To compliment our standard radio training, we also offer High Frequency Base Station Installation training, below are examples of this course

Aim:

  1. Enable participants to gain an understanding of the requirements and practical considerations for installing a base station HF system

Objectives:

    1. To understand the basics of
      • A fixed base station
      • The propagation direction of an antenna
      • Antenna take-off angles
      • Antenna mounting height and effects of frequency change
      • Installing an antenna and site selection
      • Antenna earthing

Antenna testing

A fixed base station consists of:

  • Transceiver
  • Antenna
  • Power Supply

Topics covered include:

  1. Installation of a fixed antenna
  2. Installation of a transceiver
  3. Testing the base station installations

Proper setup of the system ensures the quality of communication!

Important facors to consider when setting up an antenna:

  1. Propagation direction
  2. Distance of communication
  3. Grounding
  4. Antenna support structure
  5. Antenna site selection
  6. Installation of an antenna tuner

Antenna Propagation

  • Depends on antenna type – horizontal or vertical antenna
  • Horizontal antennas have complex radiation patterns, which depend on factors such as height and frequency. E.G, Diople, broadband and long wire antenna
  • Vertical antennas have omni-directional radiation patterns (equal radiation strength in all direction). Hence direction of antenna face is not important, e.g. vertical whip antenna

Distance of Communication

  • Operating Frequency
  • Take-off Angle
  • Transceiver Power

Distance vs Frequency

  • Shorter distances require lower frequencies
    • Larger antenna size
  • Longer distances require higher frequencies
    • Smaller antenna size
  • Size of antenna is inversely proportional to frequency

600-12004-118m x 38m1200-15005-186.5m x 31m2500-100007-285.5m x 26m

Approximate Path Length (km) Frequency Range (MHz) Antenna Mounting Dimension
0-300 2-6 13m x 58m
300-600 3-8 10m x 47m

What is take-off angle?

Elevation plot of the antenna radiation pattern

Take Off Angle Graph

Distance vs Take-Off Angle

Distance vs Take-Off Angle

  • Shorter distances require higher take-off angles
    • Antenna is installed lower
  • Longer distances require low take-off angles
    • Antenna is installed higher
  • Take-Off angle various by how high the antenna is mounted
Take-Off Angle (degrees) Day Time (km) Night Time (km)
0 3000 4500
10 1900 2900
25 1000 1600
40 550 1000
60 250 450
70 150 300
80 80 150

Height of a Fixed Antenna

Height of an antenna can be expressed in terms of physical height, H or wavelength

Height of Fixed Antenna Graph

Height of Fixed Antenna Graph

Controlling Take-Off Angle

For a fixed phjysical height, varying the operating frequency will effect the radiation pattern and hence vary the take-off angle.

For a fixed frequency, varying the physical height of an antenna will also effect the radiation pattern and hence vary the take-off angle.

Controlling Take Off Angle Graph

Controlling Take Off Angle Graph

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