Interference Protection Group (IPG)

In order to conduct various tests needed to detect any probable causes of noise in the antenna?s output signals, we use many different types of equipment. Some of the equipment used for recording data are Vector Network Analyzers, Spectrum Analyzers, and signal generators. Another crucial piece of equipment which makes testing easier is the reverberation chamber, which is described in more detail below. Within the reverberation chamber is the Pomeroy antenna which is also described in more detail below. Synthesized signal generators are used during shielding tests to provide a calibrated test signal.

The picture shown in the upper right is of the reverberation chamber; the chamber's dimensions are 4.9m x 11m x 3m. The Pomeroy is located in the background and is being used to test the VLBI Digital Backend Prototype's emissions. The aluminum covered Styrofoam boards located behind the VLBI are used as reflectors to prevent direct path radiation from striking the receiving antenna.

The second and third pictures shown to the right are that of the Pomeroy, an antenna designed using the program High Frequency Structural Simulator (HFSS) and built by Jesse Pomeroy in the summer of 2007. The Pomeroy is an ultra wide band (UHF-18 GHz) biconical dipole. The Pomeroy along with Spectrum Analyzers, are used to record the RF power generated by the digital and RF objects being tested. The Pomeroy is used to test the emissions on new equipment such as EVLA converter modules, new monitors, PCs and cameras. The Pomeroy is also used in the testing of shielded racks and enclosures.

The Reverberation Chamber. The equipment (VLBI DBE) in the front is being tested for emissions.

The Pomeroy, an antenna designed and built by Jesse Pomeroy in the summer of 2007.

The Pomeroy's feed point.