Antenna Technology and Microelectronics
- (Kerry Park, Seattle, U.S.A. - Jeffrey M. Wang)
- Radio Antenna
An antenna is an electrical device which converts electric power into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver. In transmission, a radio transmitter supplies an oscillating radio frequency electric current to the antenna's terminals, and the antenna radiates the energy from the current as electromagnetic (radio) waves. In reception, an antenna intercepts some of the power of an electromagnetic wave in order to produce a tiny voltage at its terminals that is applied to a receiver to be amplified.
In radio engineering, an antenna is the interface between radio waves propagating through space and electric currents moving in metal conductors, used with a transmitter or receiver. In transmission, a radio transmitter supplies an electric current to the antenna's terminals, and the antenna radiates the energy from the current as electromagnetic waves (radio waves). In reception, an antenna intercepts some of the power of a radio wave in order to produce an electric current at its terminals, that is applied to a radio receiver to be amplified. Antennas are essential components of all radio equipment.
An antenna is an array of conductors (elements), electrically connected to the receiver or transmitter. Antennas can be designed to transmit and receive radio waves in all horizontal directions equally (omnidirectional antennas), or preferentially in a particular direction (directional or high gain antennas). An antenna may include parasitic elements, parabolic reflectors or horns, which serve to direct the radio waves into a beam or other desired radiation pattern.
With regard to antennas, the basic rule of thumb is, the taller (or larger) the antenna is (in most cases), the more decibel (dB) gain it produces. The more dB gain, the better the performance.
- Two Major Antenna Categories
Antennas can be grouped into two major categories:
- Omni-Directional Antenna – These antennas radiate radio frequency (RF) energy in (more or less) a sphere. This 360-degree coverage from the antenna allows the RF power to be distributed equally in all directions. This type of antenna is used at locations that need to communicate to multiple other sites such as a master location or repeater location.
- Directional Antenna – As the name would imply, this type of antenna focuses the RF energy in one direction to both transmit and receive power. A directional antenna can be made in many different types such as parabolic dish, Yagi or corner reflector, but each will increase the signal in a single direction to maximize the energy to and from a single location. This type of antenna is best used at remote, fixed locations.
With a basic understanding of where best to use a specific type of antenna, there are additional terms involved in selecting an antenna for operation:
- Distributed Antenna System (DAS)
A distributed antenna system (DAS) is a network of antennas that sends and receives cellular signals on a carrier’s licensed frequencies. It improves voice & data connectivity for end user. A DAS is a network of spatially separated antenna nodes connected to a common source via a transport medium that provides wireless service within a geographic area or structure.
DAS antenna elevations are generally at or below the clutter level, and node installations are compact. A DAS is a network of antennas, connected to a common source, distributed throughout a building or an area to improve network performance. The spacing between antennas is such that each antenna gives full coverage without overlapping with other antennas, hence reducing the number of antennas needed to cover the whole building.
A DAS is a powerful signal enhancing system using direct feed from respective service carrier(s) to boost wireless signals. It is ideal when signals are too weak outside to use exterior antenna to catch and amplify those signals inside. A DAS may be deployed indoors (an iDAS) or outdoors (an oDAS) and can be used to provide wireless coverage in hotels, subways, airports, hospitals, businesses, roadway tunnels etc. The wireless services typically provided by a DAS include PCS, cellular, Wi-Fi, police, fire, and emergency services.
- Smart Antennas
Smart antennas (also known as adaptive array antennas, digital antenna arrays, multiple antennas and, recently, MIMO) are antenna arrays with smart signal processing algorithmsused to identify spatial signal signatures such as the direction of arrival (DOA) of the signal, and use them to calculate beamforming vectors which are used to track and locate the antenna beam on the mobile/target. Smart antennas should not be confused with reconfigurable antennas, which have similar capabilities but are single element antennas and not antenna arrays.
Smart antenna techniques are used notably in acoustic signal processing, track and scan radar, radio astronomy and radio telescopes, and mostly in cellular systems like W-CDMA, UMTS, and LTE. Smart antennas have many functions: DOA estimation, beamforming, interference nulling, and constant modulus preservation.
- Antennas and IoT
Antennas play a complex role in the dynamics of the IoT. As IoT ecosystems move to support high-density, low latency networks and continue to incorporate various new features into radios and overall system layouts, there is an even greater premium put on antenna system design. As a result, rather than view antennas as passive products – whether they are external or embedded – our engineers treat them as integral solutions in the creation of IoT applications and the creation of smart environments.
We are committed to identifying real world situations where the ability to effectively collect data and gather knowledge can lead to developing sustainable IoT solutions.
[More to come ...]
