94 GHz Switching Circulator Tracy Shain Ryan Nichols Daniel Komisar Andrew Gadbois Advisor: Prof. Paul Siqueira

Develops microwave components from GHz in satellite and millimeter wave communication Industry leader in millimeter wave communication Corporate headquarters in Northampton, MA Complete in-house machining and fabrication Allowing full facility access and use of high frequency equipment

What is a Circulator?

Example System: Continuous Transmission

Example System: Continuous Transmission with Receiver Protection

Circulator (RF Switch)

Why W-Band? ● Better resolution for remote sensing ● Smaller ● Higher bandwidth as percentage of center frequency

Design Responsibilities RF Design and Simulation Tracy Shain ResearchDaniel Komisar RF Measurements and Tuning Ryan Nichols Design of Driver Circuit Andrew Gadbois

Deliverables ● Design plans – Junction schematics from HFSS simulation – Driver circuit schematics from simulations – Material and spacial tolerances ● Test results/Final specs ● Empirical tuning instructions ● 94 GHz switching circulator

Specifications ● Bandwidth: 3% ● Center Frequency: 94 Ghz ● Isolation: 20 dB ● Insertion loss: 0.8 dB ● VSWR: 1.3:1 ● Switching Time: 10 ns ● Temp: -40°C – 85°C ● Driver circuit CMOS/TTL compatible

Design Alternatives Types of Switches:  Ferrites  PIN Diode  Mechanical Transmission: Waveguide Microstrip

Design Alternatives Types of Latching: No Latching Requires constant power to maintain magnetic fields Eg. Electromagnet with no field when there is no current Half - Latching Constant field in one direction, but requires constant power to reverse field Fully - Latching Short pulse of current in one direction is capable of rearranging the fields within the ferrite to reverse the direction of the magnetic field

Critical Analysis of Failure ● Insertion loss ● Frequency response ● Power handling ● Input/output impedance ● VSWR ● Magnetic Leakage

Schedule TaskSept.Oct.Nov.Dec. Research********************* RF Design************* Model 1******** Model 2******** Sim 1*** Sim 2*** Research Ferrite******* Order Ferrite********* Driver Design****************

Schedule TaskWeek 1Week 2Week 3Week 4 Driver Design*********** Layout Driver***** Order Parts***** Order Boards****** Assemble Driver***** Build Circulator********** January

Schedule TaskFeb.Mar.Apr. Test Circulator and Driver ********** Redesign / Tune Ferrite ********* Documentation and Report **********

MDR Specifications ● Complete Ferrite research ● Order material to allow sufficient lead time ● Complete microwave design and numerical tests - Ansoft Design and Simulation - Analyze 2 Design Alternatives - Test 94 Ghz Y-Junction Waveguide ● Preliminary Driver Design

Questions?