Terrestrial Non-Physical Transmission Media

Lecturer Ir. True Prayudi

Terrestrial derived from the word terra: Earth

Non Terrestrial Transmission Media is physical transmission medium in the form of radio waves propagation are not much or as if parallel to the earth (not including satellite transmission)

The use of radio waves as the transmission medium is usually determined by the frequency / wavelength

Frequency is the number of vibrations that pass a certain point in a different time interval

Unit of frequency mentioned: according to the inventor of the electromagnetic wave Heartz: Heinrich Hertz (Germany)

This frequency is inversely proportional to the wavelength corresponding to the formula:

Frequency = -----

                       wave

Types of frequency:

Middle Frequency (MF): 300-3000 KHz

High Frequency (HF): 3-30 MHz

Very High Frekeunsi (VHF): 30-300 MHz

Ultra High Frequency (UHF): 300-3000 MHz

Super High Frequency (SFH): 3-30 GHz

Extremely High Frequency (EHF): 30 - 300 GHz

The quantity of each type of radio frequencies is called Radio Frequency Spectrum

MF (Middle Frequency) is called by radio to the wavelength being. Widely used in commercial private radio broadcasting

HF (High Frequency) is called a short wave radio system, which is widely used for connection to a distant place / remote.

VHF and UHF so-called short-wave system, widely used for the benefit of close relationships.

SHF and EHF called microwave systems. In Indonesia to be used by Telkom and satellite tererstrial

HF Radio Transmission System

HF radio waves are typically used for long-distance relationship as the relationship between islands. With this system one can use to saluraan 4 conversations at once without disturbing each other.

HF radio waves propagate through the air and then reflected back to earth through the layers of the ionosphere. Distance of two terminals can reach more than 1500 km for a single hop.

This system is very far-reaching power but require a strong transmit power so that it takes a lot of power resources. Therefore, it usually does not operate 24 hours

Radio Transmission Systems VHF / UHF

VHF system works at a frequency of 30-300 MHz, and UHF frequency 300-3000 MHz.

VHF system is connected by way of line of sight (each mirror), meaning that both places have meant to each other to see each other without any barrier.

Ducts UHF system has a capacity greater than VHF. In our country the system is used for connecting Surabaya to Banjarmasin tropocaster through. Tropocaster called because of the emission line wavelength emitted by the troposphere (the lowest of our earth's atmosphere).

SHF Radio Transmission Systems

This system is commonly referred to as system Microwave (Microwave). Called the microwave because it uses a very short wavelength. The system is only reaching 50-70 km, so that the necessary repeater-repeater to connect.

Example: Microwave Terminal Jakarta - Medan with a distance of 2300 km repeater requires a total of 56 pieces.

In Indonesia, the archipelago has a Microwave Systems, which include:

Microwave Trans Sumatra

Microwave Java - Bali

Micro wave of Eastern Indonesia

Advantages and Disadvantages

HF Radio Waves

Excess

Can reach distances Kauh

Can pass through the sea, desert, desert, jungle,

Can cross-prone areas

Capacity greater than the physical channel

Shortage

Can not operate for 24 hours

Easily distracted by the weather

The quality of conversations can be less reliable

Small capacity

Microwave

Excess

Ducts are large compared to the ability of HF

High reliability is not affected by weather

Allows long distance conversation disalurkannya

High Flexibility

Repeaters can be controlled not need to be maintained by technical personnel

Shortage

Shorter range than the HF

Requires a lot of repeater channels

Repeater locations are often remote and difficult to obtain

Requires proper research site long and difficult

Wave propagation easily influenced by the mountain