HIRF Demonstrator

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HIRF Demonstrator

• Robert Allen
• Derek Dubbels
• Nathan Engelby
• Mike Ingebrand

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Overview

• Problem Statement
• Description
• Previous Work
• Requirements
• Options Considered
• Block Diagram
• Transmitter Circuit
• Receiver Circuit
• Conclusion

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Problem Statement

• Modern day avionics use a plethora of digital
  electronics, there is a common fear that high
  intensity radiated interference (HIRF) will
  induce noise in the electronics and cause
  equipment failures.
• This project will demonstrate the effects of HIRF
  on a circuit.

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Description

• First we will radiate a dipole antenna contained
  within a model plane with EMI. A measurement of
  the EMI will be taken.
• Then we will inject current from the transmitter
  to the receiver and a measurement of this will be
  taken.

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Previous Work

• The previous group had problems with finding a
  hollow, metal plane.
• A resonant cavity can develop inside the plane
  at a certain frequency, creating stationary
  waves.
• These fields are capable of inducing current in
  the wiring harness of an aircraft that could
  disrupt the operation of its circuits.

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Requirements

• To transmit and measure EMI.
• To design and test a circuit that will transmit
  EMI and a circuit to receive this EMI.
• To make provisions to inject current into the
  planes circuitry.
• To research different methods of EMI (noise)
  measurement.
• To build a complete demonstration unit for all of
  the above requirements.

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Options considered

• Types of antenna to use
• Coiled antenna
• Pancake antenna
• Commercial antenna
• How to measure the EMI
• Toroid
• Peak detector
• Current meter
• Rectify the signal and measure voltage

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Block Diagram
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CW Generator Block Diagram
Power Supply

115 V
Oscillator
Antenna
Amplifier
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Transmitter

• CW Generator
• Field strength of 1 V/m
• Antenna
• YAGI 400-4
• 300 500 MHz (Tuned to 508 MHz)
• Used by previous design group.

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Transmitter
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Receiver

• Dipole antenna tuned to 508Mhz
• 30cm long
• Friis transmission equation
• Pr (Pt GtGr? 2)/(4? R) 2
• Gt is the gain of Tx (Yagi Antenna)
• Gr is the gain of half-wave dipole antenna
• R is the distance from Tx to Rx

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Conclusion

• After many design reviews and redesigns we have
  finally come up with a suitable design for the
  sponsor.
• Construction should begin in the fall.

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Any Questions?