Technical Notes

Diversity

What is the "Diversity"?

The "Diversity Antenna" is a group of several antennas to receive radio wave. The "Diversity System" is a system using radio wave efficiently by optimizing the signals from the Diversity-Antenna. In the town with many buildings or on fast moving vehicles, the environment of radio condition is changing by effect of phasing. In such situations, the diversity system can make radio conditions better. So it is useful for many applications such as TV in car, wireless LAN and cellular phone's antenna system.

Types of Diversity

Followings are types of diversity system.

Space Diversity: Receive by several antennas which are placed to keep a physical distance
Angle Diversity: Receive multipls signals by switching single antenna
Polarization Diversity: Conbine the multiple signals that are received via antennas with different polarization
Frequency Diversity: Receive by several frequencies
Time Diversity: Combine the multiple signals that are received at different time

Phasing

The signal is transferred over several different propagation paths. These each wave is received at differnet time and does interference each other. That is why the signal alternates strong and weak periodecally. This is called the "Phasing" that is achieved by using diversity system.

Application

Ther diversity system is used for the following applications widely.

TV broadcasting and telecommunication
TV receiver and tuners
Cellular phone
Wireless LAN
In-vehicle and mobile applications

Nowadays, space diversity and polarization diversity are mainly used for many diversity systems. Otherwise, frequency diversity and time diversity are coming for the terrestrial digital TV broadcasting.

What does Magna do for Diversity

Magna is researching and developing the diversity schemes especially for the terrestrial digital broadcasting. And Magna offers the diversity products for terrestrial digital broadcasting as follows.

Editor: Sho TAMAKI
Supervisor: Dynamite Matsuo