Low Noise Amplifiers

A number of low-noise amplifier modules are used for RFI monitoring, and emission characterization measurements. Each amplifier module is constructed using a combination of individual amplifiers, each cascaded, to give significant gain, dependent upon the application. The individual amplifiers are housed in a ruggedised metallic case, to ensure survival out in the field, and to provide a thermal mass, for heatsink purposes. The amplifiers being:

UHF Module: 100-1000MHz, cascaded gain=50dB. This module comprises of 2xMiteq AM-2A-000110 amplifiers, with a 1dB compression point (C.P.) of +8dBm, and a noise figure (N.F.) of 1.2dB

L-Band Module: 800-2000MHz, cascaded gain=55dB. This module comprises of 1xMiteq AFS3-00950175-05-13P-6 amplifier with a 1dB C.P. of +15dBm, and a N.F. of 0.5dB,
followed by 1xAvantek AFT-2032 (500-2000MHz) amplifier with a 1dB C.P. of +13dBm, and a N.F. of 3.5dB

Broad-Band Module: 400-4000MHz, cascaded gain=30dB. This module comprises of 1xMiteq AFS3-00400350-12-10P-4 amplifier with a 1dB C.P. of +15dBm, and a N.F. of 1.1dB

Image rejection and out-of-band spurious signal rejection is through the use of a number of K&L Tunable Bandpass Filters, these being:

5BT-250/500-5-N/N: 250-500MHz, 5% 3dB BW, 5-section filter
5BT-500-1000-5-N/N: 500-1000MHz, 5% 3dB BW, 5-section filter
5BT-1000/2000-5-N/N: 1000-2000MHz, 5% 3dB BW, 5-section filter

In addition, some pre-selection filtering between the antenna output, and the input to the high gain LNA modules (UHF & L-Band), is required. This filtering reduces the significant power levels associated with the analogue and digital TV transmissions (550-640MHz) from Mt Canobolas, over a 100km away from the observatory