RF receiver improvements in size, weight, power, and sensitivity are constant goals in the wireless communications community. The combination of phased array antenna systems with high speed analog to digital converters helps engineers meet these goals, because many of the analog components and tasks found in a traditional receive chain are moved into the digital domain. Although the hard work of signal reception is moved into digital signal processing, digital receivers rely on a high performance analog front end to properly condition a signal before analog to digital conversion. In this thesis, two RF front ends are developed for direct sampling L-band phased array receiver applications, which comprise the two main chapters of this document. Both RF front ends are developed on low cost, quick turnaround time PCB materials. Results for system gain and noise figure are presented for each front end. First, the development of an L-band analog front end for a direct sampling GPS phased array receiver is described, with particular attention to gain and noise figure in context of the full system link budget. The RF front end for the GPS phased array receiver meets design expectations by achieving a system gain of 65 dB and a system noise figure of 1.5 dB at the GPS L1 frequency. Second, the redesign and improvement of the Advanced L-band Phased Array Camera (ALPACA) RF over fiber transmitter is documented. New mechanical and electrical design requirements were brought on from the change of target observatory from the collapsed Arecibo obervatory in Puerto Rico, to the Greenbank Observatory in Greenbank, West Virginia. The ALPACA RF over fiber signal transport system with the redesigned transmitter reaches the design expectation of a system noise temperature contribution less than 1 K. Average gain of the RF over fiber system is 49 dB, gain differences between channels are less than 2 dB, and isolation between channels is better than 35 dB. Under optimal conditions, the noise figure of the RF over fiber link is 2.4 dB (213.3 K), which allows for up to 11 dB of attenuation to be added to any given transmit channel to level the gain across all 138 ALPACA channels.



College and Department

Electrical and Computer Engineering



Date Submitted


Document Type





RF over fiber, analog front end, GPS receiver, phased array, Greenbank Observatory



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Engineering Commons