Wireless Fundamentals Lesson 1 Bellevue Community College Bob Young, Instructor

What is a radio wave? Voltage Current Sine Wave Phase Relationships

Radio Wave / RF Energy (a) FCC Frequency Allocations Radiation Propagation Path Loss (distance factors) Path Loss (environmental factors)

Radio Wave / RF Energy (b) Fading (multipath) Fading (Rayleigh) Fresnel Zone Wavelength Diversity Receivers

Fresnel Zone

The formula for calculating the 1st Fresnel Zone is: _____________ F 1 = 72.1  d 2 / (f * D) F 1, = 1st Fresnel Zone radius in feet d = midway distance in miles f = frequency in GHz. D = total distance in miles between antennas Then the 0.6F = F 1 x O.6

How big is the Fresnel zone? For a 5 mile link using 915 MHz 60% of the first Fresnel zone at its widest point (middle of the path) is: feet. For a 5 mile link using 2.4 GHz 60% of the first Fresnel zone at its widest point (middle of the path) is: feet.

Properties of the Fresnel Zone The higher the frequency – The narrower the Fresnel zone.

Properties of the Fresnel Zone The longer the path – The wider the Fresnel zone.

4. Decibels Power Voltage RF Applications Audio Applications

The Gain/Loss Formula dB = 10Log 10 (P out /P in )

Converting dB to Gain Factor GF =10 (dB/10) (Uses the 10 x function on calculator)

5a. Modulation Carrier (definition) Information (definition) Analog Modulation Amplitude Modulation (AM) Frequency Modulation (FM) Pulse Modulation (PM) (ICW)

5b. Amplitude Modulation

5c. Modulation Digital Modulation Frequency Shift Keying (FSK) Phase Shift Keying (PSK) Amplitude Shift Keying (ASK)

6. Transmitter Audio Processor Modulator RF Amplifier

7a. Receiver RF Amplifier (terminology note: misuse of term, “pre-amplifier”) Demodulator (Detector, Discriminator) Audio Processor Pre-emphasis and De-emphasis

7b. AM Receiver

8a. Interference Types of Interference Co-channel Adjacent Channel Intermodulation

8b. Interference Receiver Solutions to Interference Superheterodyne Receivers Image Frequency Dual Conversion Superheterodyne Receivers

8c. Interference Cavity and Filter Solutions to Interference Bandpass Cavities High Pass Filters Low Pass Filters Block Filters Notch Reject Filters LC Filters Crystal Filters

9. Antennas Types Polarization Bandwidth Gain

10. Transmission Line Types Loss Characteristics Bending Radius Pressurized Transmission Line

10a. Other Devices Transmitter Combiner Receiver Multicoupler Splitter Duplexer Leaky Coax Bi-directional Amplifier (BDA) Isolator

11a. Applications & Principles Broadcast Radio Television Microwave Networks Satellite Communications

11b. Applications & Principles RADAR Wireless LAN, Trunked Radio Systems Wireless Data and Internet Telemetry