Interferometry and Problems in Radio Astronomy

The study of the universe would be extremely limited if the only available frame of reference was visible wavelengths. The waves that we interpret as visible colors only comprise a small portion of the entire radioactive spectrum. However, waves of all electromagnetic frequencies can potentially carry valuable information about the nature of the universe and observable reality. For example, radio frequencies have become useful in a manner of applications including serving as the foundation for an eponymous form of astronomy. Radio waves include those that oscillate at a rate of 3 kHz to 300 GHz and are plentiful throughout the observable universe. An assortment of celestial objects has been identified as sources of radio waves (Chaisson & McMillan, 2011) including stars, galaxies, quasars, and pulsars. The most famous source of radio emissions is the Big Bang and findings from radio astronomy helped to uncover the cosmic microwave background (CMB) which is theorized to have originated from the momentous event.

            Radio astronomy uses a variety of advanced tools and techniques to make telescopic observations of radio waves and their sources. However, despite continual advances in the field, much of the information gathered by these procedures would be lost if not for the application of radio interferometry. Interferometry is a group of techniques that employs the idea to reduce and ideally eliminate the effect of interference in readings of electromagnetic radiation. Interference occurs when waves interact to result in summations, subtractions, and other altered states that obscure the characteristics of the initial waveforms. This is a serious threat to the validity of electromagnetic data on every scale, especially that taken from distant sources as the waves have had more time and space to be altered by interference. Fortunately, the study of waves via interferometry can even account for complex interactions in most cases.

            The most important concept supporting the application of radio or other forms of interferometry is that of superposition, which refers to the combination of waveforms. The results of a vast number of wave interactions provide the framework for the application of interferometry as they allow for the identification and removal of changes to waves that have resulted in the form of those that are observed. Radio interferometry was developed in direct response to the difficulties that arose from excessive interference in radio wave observations that was otherwise only thought to be treatable by increasing the size of radio telescopes to unrealistic levels. Radio telescopes were difficult enough to use due to atmospheric resistance and the need to operate at high elevations. Tools known as radio interferometers were implemented to achieve this task by providing a number of reference points in the form of multiple radio telescopes. This system also provides increased signal volume and resolution, though it does require a large distance between telescopes and thus may face an expansion barrier over time.

            Radio astronomy has become a key part of many astronomical endeavors by providing information from a band of wavelengths that would otherwise remain unavailable for human observation. Like all forms of wave observation radio astronomy is prone to the effects of interference. The study of interferometry provides tools and methods to address this issue by examining the effects of superimposition on the observed waves. These influences can then be removed from the equation to reveal a closer approximation of the original waveform. Giant multi-telescope arrangements known as interferometers are used to collect the required information while advanced mathematic programs are used to determine and reduce the influence of interference on astronomical observations of the radio wave bandwidth.


Chaisson, E., & McMillan, S. (2011). Astronomy: A beginner’s guide to the universe. (6th ed.).             Benjamin-Cummings Pub Co.