Day 1: Antennas & Beams

Question 1

A theoretical antenna that radiates energy equally in all directions in the shape of a sphere

Answer 1

Isotropic Antenna

Question 2

Gain is determined by what main elements?

Answer 2

• Directivity
• Efficiency

Question 3

Describes the antennas capability to transmit and receive

Answer 3

Reciprocity

Question 4

In a perfect environment, Tx gain = Rx gain

Answer 4

The Reciprocity Theorem

Question 5

What are the types of gain?

Answer 5

• Active
• Passive
• Computational (AKA coding or synthetic gain)

Question 6

Boosting the signal strength using power

Answer 6

Active Gain

Question 7

Focusing the signal in a specific direction without adding power

Answer 7

Passive Gain

Question 8

Improving signal clarity by using computer processing

Answer 8

Computational Gain

Question 9

Total power leaving an antenna compared to an isotropic radiator

Answer 9

Effective Isotropic Radiated Power (EIRP)

Question 10

What are the radiation lobes?

Answer 10

• Main Lobe
• Side Lobe
• Back Lobe

Question 11

The angular separation between the half-power points on the radiation pattern

Answer 11

Half Power Beam Width (HPBW) (3 dB)

Question 12

One feed point at the base of the antenna radiating out to the sides, but not above or below

Answer 12

Monopole Antenna

Question 13

Made up of two conductive wires or rods, with a feedline in the middle connecting to a transmitter or receiver

Answer 13

Dipole Antenna

Question 14

Optimal for high VHF/low UHF, between 240 to 400 MHz

Answer 14

Yagi-Uda Array

Question 15

What are the elements of the Yagi-Uda Array?

Answer 15

• Driven Element
• Directors
• Reflector

Question 16

Circularly polarized to combat Faraday Rotation and scintillation

Answer 16

Yagi-Uda Array

Question 17

Multiple antenna elements working as a single unit

Answer 17

Array Antenna

Question 18

Acts as a reflecting mirror - reflect energy to the point of reference

Answer 18

Parabolic Antenna

Question 19

Widely used for SHF communications

Answer 19

Parabolic Antenna

Question 20

• Point of reference that gathers the reflected signal
• Focuses signal to amplifier

Answer 20

Feedhorn

Question 21

Receives a large portion of incoming signal, and focuses on one spot

Answer 21

Sub reflector

Question 22

A tunnel that guides radio frequency (RF) waves from one point to another

Answer 22

Waveguide

Question 23

Ensures that the waves travel in a specific direction with minimal loss of energy

Answer 23

Waveguide

Question 24

Physically splits the orthogonal/perpendicular polarities to different ports for Rx/Processing of dual-polarized signals without interference

Answer 24

Orthomode Transducer (OMT)