The world is at a stage of rapid development and changes in the wireless communication technology sector. With this urgency and development, there is a great need for rapid communication portrayed with high speeds and capacity. This change influences the radio design and environment in equal measures on the electrical platforms. In the past, one radio was generally used singly and its connection was only made to a single antenna. With the current development, there is an adverse need for the integration and incorporation for multiple radio and also a whole bunch of antennas. Take for instance the example portrayed in the mobile devices used in the market today. A single device may have several cellular bands and therefore necessitating the need for RF filter. In such a case, the radios have to be designed in such a manner that they can actually use a number of antennas and in such creating a whole diversity for the application of MIMO antennae.
Recent Developments in the Field of MIMO Antenna Design
With the WLAN radio signals, three diversities have been used to ensure that the communication is reliable and also its quality is appropriate and meets the customer expectations. These are spatial diversity, orientation diversity and also a differentiated beam pattern. Spatial diversity is achieved by separating the two antennas as much as possible so as to achieve large areas between them. Spatial diversity is especially helpful in built-up areas and also in environments within indoors. In such, there is always a huge possibility that there will be no direct line of sight between the receiver and the transmitter. The signal from the transmitter will hence reach the receiver from multiple reflected paths causing attenuations.
To avert the multipath effect, antennae diversity is employed as the several antennae are likely to receive the single signal hence if one fails the with compensating for it. In this technique, it is fundamental that the antennas employed over the large spatial area have unique characteristics such that the reception and interpretation of the signals are the same. Also, the technique is important especially in the mobile industry for communication as several users can make use of a limited spectrum of communication and therefore avoiding co-channel interference.
When the orientation of the antennae is altered so as to attain an orthogonal orientation, polarization diversity is achieved. A combination of antennae pairs with polarization at orthogonal angles in such a manner that the slant between the horizontal and vertical line is approximately forty-five degrees. A complementary pair is then selected so that the system can be free from mismatches of polarization which in such an instance would cause the attenuation of signals. More so, the technique is crucial especially at the base stations for radio and mobile communication as it is not easily influenced by any antennae which may be near and transmitting signals in the same orientation.
In differentiated beam pattern combinations, a combination of several antennas which are collocated and each of them has a unique radio pattern which is different from the rest is used. In this case, directional antennas which in most instances have a physical separation that is very short are used. When the combinations are achieved, the antennae are able to make collective discrimination of numerous portions of angle space.
In signal processing, diversity switching has the main aim of ensuring that the multipath effects are greatly minimized. However, the MIMO technique takes advantage of the multipath signals in order to improve on the overall signal quality. For its optimal functionality, it is fundamental that the system utilizes several antennae but it only needs two of them to be operational. MIMO systems are usually very complicated and are always associated with greater cost and maintenances. Despite the disadvantage, they offer great services at the antennae level and also at the user level and hence many companies will approve their cost-related changes to their usefulness.
Considerations were taken in antenna design
Consider the common types of an antenna which are available
One should take note that there are several antennas in the market but several of them are commonly available and have been used in a wide range of applications. Some of the antenna designs available are the L-type, the F-type and also the monopole antennas. In most cases, the F-type antennae design is most common in the market and has a good comparison in terms of efficiency, directionality, and size.
Consideration of the circuit boards
Frequency has an inverse relationship with the PCB trace length and hence a higher frequency means a short trace length. In this regard, any antennae will need an area whose surrounding do not contain any trace of copper called the keep out area. In this case, only flashed gold or solder masks can be used and hence the performance of an antenna with greatly be affected by the type of material adopted and also its physical characteristics.
The environment where the antenna is to be used
Environmental factors can easily affect the effectiveness of an antenna. For instance, plastic and metallic components alter the turning and also the pattern of radiation of the antenna. This alteration, therefore, means that one should avoid locating the antenna in an area close to these substances and hence it can not be used around them.
Potential future services enabled by long-term antenna design developments
A change in the reconfiguration at the physical layer
In order to ensure the wireless communication are adapted well in the dynamics of the antenna technology, it is essential that there are techniques that are reconfigurable in such a manner the structure and also the parameters definition at the transverse can be altered depending on the circumstance. For example, the configuration change between the MIMO and spatial diversity taking into consideration that the two techniques have different functionalities. The future hence may hold such an algorithm to actuate the reconfiguration.
Again, the future of antenna design is headed towards the multi-user diversity. In this new technique, preference for communication is assigned to the channel where there is an undoubtedly chance of a completed transaction. When dealing with channels of the specular spatial type, this preference is assigned to the users that have the highest SNIR in the entire system. More so, in a case where there is rich scattering, the preference is assigned to those users with the greatest instantaneous capacity hence avoiding fading.