Tower-Mounted Amplifiers for CALLISTO Receiver and Other Applications
Two low noise amplifier systems are available: The original system is for single or dual installations (TMA-1 and TMA-2, respectively). Depending on the antenna used with this system, the full frequency range 45 ... 870 MHz of the Callisto instrument is available. The newer system (TMA2Q/LPC2Q) is for a dual installation using a linear cross-polarized antenna in the frequency range 50 ... 500 MHz. The LPC2Q power couple assembly used with this system includes a quadrature coupler for deriving circular polarizations from the linear crossed-polarized antennas. Both systems are built, tested and sold in a set that includes the tower-mounted amplifier and power coupler assemblies ready for installation and use.
TMA-1/TMA-2 with LPC
The low noise amplifier system designed for the CALLISTO Receiver consists of a tower-mounted amplifier (TMA) and a low noise amplifier power coupler (LPC). The system is based on the Mini-Circuits ZX60-33LN+ low noise amplifier (LNA) and Mini-Circuits ZFBT-282-1.5A+ bias-tee power coupler modules. Additional details are provided in the block diagram below and following descriptions. Both the TMA-1 and LPC have provisions for an optional second low noise amplifier and can be used with any receiver within the TMA's operating frequency range. It has been tested from10 MHz to 1 GHz but the amplifier is rated to 3 GHz. The p/n TMA-1 includes one low noise amplifier and LPC and p/n TMA-2 includes two low noise amplifiers and LPC. A p/n TMA-1 can be upgraded in the field to p/n TMA-2 by ordering a second amplifier p/n LNA-2. The p/n LNA-2 includes all necessary cables for the upgrade. See also below.
The quadrature low noise amplifier system designed for the CALLISTO Receiver consists of a tower-mounted amplifier (TMA2Q) and a low noise amplifier power coupler with quadrature coupler (LPC2Q). In this system, all RF components are duplicated to provide two independent and identical RF paths to the quadrature coupler. The quadrature coupler derives circular polarizations from two linear cross-polarized antennas. The design of this system is developed from both the LWA Power Coupler LWAPC and original TMA-1/TMA-2. See also below. For additional information on quadrature coupler applications see Antenna Applications of the Quadrature Coupler.
Basic Operation (applies to both the TMA-1/TMA-2 and TMA2Q/LPC2Q)
External power is supplied to the LPC where it is converted to 8.0 Vdc and coupled to the coaxial transmission line to the TMA. At the TMA, the power is decoupled from the transmission line and connected to an internal power supply for the amplifier module. The original TMA-1/TMA-2 has only one powering circuit for both LNAs whereas the TMA2Q/LPC2Q has two powering circuits, one for each LNA.
The low noise amplifier module provides a nominal 20 dB gain (typically 21.8 dB at 50 MHz and 19.1 dB at 900 MHz). The datasheet frequency range of the ZX60-33LN+ amplifier is from 50 to 3000 MHz, but our tests show that its lower frequency extends to at least 10 MHz. In e-CALLISTO applications, the operating range is 45 to 870 MHz except that in the TMA2Q/LPC2Q the range is limited to 50 ... 500 MHz by the quadrature coupler. The TMA-1/TMA-2 has a nominal 1.0 dB noise figure across the e-CALLISTO frequency range. The noise figure of the TMA2Q/LPC2Q as measured at the RF output of the LPC2Q is 2 .. 3 dB higher because the quadrature coupler combines the noise from both amplifiers in the TMA2Q.
The Tower-Mounted Amplifier and LNA Power Coupler assemblies are manufactured, tested and sold as a pair. For ordering information, click here.