Distance Calculation Between MIMO Antennas

 

Distance Calculation Between MIMO Antennas

MIMO was mostly used in the 90’s, but it is still used in many modern RF technologies due to its reliability and spectral efficiency. MIMO is effective as it uses multiple antennas to transmit and receive signals however, with long-range equipment, there is interference, and upgrades are needed for improvement. The advantage of multiple antennas is that it allows not only to take multiple paths, but the direction of antennas can also be adjusted to change the path as desired. This greatly improves the reception rate and thus minimal bit error.

Distance Between Antennas:

The Distance Can Be Calculated By Far Field Distance Criteria As Below:

R = 2D²/𝜆

Here D is the diameter of the antenna and lambda is the wavelength of the signal, and R is the radius or the distance of coverage area/isolation distance. The above equation only represents a simplified version. The signals are transmitted in streams and are usually interpreted as a correlated matrix function. The MIMO representation for a vector-based reception model can be presented as below:

Y = Hx + n

here we represent the transmitter and receptor vector as y and x, respectively, and the H is used as the channel matrix. These systems always have some tendency of noise bring added, which in the above equation is represented by n. The H matrix is hard to solve, and sophisticated algorithms are developed to solve the matrix.

Figure 1 MIMO Representation Of Antennas

MIMO Has Three Diversity Modes Of Communication:

1-      Time Diversity

2-      Frequency Diversity

3-      Space Diversity

Time diversity allows to send off a signal at different time slots. The frequency diversity allows transmitting using different frequencies, whereas the space diversity makes use of antenna position to allow the radio paths.