Beacon Design
A notional block diagram of the proposed beacon is shown in Figure 1. This beacon is similar to those described in [1] and [2], the main difference being that the proposed beacon will transmit multiple frequencies (71, 73.5, and 76 GHz) instead of a single frequency. The first step in the beacon signal creation process is to generate stable, low phase noise reference frequencies. This will be achieved by using a common 10 MHz oven controlled crystal oscillator (OCXO) to drive phase-locked dielectric resonant oscillators (PLDROs). An X-band PLDRO will generate the primary The X-band IF reference frequency will be split off into a fundamental signal to be upconverted for transmission and two local oscillator references to be multiplied and used for driving the upconverting mixers. The fundamental X-band signal is split three ways and mixed with three different frequencies – ~20 GHz tones with no offset, a 2.5 GHz offset, and a 5 GHz offset. The resultant Ka-band signals are recombined and amplified. The final step is to upconvert the signals to V-band, pass them into the TWTA, and transmit them through the antenna.
It should be noted that this is a preliminary notional diagram, the final implementation will aim to share hardware between the transponder and the beacon. There will most likely be a diplexer in the Ka-band IF stage before the V-band upconversion to ensure the expensive V-band hardware is shared. When the transponder experiment is being performed, most beacon hardware will be temporarily disabled through the digital hardware and DC bias control. A thorough transponder/beacon integration study will be conducted during Phase 1.
Figure 1. Preliminary block diagram of the satellite beacon payload (click to enlarge).
References:
[1] M. Lucente, T. Rossi, C. Stallo, D. Valente, M. Ruggieri, V. Dainelli, L. Ricci, “Preliminary Design of a Propagation Experiment for a Radio Link Analysis at W Band,” 2008 IEEE GLOBECOM Workshops, Nov 30 – Dec 4 2008.
[2] R. N. Simons and E. G. Wintucky, “Q-band (37-41 GHz) Satellite Beacon Architecture for RF Propagation Experiments,” IEEE Antennas and Propagation Society International Symposium (APSURSI), July 2012.