Ch2 Fundaments

Question 1

amplitude

Answer 1

the strength of a radio wave; continuously varies

Question 2

oscillating

Answer 2

the continual change of the signal’s amplitude; the signal goes up and down as it oscillates

Question 3

cycle

Answer 3

as the signal oscillates, each complete up-and-down sequence forms a cycle

Question 4

frequency (f)

Answer 4

the number of cycles per second; represented by the lower-case f

Question 5

hertz (Hz)

Answer 5

unit of measurement for frequency

Question 6

period (T)

Answer 6

the period of the cycle (represented by capital-T) is its duration

Question 7

reciprocal of the period 1/T

Answer 7

frequency is the reciprocal of the period; f = 1/T

Question 8

harmonic

Answer 8

a signal with a frequency that is some multiple (x2, x3, x4 and so on) of a fundamental frequency; 2f is second harmonic etc

Question 9

phase

Answer 9

position within a cycle; phase is used to compare how sine wave signals are aligned in time

Question 10

degrees

Answer 10

used to measure a phase; there are 360 degrees in a sine wave

Question 11

out of phase

Answer 11

if two sine waves have a phase difference of 180 degrees, one wave is increasing, the other decreasing

Question 12

in phase

Answer 12

waves that have no phase difference and are increasing/decreasing at the same time

Question 13

audio frequency (AF signals)

Answer 13

signals below 20 kHz that humans can hear

Question 14

radio frequency (RF signals)

Answer 14

signals above 20 kHz (everything above what humans can hear)

Question 15

radio spectrum

Answer 15

the range of radio signal frequencies: 20 kHz - several hundred GHz

Question 16

band

Answer 16

a specific range of frequencies in which signals are used for a common purpose or have similar characteristics

Question 17

AM band

Answer 17

535 - 1700 kHz

Question 18

FM band

Answer 18

88 - 108 MHz

Question 19

amateur bands (ham bands)

Answer 19

VHF 30 - 300 MHz; UHF 300 MHz - 3 GHz; HF (Shortwave) 3 - 30 MHz

Question 20

spectrum display

Answer 20

organizes signals according to their frequencies and signal strength

Question 21

wavelength (λ)

Answer 21

the wavelength of a radio wave is the distance that it travels during one complete cycle; represented by the Greek letter lambda

Question 22

speed of light (c)

Answer 22

all radio waves travel at the speed of light; represented by the lower-case c; the speed of light is constant at 300,000,000 or 3 x 10⁸ meters per second

Question 23

wavelength/frequency relationship

Answer 23

λ = c / f Because the speed is constant, wavelength and frequency have an inverse relationship

Question 24

amateur bands as wavelengths

Answer 24

Ex: “I’ll call you on 2 meters. Let’s try 146.52 MHz.” The frequency band is referred to as 2 meters because the radio waves are approximately that long.

Question 25

wavelength of a 1 MHz radio wave

Answer 25

λ = c / f; λ = 300 Meters per second / 1 MHz

Question 26

wavelength of a 1 MHz radio wave

Answer 26

λ = c / f; λ = 300 Meters per second / 1 MHz = 300 meters

Question 27

convert from meters to feet

Answer 27

multiply the wavelength in meters by 3.28

Question 28

convert from feet to meters

Answer 28

divide the wavelength in feet by 3.28

Question 29

convert from meters to inches

Answer 29

multiply the wavelength in meters by 39.37

Question 30

three basic elements of an amateur station

Answer 30

transmitter (XMTR), receiver (RCVR), and antenna

Question 31

transceiver (XCVR)

Answer 31

AKA “rigs”; combines all three basic elements in one piece of equipment

Question 32

feed line

Answer 32

AKA “transmission lines”; connects the antenna to the transmitter or receiver

Question 33

transmit-receive (TR) switch

Answer 33

allows a transmitter and receiver to share a single antenna

Question 34

repeater

Answer 34

located on high buildings or towers, a receiver and transmitter that will re-transmit the information from a received signal simultaneously on another frequency or channel; provide communications between low-power mobile and portable stations

Question 35

duplex communication

Answer 35

the process repeaters use to re-transmit information simultaneously; instead of a transmit-receive switch, it uses a duplexer