Jicamarca Radio Observatory

Jicamarca can only fit in a picture when photographed from one of mountains around the observatory. The view  is dominated by the 300x300 49.92 MHz 3 MW incoherent scatter radar that is the largest in the world in terms of size. One can also see the SOUSY radar on the bottom center. 

Peru is one of the most unlikely world super powers of radar. This is largely due to the fact that the Jicamarca Radio Observatory was established there in the early 60s at the outskirts of Lima. Even though the radar has some rust on it, it is still one of the most capable and flexible incoherent scatter radars in the world. Jicamarca is kind of like LOFAR and KAIRA-- a radio science playground. The radar and various transmitters and antennas at the observatory can be mixed and matched on very many different ways to implement many completely different remote sensing experiments. Many new radar methods used now all around the world have also been developed at the observatory.

One special feature of the radar is that is resides at the geomagnetic equator. Due to the narrow incoherent scatter spectrum when viewed with a 90 degree aspect angle to the magnetic field, the radar can be used to measure very precise East-West drift velocities.  Other special features of the radar are interferometric imaging of perpendicular to the magnetic field ionospheric irregularities, interferometric angle of arrival determination of meteors, and absolute calibration of electron density using Faraday rotation from two different characteristic propagation modes of radio waves in the ionosphere. 

It is impossible to go through all the capabilities, science, and history behind this wonderful instrument. The best that I can do is refer to the list of publications related with the observatory.

A view of the main JRO radar (background) from the SOUSY radar (foreground).

The mattress antennas in the foreground, and the digisonde transmitter antenna in the background. Tilted 50 MHz Yagi antennas can also be seen. If you look carefully, you can also see some AMISR panels too. Finally, there is the 4 MW 50 MHz dipole. A story tells that a bird once landed on it while it was hot. The witnesses say that the when the bird flew off, it seemed to be unharmed, until a few seconds later it suddenly just stopped flying and fell to the ground.

High-power large aperture radars

High-power large aperture radars were first envisioned by Bill Gordon (1958) as instruments that can measure the incoherent scatter from free electrons in the Earth's ionosphere. He also proposed that such a radar could be used to observe the Sun and various planetary targets. The first experimental measurements of ionospheric incoherent scatter was soon thereafter reported by Bowles (1958), and many of the other goals were also soon realized when the Jicamarca Radio Observatory and the Arecibo Ionospheric Observatory were built. Both of these radars are still the largest in the world, and have contributed much to our knowledge of Earth's atmosphere and space. The Jicamarca radar located in Peru has a square shaped phased array antenna field with dimensions of 300*300 m. The Arecibo Ionospheric Observatory in Puerto Rico has a spherical dish with a diameter of 305 meters.


Since the early days, many more high-power large aperture radars have been built in various places around the world: These include the Millstone Hill, Svalbard, Tromsø UHF, Tromsø VHF, Kharkiv, Irkutsk, MU, Sondrestrom, PROUST, Poker Flat, and Resolute Bay radars. There are also various large radars of comparable size around the world used for space surveillance purposes. The most recently built Poker Flat and Resolute Bay radars are digital phased array radars, which allow fast beam steering and allow 3D imaging of the ionosphere. The KAIRA receiver array will also be a phased array system, which will function as a bistatic receiver for the Tromsø VHF radar. Some of these radars are shown in the following figure

High-power large aperture radar systems of the world. Photograph credits: Arecibo (NAIC), Jicamarca (JRO), Tromsø (EISCAT Scientific Association), Svalbard (Tony van Eyken), Millstone Hill (MIT Haystack), Kharkiv (Institute of Ionosphere, Kharkiv), Poker Flat and Resolute Bay (Craig Heinsleman).

As the name already suggests, high-power large aperture radars are radars with large antenna aperture and transmission power. As the beam width of an antenna is typically inversely related with the collecting area, these radars also have fairly narrow beams (typically 1 degree). They also typically transmit fairly long coded pulses in order to increase the average transmitted power. In some bi-static planetary radar applications the transmission can be continuous.

While the primary purpose of most high-power large aperture radars is the study of ionospheric plasma, they can also be used for a large variety of other uses, including meteor, space debris, planetary , and lower atmospheric studies.