INTRODUCTION OF ELECTROMAGNETIC WAVES
A wave is defined as travelling oscillations or vibrations. An electromagnetic
wave can travel either in a certain medium or in a vacum. The sunlight and light from other stars
(light is an example of an electromagnetic wave) can reach the earth to indicate the
transportation of an electromagnetic wave in certain medium. However, electromagnetic
(transparent) waves cannot pass through all forms of matter waves. Metals are examples of
medium that blocked electromagnetic waves. Only very thin films or metal are transparent
enough for certain electromagnetic waves, especially a wave with a very small wavelength.
There are several quantities used to specify an electromagnetic wave such as :
Travelling speed : The travelling speed of an electromagnetic wave in a vacuum is the
maximum speed that can be achieved by any objects in the universe.
Frequency : Frequency informs how often an oscillation takes place during a unit
of time.
Wavelength : Wavelegth informs the length of the repetition profile belonging
to the wave.
MICROWAVE
A. Definition of microwave
Micro waves have the highest frequency (Super High Frequency/SHF) which is above 3
GHz ( 3 x 109 Hz) beside on that, micro waves have areas wavelenght with range 10-2 . These
waves can not be seen with our eyes, because the wavelength is very short ( although very small
compared to radio waves ) , and is much larger than the length light waves ( outside the visible
ray spectrum ) . Both are contained in the electromagnetic wave spectrum. Microwaves are one
of which is included in electromagnetic radiation . Electromagnetic radiation in the form of
electromagnetic waves , the wave propagation does not need a medium. Microwave is an
implementation system communication link with a radio transmitter by using short waves
(micro) . This microwave moves in one direction straight line ( one point line-of sight ) and has a
shorter wavelength than the usual communication radio system .
Light wavelength range between 400-700 nm (1 nm = 10-9 m), while the wavelength
range of microwave about 1-30 cm (1 cm = 10-2m).
B. Area / Frequency Range and Wavelength
The wavelength of microwaves about 1 meter until 1 mm or frequency about 300
Mhz until 300 GHz.
In the spectrum of electromagnetic waves , the area of microwave radiation lies between
infrared radiation and radio waves.
C. History amd The Inventor of Microwaves
Radio as ancestors of Microwaves radio early form, it known as "wireless
telegraphy" ( telegraphy without wires ) . This term is obtained because of the time ( circa 1900's
) people assume that the radio is a form of refinement of the telegraph . This technology is used
to send messages from one location to another ( point-to-point ) . Nowadays we know him as a
radio telephony (form of cordless phone) and radio broadcasting (it is a transmission from a base
station to various places in the world).
The use of technology point- to-point and radio broadcasting increasingly widespread .
But the use of radio waves which includes long waves is getting a problem . More and more
radio stations are in operation , the greater the likelihood of wave interference . To avoid this ,
each radio station was given a special frequency to broadcast its programs . But eventually occur
along with the increasing overcrowding radio station which transmits the broadcast.
This prompted investors to enlarge its scope. Large companies began to try to use the
wireless telephony for international relations between the United States and Europe. While doing
research for large projects, they found that for such a wide range of required wavelength shorter
than radio waves that they use. Shorter wavelength also allows the reduction of overcrowding
problem and provide an opportunity for the use of the same frequency for areas located far apart
without interference (because the waves become weaker after a few hundred kilometers). These
waves then known as medium wave (medium waves) . For an example is AM radio waves.
Armed with a variety of sophisticated equipment, the researchers found that the shorter
wavelengths longer able to roam all over the world are better. Short waves has a wavelength of
about 10-100 m. Around 3-30 MHz frequency. This wave allows the transmission from one
location to another location which is in other parts of the world, just by using multiple power
sources Watt (It’s very cheap).
Based on these findings, researchers became more curious. What would be gained if they
could use even shorter wavelength longer than this short waves? That means that the wavelength
is shorter than 10 m and the frequency higher than 30 MHz! Began experiments to obtain ultra -
short waves or microwaves.
D. The Mechanism of Microwaves
Microwaves station works with the help of the antenna , receiver , and other equipment
needed for data transmission communication with microwaves . Microwave signals can transmit
data at speeds up to 45 Mbps , but because of microwave signals is moving in one direction
straight line , then both the transmitter and receiver must be in the line of sight (one-point line of
sight). So, that the center of the microwave installation should be considered of the location and
position to avoid possible interference. Thefore, the microwave stations are often placed on the
tops of buildings, towers, or the mountain.
