The Unwin Radar is a scientific

radar Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...

array at Awarua, near

Invercargill Invercargill ( , mi, Waihōpai is the southernmost and westernmost city in New Zealand, and one of the southernmost cities in the world. It is the commercial centre of the Southland region. The city lies in the heart of the wide expanse of t ...

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

. Unwin is part of the

Super Dual Auroral Radar Network The Super Dual Auroral Radar Network (SuperDARN) is an international scientific radar network consisting of 35 high frequency (HF) radars located in both the Northern and Southern Hemispheres. SuperDARN radars are primarily used to map high-la ...

(SuperDARN), an international radar network for studying the upper atmosphere and ionosphere that operates in the

High Frequency High frequency (HF) is the ITU designation for the range of radio frequency electromagnetic waves (radio waves) between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengths range from one to ten ...

(HF) bands between 8 and 22

MHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...

. The radar and associated research provides greater understanding of atmospheric weather, to assist with

weather prediction Weather is the state of the atmosphere, describing for example the degree to which it is hot or cold, wet or dry, calm or stormy, clear or cloudy. On Earth, most weather phenomena occur in the lowest layer of the planet's atmosphere, the t ...

, prediction of telecommunication interference and provide a better understanding of the effects of atmospheric magnetic fields on power grid management. The facility is operated by

La Trobe University La Trobe University is a public research university based in Melbourne, Victoria, Australia. Its main campus is located in the suburb of Bundoora. The university was established in 1964, becoming the third university in the state of Victoria an ...

and was named after Bob Unwin, a pioneer in auroral radar research,G.J. Frase
The antecedents and subsequent development of scientific radar in New Zealand
in

Journal of Atmospheric and Solar-Terrestrial Physics The ''Journal of Atmospheric and Solar-Terrestrial Physics'' is a monthly peer-reviewed scientific journal covering the atmospheric and solar-terrestrial physics. It was established in 1950 as the ''Journal of Atmospheric and Terrestrial Physics'', ...

, Volume 67, Issue 15, October 2005, Pages 1411-1418 who first proposed the concept behind the project in the 1960s
Unwin Radar
' on Venture Southland website, retrieved 2011-04-12

Operation

Bursts of

shortwave radio Shortwave radio is radio transmission using shortwave (SW) radio frequencies. There is no official definition of the band, but the range always includes all of the high frequency band (HF), which extends from 3 to 30 MHz (100 to 10 me ...

pulses are transmitted from the radar in a southern arc that includes the South Magnetic Pole. The ensuing reflections from

micrometeorite A micrometeorite is a micrometeoroid that has survived entry through the Earth's atmosphere. Usually found on Earth's surface, micrometeorites differ from meteorites in that they are smaller in size, more abundant, and different in composition. T ...

s, the

ionosphere The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an ...

ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wo ...

and

aurora An aurora (plural: auroras or aurorae), also commonly known as the polar lights, is a natural light display in Earth's sky, predominantly seen in high-latitude regions (around the Arctic and Antarctic). Auroras display dynamic patterns of bri ...

are detected at the station and resolved there. The TIGER-Unwin is a monostatic, pulsed radar that operates in the 8 MHz - 20 MHz range. The transmitting antenna consists of an array of 16

log periodic antenna Log most often refers to: * Trunk (botany), the stem and main wooden axis of a tree, called logs when cut ** Logging, cutting down trees for logs ** Firewood, logs used for fuel ** Lumber or timber, converted from wood logs * Logarithm, in mathem ...

s. * These antennas form a narrow beam ~4 degrees (at 12 MHz) that is swept across the radar footprint in 16 steps (one step per antenna array). * In the vertical direction the beam is ~30 degrees with a maximum in the range of 15 degrees (at 20 MHz) to 35 degrees (at 8 MHz). An additional four antennas placed some distance behind the transmitting array. These antennas are used to form an interferometer receiving array that measures the elevation angle of echoes. In the ''standard operation mode'' the radar uses

frequency hopping Frequency-hopping spread spectrum (FHSS) is a method of transmitting radio signals by rapidly changing the carrier frequency among many distinct frequencies occupying a large spectral band. The changes are controlled by a code known to both tra ...

where the transmission frequency changes to accommodate changing ionospheric conditions. This

is done by ongoing scanning the frequency band to determine automatically which channels are free of interference and provide the best coverage. The data from Unwin is transmitted back to

where it is made available over the Internet to users. The Unwin Radar and its counterpart at

Bruny Island Bruny Island ( Nuenonne: Lunawanna-alonnah) is a island located off the south-eastern coast of Tasmania, Australia. The island is separated from the Tasmanian mainland by the D'Entrecasteaux Channel, and its east coast lies within the Tasman S ...

Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...

form the Tasman International Geospace Environment Radar (TIGER). The Southland region is regarded as an ideal location for such a facility because of the southerly aspect, low radio noise and unobstructed horizon.

References

Buildings and structures in Southland, New Zealand Science and technology in New Zealand La Trobe University Radar {{physics-stub