by using mimo technology.

Classification of MIMO Antennas

MIMO antenna can be divided into SISO (single input single output), MISO (multiple input single output), SIMO (single input multiple output), MIMO and cooperative MIMO according to its system.

(1) SISO, which adopts single antenna transmission and single antenna reception. Theoretically, the information capacity of single antenna is limited by the SNR of the link. 

(2) MISO, which adopts multi-antenna transmission and single-antenna reception. The base station adopts multi-antenna transmission, and all end users served by the base station can obtain transmission diversity gain, and the link capacity increases logarithmically with the increase of the number of antennas.

(3) SIMO, using single antenna transmission and multi-antenna reception, all end users served by the base station can obtain the reception diversity gain, and the link capacity increases logarithmically with the increase of the number of antennas.

(4) MIMO, which adopts multi-antenna transmission and multi-antenna reception, and the combination of different antenna configurations between transmitter and receiver can greatly improve the data transmission rate and system capacity.

Application of MIMO Antenna

Mimo application in 3g The research on mimo technology has entered a relatively mature stage. But up to now, mimo has rarely been commercially implemented in cellular systems. In addition to the mimo scheme, 3G (Third Generation) has not adopted any MIMO scheme. There are two main factors affecting the large-scale commercialization of mimo systems: one is the antenna problem. In mimo system design, the number and spacing of antennas are very important system parameters. For the terminal, 1/ 2 wave length spacing is enough to ensure uncorrelated fading, and it is possible to use two antennas at most. For the mobile phone, installing two antennas may be a problem. This is because the trend of mobile phone design is to put the antenna in the cover to improve the attractiveness of the appearance, which makes the requirement of spacing almost harsh. The second is the complexity of the receiver. Firstly, the estimation of mimo channel in the receiver increases the complexity. In addition, the complexity also comes from the special rf (radio frequency), hardware and receiver advanced separation algorithm. The compatibility of the system with existing non-mimo networks, the fact that ITU (International Telecommunication Union) has not yet unified mimo channel model, and the consideration of csi (channel status information) of the transmitter also need to be considered. 2. Other applications of mimo technology mimo technology has been widely used in the field of fixed broadband wireless access, and the main companies adopting mimo are iospan wire2less and raze technologies. The airburst system of iospan wireless is an fdd (frequency division duplex) system based on mimo-ofdm orthogonal frequency division multiplexing. Raze technologies' skyfir system also has mimo interface and can be upgraded with beamforming controller.

Types of MIMO Antennas

What is a Magnet antenna?

Structure of Magnet antenna

1.The antenna radiator is made of stainless steel, pure copper, memory alloy and other materials, and its shape is generally whip or rod. The radiator of sucker antenna is actually a monopole (whip) antenna, which is an arm of a symmetric oscillator perpendicular to an ideal conductor plane (ground). According to the antenna principle, the resonant frequency of the wire antenna is an integer multiple of 1/2 wavelength. According to the mirror image principle, the ideal minimum electrical size of the magnet antenna is 1/4 wavelength on the ideal infinite plane. If the gain is to be improved, we can increase the length of the antenna radiator (an integer multiple of 1/4 wavelength) by adding inductance in the middle.

2.The function of the strong magnetic base is to fix the whole antenna and ensure that the magnet antenna is in conductive contact with the sucked metal. 

3. Cables generally include RG series (RG58, RG174) and 3D wires.

4. The common types of antenna connector are: N-head, SMA, BNC, TNC, I-PEX, etc. Among them, the common Connectors of magnet antennas are N-head, SMA, BNC, TNC, etc., which are divided into male and female. When selecting antennas, you must buy connectors that match the equipment.

Two points that should be paid attention to when using Magnet antenna

It is required to be adsorbed on the top of the cabinet or locomotive to ensure the height and radiation direction, so as to give full play to the antenna's best performance; If installed in other parts, it will cause standing waves, patterns and elevation changes, affecting the communication range. 2. Try to install the antenna in a wide field of vision and avoid installing it in a shaft or in a place with complex electromagnetic environment. Only in this way can the communication quality be improved and unpredictable interference phenomena such as background noise be reduced.

The purpose of Magnet antenna

Speaking of the use of magnet antenna, let's talk about its advantages first. If the installation method is correct, the standing wave ratio of magnet antenna is better and more efficient than that of built-in antenna, and there is no need for customization. Under the same frequency band and structural size as the glue stick antenna, the gain is higher and the transmission distance is longer, and different installation positions can be selected according to actual use requirements. In addition to the above advantages, the magnet antenna also has a wide range of uses, in addition to our daily vending machines, express cabinets, car radios, but also suitable for wireless modules and wireless gateways with medium gain requirements.

The Magnet antenna can be used in outdoor electric boxes and automobiles. When used outdoors, the radome can be made of FRP and other materials, which can be waterproof and windproof.

The magnet antenna can also be used in vending machines. The base of the antenna is a strong magnetic sucker, which is easy to install and difficult to fall off.