To Design and Build a Portable, Miniaturised, Multichannel FM Transmitter

Submitted in part requirement for final year project to the University of Limerick, Limerick, Ireland, 24/04/98

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Abstract Declartion, Acknowledgements & Dedication.

Table of CONTENTS :

• 1.1 Introduction
• 1.2 Technical Background
• 1.2.1 Radio Frequency and Wavelength Ranges
• 1.3 Fm theory
• 1.3.1 Derivation of the FM voltage equation
• 1.3.2 Angle modulation Graphs
• 1.3.3 Analysis of the above graphs
• 1.3.4 Differences of Phase over Frequency modulation
• 1.4 Technical terms associated with FM
• 1.4.1 Capture Effect
• 1.4.2 Modulation Index
• 1.4.3 Deviation Ratio
• 1.4.4 Carrier Swing
• 1.4.5 Percentage Modulation
• 1.4.6 Carson’s Rule

• 2.1 Resistor
• 2.2 Inductor
• 2.3 Capacitor
• 2.4 Resonant Circuits
• 2.4.1 Series resonant circuit
• 2.4.2 Parallel resonant circuit
• 2.5 The Q factor
• 2.6 High frequency response of discrete components
• 2.6.1 Wire
• 2.6.2 Inductor
• 2.6.3 Capacitor
• 2.7 Temperature stability of the Tank
• 2.8 Discrete components to be considered for use in a High frequency circuit
• 2.8.1 Resistors
• 2.8.2 Capacitors
• 2.8.3 Inductors
• 2.9 NPN Transistor
• 2.9.1 High Frequency Response
• 2.10 Transistor Amplifiers
• 2.10.1 Common Emitter
• 2.10.2 Common Collector (emitter follower)
• 2.10.3 Common Base

• 3.1 Introduction
• 3.2 General Overview
• 3.1 Exciter /Modulator
• 3.2 Frequency Multipliers
• 3.3 Power output section
• 3.3 The Microphone
• 3.4 Pre-emphasis
• 3.5 The Oscillator
• 3.6 Reactance modulator
• 3.7 Buffer Amplifier
• 3.8 Frequency Multipliers
• 3.9 Driver Amplifier
• 3.10 Power Output Amplifier
• 3.11 Antenna
• 3.11.1 Radiation Resistance
• 3.11.2 Power transfer
• 3.11.3 Reciprocity
• 3.11.4 Hertz Dipole
• 3.11.5 Monopole or Marconi Antenna
• 3.12 Impedance matching

• 4.1 Introduction
• 4.2 Phase locked loop
• 4.3 Stand Alone VCO
• 4.4 Two transistor Design
• 4.5 One transistor design

• 5.1 Introduction
• 5.2 Final Circuit Design
• 5.3 Oscillator analysis
• 5.4 Components List
• 5.4.1 Resistors
• 5.4.2 Capacitors
• 5.4.3 Inductor
• 5.4.4 Transistors
• 5.4.5 Microphone
• 5.4.6 Input - Out connections
• 5.5 Construction and assembly
• 5.5.1 Pcb Layout
• 5.6 Antenna Considerations
• 5.7 Overall frequency of the transmitter

• 6.1 Introduction
• 6.2 Equipment used
• 6.2.1 Spectrum Analyser
• 6.2.2 Frequency Meter
• 6.2.3 Radio Receiver
• 6.3 Spectrum Analyser test
• 6.4 Power Output

• 7.1 Introduction
• 7.2 Report Overview
• 7.3 Discussion
• 7.4 Conclusions
• 7.5 Recommendations

Appendix A Mathcad Work

Appendix B Q2N3904 (NPN)

Appendix C MC1648 (VCO)

Appendix D PP3 (9V Battery Specs)