Software defined antenna
Encyclopedia
SDA - Software Defined Antenna, following and exploiting the concept of Software Defined Radio
Software-defined radio
A software-defined radio system, or SDR, is a radio communication system where components that have been typically implemented in hardware are instead implemented by means of software on a personal computer or embedded computing devices...

 (SDR), is an idea for an antenna system that can be adjusted in such way that similar characteristics can be maintained for any frequency. Once installed, SDA could be used to support any radio-based telecommunication
Telecommunication
Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...

 system in any band, with the same level of performance, e.g., GSM , then UMTS
Universal Mobile Telecommunications System
Universal Mobile Telecommunications System is a third generation mobile cellular technology for networks based on the GSM standard. Developed by the 3GPP , UMTS is a component of the International Telecommunications Union IMT-2000 standard set and compares with the CDMA2000 standard set for...

 after migration to followed by LTE
LTE Advanced
LTE Advanced is a preliminary mobile communication standard, formally submitted as a candidate 4G system to ITU-T in late 2009, was approved into ITU, International Telecommunications Union, IMT-Advanced and expected to be finalized by 3GPP in early 2011...

 in band.

The first mathematical research on SDA began in the late 1950s and focused on steering the side lobes
Side lobe
In antenna engineering, side lobes or sidelobes are the lobes of the far field radiation pattern that are not the main lobe....

 of radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

 receivers to be less susceptible to jamming
Radar jamming and deception
Radar jamming and deception is the intentional emission of radio frequency signals to interfere with the operation of a radar by saturating its receiver with noise or false information...

, but rapid developments in SDR technology are causing manufacturers to pay more attention to this subject in general.

A prototype software defined antenna was developed by Syntonics, a small U.S. company located in Columbia, Maryland working with researchers at the ElectroScience Laboratory of Ohio State University
Ohio State University
The Ohio State University, commonly referred to as Ohio State, is a public research university located in Columbus, Ohio. It was originally founded in 1870 as a land-grant university and is currently the third largest university campus in the United States...

. This prototype SDA uses small movable pixel elements to selectively form reconfigurable microwave transmission lines
Transmission line
In communications and electronic engineering, a transmission line is a specialized cable designed to carry alternating current of radio frequency, that is, currents with a frequency high enough that its wave nature must be taken into account...

 and radiating patch
Patch antenna
A patch antenna is a type of radio antenna with a low profile, which can be mounted on a flat surface. It consists of a flat rectangular sheet or "patch" of metal, mounted over a larger sheet of metal called a ground plane. The assembly is usually contained inside a plastic radome, which...

 elements. Under software control, changes to the size, shape, orientation and number of the radiating elements alter the frequency, polarization, gain and beam angle of the SDA based on external data input. Starting in 2004, the U.S. Department of Defense funded a series of feasibility and prototyping contracts to develop this SDA concept.

Measurements of this early prototype hardware, built with super sized pixel
Pixel
In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....

s wide, have demonstrated tunable patch antenna structures operating at microwave frequencies. A pair of these patch elements were formed along with microstrip
Microstrip
Microstrip is a type of electrical transmission line which can be fabricated using printed circuit board technology, and is used to convey microwave-frequency signals. It consists of a conducting strip separated from a ground plane by a dielectric layer known as the substrate. Microwave components...

 transmission lines to interconnect and feed the patches. Software defined variations in the feed lines created relative phase differences between the patches, thus steering the beam.

Large, conformal surfaces of this type could be easily reconfigured in near real time to provide beam steering of high gain antenna patterns. The ability to rapidly change frequency could also be advantageous for software defined radios that hop across large parts of the radio spectrum. SDAs could be used as multifunctional apertures connecting to different radios as the need arises.

It appears that one of the Scandinavia
Scandinavia
Scandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...

n-based telecommunication companies is also working on an operational prototype .
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