Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Foundation Ham Radio Licence > 4. Feeders & Antennas > Flashcards

4. Feeders & Antennas Flashcards

1
Q

what are feeders used for?

A

Connecting the transmitter/receiver to the antenna?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What happens to feeders on transmit and receive?

A

Feeders exhibit ‘loss’ on transmit & receive.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

T/F The longer the cable, the less amount of loss experienced?

A

FALSE: More loss is experienced the greater the length of the cable.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why does loss occur?

A

Loss occurs as some of the RF energy is converted to heat.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What else affects feeder loss?

A

Frequency.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What kind of feeder is recommended for VHF & UHF ?

A

Thicker, low-loss feeder cable is recommended.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the two types of feeder?

A

Coaxial & Twin Feeder (Ladder-lined)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Which kind of feeder is more commonly used by amateurs, Coaxial or Ladder Line?

A

Coaxial.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

T/F: Twin Feeder Cable is balanced.

A

TRUE. Twin Feeder is balanced, Coaxial Cable is unbalanced.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

T/F: Twin Feeder has two wires for equal and opposite signals

A

True. This is why its balanced.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What keeps the signal within coaxial cable?

A

The Outer braid (screen)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How many types of connector are there?

A

Four.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What connector is commonly used for HF?

A

PL259

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the N Connector commonly used for?

A

VHF & UHF

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the one type of connector which is not screw thread locking?

A

BNC - It is bayonet locking.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What connector is common for handheld radios?

A

SMA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What Ohm BNC connector is used and why?

50 or 70

A

50 Ohm - the 75 Ohm is not used as it has a different type of pin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What do antennas do?

A

Convert Electrical Signals into Radio Waves (and vice-versa)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

T/F: Antennas are designed for specific frequencies.

A

TRUE. They are also different sizes depending on the band.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

In general, Lower Frequencies (Longer Wavelengths) require…..?

A

Larger Antennas.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Name 3 of the 5 antenna types.

A
  • Yagi
  • Dipole
  • 5/8 Wave
  • 1/4 Wave
  • Long Wire
22
Q

Is a Dipole a balanced or unbalanced antenna?

A

Balanced.

23
Q

How long (in Wave Lengths) is a Dipole Antenna?

A

Half a Wavelength.

24
Q

How long would a dipole antenna need to be to work in 14Mhz?

A

14Mhz is the 20 metre band, so 10 metres, as it is half a wavelength long.

25
Q

What does a Polar Pattern show?

A

A polar pattern shows how RF signals radiate from the antenna.

26
Q

Where are Omni-Directional signals directed?

A

Omni-Directional signals are directed in all directions.

27
Q

What type of Antenna is Omni - Directional?

A

Dipole

28
Q

How long must a 1/4 wave Ground Plane Antenna be to work at 144Mhz (2m Band)

A

50cm Long

29
Q

What forms the ground plane on a antenna?

A

4 Horizontal Wires

30
Q

What are the 4 horizontal wires are used as the ground planes called?

A

Radials

31
Q

What do the radials do?

A

They form a ground plane which act as a mirror for radio signals.

32
Q

How long is a 5/8 Wave Ground Plane Antenna?

A

A 5/8 of a wavelength

33
Q

Where do you get a better signal Ona 5/8 wavelength antenna?

A

Towards the Horizon.

34
Q

Why is there a coil at the base of a 5/8 Wave Antenna?

A

It is for Coax Matching.

35
Q

What is 5/8 Wave Antenna often used for?

A

VHF & UHF Mobile.

36
Q

What is a End-Fed Antenna?

A

A Basic Long-Wire Antenna

37
Q

Are end-fed antennas likely to be of the correct length?

A

No. They will need to be matched.

38
Q

Are End Fed Antennas more or less likely to cause interference (EMC) than other types?

A

More Likely

39
Q

What type of Antenna is directional?

A

Yagi

40
Q

How many directions are signals from a Yagi directed in?

A

Mainly One

41
Q

What are the components of a Yagi Antenna?

A

A Dipole, with reflectors and several directors.

42
Q

Yagi Antennas have a …….. gain than other antennas.

A

Higher

43
Q

What is gain measured in?

A

Decibels (dB) (Relative to a high wave dipole).

44
Q

Define ERP

A

Effective Radiated Power

45
Q

What is the ERP Calculation?

A

ERP (Watts) = transmitted power x gain

46
Q

What is the ERP?

A

The directional power of an antenna.

47
Q

How can a antenna be polarised?

A

Either Horizontally or Vertically

48
Q

Can Yagis be Horizontally or Vertically Polarised?

A

BOTH. Yagis can be polarised either way.

49
Q

What way are VHF & UHF antennas generally polarised?

A

Vertically.

50
Q

Should the antennas be polarised the same way for VHF & UHF?

A

Yes. The antennas must be polarised the same way for VHF/UHF.

51
Q

Why does HF polarisation matter less?

A

It matters less as polarisation for HF as it may be changed by the Ionosphere.

Foundation Ham Radio Licence (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions