Chapter 1: Basic Radio Theory

Question 1

Surface Wave (2)
Name, Frequency Range

Answer 1

VLF -> 3 - 30 kHz

LF -> 30 - 300 kHz

Question 2

Skywave (2)

Name, Frequency Range

Answer 2

MF -> 300 - 3000 kHz

HF -> 3 - 30 MHz

Question 3

Spacewave (4)

Name, Frequency Range

Answer 3

VHF -> 30 - 300 MHz
UHF -> 300 - 3000 MHz
SHF -> 3 - 30 GHz
EHF -> 30 - 300 GHz

Question 4

Wavelength Equation

Answer 4

λ = c / f

Question 5

Problems with high and low frequencies

Answer 5

High -> dangerous

Low -> noise

Question 6

Spacewave
How does Spacewave frequency change with sun?
Range equation

Answer 6

Day -> low ionosphere, high frequency
Night -> high ionosphere, low frequency
i.e. frequency follows the sun

Range = 1.23 ( sqrt(stn_H) + sqrt(AC_H)) in nmi

Question 7

Spacewave Refraction Phenomena (2)

Nickname for increased range one

Answer 7

Sub-refraction -> reduced range

Super-refraction -> increased range aka ducting

Question 8

Modulation (4)

Answer 8

Keyed / Pulse
Amplitude - save power (1 sideband enough)
Frequency - high f range, complex, better w/ noise
Phase - very complex (GPS only)

Question 9

Polarisation (3)

polarization direction, antenna direction and oscillation direction

Answer 9

Vertically polarized, V. antenna, V. oscillation
Horizontally polarized, H. antenna, H. oscillation
Circular polarized, C. antenna, C oscillation

Question 10

Antenna

Ideal length, Types (4)

Answer 10

ideal = λ, or .5λ, .25λ...
Omnidirectional - simple wire
Directional - signal leakage on side
Parabolic Dish - highly directional, narrow beam
Slotted Array - best

Question 11

Antenna Location on AC

Answer 11

HF vertical stabilizer
VHF one above, one below body
something below AC for …