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Frequency and Phase Locking of Magnetrons Using Varactor Diodes

Award Information
Agency: Department of Defense
Branch: Navy
Contract: N68335-20-C-0822
Agency Tracking Number: N20A-T015-0021
Amount: $239,963.00
Phase: Phase I
Program: STTR
Solicitation Topic Code: N20A-T015
Solicitation Number: A
Solicitation Year: 2020
Award Year: 2020
Award Start Date (Proposal Award Date): 2020-07-17
Award End Date (Contract End Date): 2021-12-15
Small Business Information
690 Port Drive
San Mateo, CA 94404-1111
United States
DUNS: 968627539
HUBZone Owned: No
Woman Owned: No
Socially and Economically Disadvantaged: No
Principal Investigator
 Michael Read
 (802) 223-9855
Business Contact
 Lawrence Ives
Phone: (650) 312-9575
Research Institution
 SLAC National Accelerator Laboratory
 Lili Ma
Menlo Park, CA 94025-0000
United States

 (650) 926-5549
 Federally Funded R&D Center (FFRDC)

Magnetrons are compact, inexpensive, and highly efficient sources of RF power used in many industrial and commercial applications. For most of these applications, the requirement is for RF power without regard to precise frequency or phase control, and noise riding on the RF signal is not important. For many accelerator, defense, and communications applications, however, these characteristics prevent use of magnetrons. It is possible to control frequency, phase, and noise by locking the output to a reference RF signal directed into the magnetron output. This requires a circulator to protect the RF source providing the locking signal. Unfortunately, circulators are large, often expensive component that prevents installation in compact or mobile applications. This program proposes to use varactor diodes to frequency and phase lock the magnetron RF power. The program will investigate two approaches. The first approach is to insert reactive components into the magnetron resonant structure to convert the magnetron into a voltage-controlled oscillator. The fast tuning speed of the varactor diode will provide rapid frequency tuning offer a significant bandwidth. The requirement is to use a varactor that can tolerate the high RF frequency and power loading. This approach incorporates simple hardware with high loop bandwidth and lower cost than previous investigations. No RF power is required to lock the magnetron, and no circulator is required. The second approach incorporates varactor diodes into a cavity coupled to the external waveguide that generates a controlled reflection toward the magnetron. The advantage of this approach is that no modifications are required to the magnetron with the mechanical and electrical issues that entails. The Phase I program will simulate performance in an S-Band magnetron currently in production. The program will investigate mechanical issues associated with integrating the diode into the RF circuit to provide the required performance, and perform experiments to test the external cavity approach. If the results demonstrate feasiblilty, it will be proposed to build and test a varactor controlled, S-Band magnetron producing more than 5 MW CW in the Phase II program.

* Information listed above is at the time of submission. *

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