Device Development for NASA Space Communications

Novel Power Combiner for Solid State Power Amplifiers

Andrew AbrahamEdwin Wintucky

Communications, Instrumentation, & ControlsElectron & Opto-Electron Device Branch

July 9, 2009

Why Use Microwaves?

• Provides good bandwidth• FCC allocated 30GHz for Deep Space

– Some attenuation from atmosphere

30 GHz

100 MHz

Microwave

Radio

The Need for Space-Based Microwave Communication

• Moon to Earth Communications– Crew Exploration Vehicle– Lunar Lander, Lunar Outpost– Lunar Relay Satellite

• Moon to LEO Communications– Moon to ISS communication– Moon to Tracking & Data Relay Satellite System

(TDRSS)• Deep Space to Earth Communications

– Manned/Unmanned Missions to Mars– Missions to the outer planets

Power Requirements For Space-Based Microwave Communications

• Inverse square law– Mandates 10-15W of power for deep space missions

• Limitations on SSPAs (Solid State Power Amplifier)

– One SSPA can get up to 5-6W

Typical SSPA

How to Increase Power

• Approach 1: Engineer more powerful SSPAs– Problem: Inefficiency (Heat)

• Approach 2: Combine multiple SSPAs– Create a microwave power combiner– 3-way power combining is necessary for current

SSPA technology

Project Goals

• Design and construct testing circuitry to evaluate the performance of: “Novel 3-Way Rectangular Waveguide Hybrid Combiner”

• Characterize the hybrid combiner– S-Parameters– Efficiency– Frequency Response– Phasing

Step 1: S-Matrix Parameters• Network Analyzer

• S-Matrix enables efficiency predictions

S-MatrixInbound Signal

Outbound Signal

Step 2: Construct a 3-Way Circuit

Preliminary Data

Ou

tpu

t P

ort

(N

orm

aliz

ed)

Planned Activities

• Measure efficiency of 3-way combiner• Quantify frequency response • Measure and compare other combining

methods– Multiple 2-way power combiners– Multiple “Magic-T” hybrid couplers– Mix of Magic-T and power combiners

Questions