Microwaves more reflected when on a metal surface or brightly colored. Microwaves can
be through or pass objects/materials having dielectric properties (electric current resistance) are
small. Microwaves are absorbed by objects/materials having large dielectric properties, such as
food and objects that have a dark-colored surface.
Source of Microwaves
1. The sun , although most of the microwaves is blocked by the Earth's atmosphere .
2. Equipment vacuum tubes , it works by using the ballistic motion of electrons in a
vacuum which is influenced by the electric field. This device works in the mode density
modulated . This means that the components had been working on the basis of electron collection
ballistik fly through them , by using a continuous flow.
3. The microwave source that requires little energy as tunnel diodes , Gunn diodes and
IMPATT diodes .
4. Maser , amplifier ( amplifier ) which form a coherent electromagnetic waves caused by
artificial emissions. Maser is a device similar to a laser , which amplifies the light energy emitted
by stimulating radiation . This maser , strengthening the light energy , strengthening the lower
frequencies , the wavelength of the microwave .
D. Application of Microwaves
Utilization of electromagnetic waves is very broad in their daily lives . Utilization of the
electromagnetic waves , especially for telecommunication purposes . Here will be described
specifically on the use of microwaves :
1. Heating
Microwaves have enormous energy , because a very large frequency . It can we know
from the equation E = hf , so that microwaves can generate heat large Yanga . We would be
familiar with the name of a microwave oven that everyday we use for heating food . Microwave
ovens use microwave in about 2:45 GHz frequency band . Basic Principles
Microwave is an electromagnetic wave with a wavelength between 1 millimeter to 1
meter and frequency between 300 megahertz to 300 gigahertz . The oven is a kitchen equipment
that is used for cooking or heating food . The microwave oven is a kitchen equipment that uses
microwave radiation to cook or heat food .
2. Telecommunications
For those who love to take advantage of hotspots is certainly no stranger to WiFi using
ISM frequency band . So also are fond of using bluetooth to transfer files between mobile phones
or computer circuitry . Telecommunications operators also use the microwave for
communication between base stations or between base stations with customers . in Europe,
especially in Germany has rarely seen the use of microwaves for WDM communication method
between the BTS to the BSC . Communication backbone network has been using optical fiber
jarinagn . For communication to the end user in a cellular system still uses microwaves . For in
Indonesia on Tower2 telecom operators are very often encountered directional antennas for
communication between base stations . For communication to end users GSM operators in
Indonesia wear around 800 MHz frequency , 900MHz and 1800MHz .
3. RADAR ( Radio Detection and Ranging )
Radar is the use of microwaves in the frequency range of 3 GHz . Radar is an acronym
for Radio Detection and Ranging . Radar antenna can act as a transmitter and receiver of
electromagnetic waves . Time between the transmit and receive it used to calculate the distance
of the object. radar systems , signal processing plays an important role to reduce interference .
The radar transmits and receives the reflected signal alternately switches the system . Sisem
radar work is applied to the GPS system . Each satellite periodically sends a message that it is
time messaging and satellite orbit information . GPS receiver calculates the distance to each
satellite receiver that sends the message - the message . By comparing the distance between some
of these satellites can be determined the location of the GPS receiver .
INFRARED WAVES
Infrared is electromagnetic radiation whose wavelength is longer than visible light , but
shorter than radio waves radiation. Its name means "below red" (From the Latin infra, "below"),
red is the color of visible light with the longest wavelengths . Infrared radiation has a range of
three "orders" and has a wavelength between 700 nm and 1 mm. Infrared discovered accidentally
by Sir William Herschell, an astronomer at the British empire when he was conducting research
looking optisyang filter material will be used to reduce the brightness of the image of the sun in
the solar telescope.
Infra-red rays can be resulted from electrons vibration in a certain substance, and the
infra-red rays is notexcessively scattered by air particles, therefore can be used to make the
photographs of earth’s surface through the aeroplane or satellite.
Characteristic of Infrared :
Ø Can not seen by human.
Ø Can not pierce untransparent material.
Ø Can produced by komponen yang menghasilkan panas
Ø Panjang gelombang pada inframerah memiliki hubungan yang berlawanan atau
berbanding terbalik dengan suhu. Ketika suhu mengalami kenaikan, maka panjang gelombang
mengalami penurunan.
Jenis-jenis inframerah berdasarkan panjang gelombang :
1. Inframerah jarak dekat dengan panjang gelombang 0.75 – 1.5 µm
2. Inframerah jarak menengah dengan panjang gelombang 1.50 – 10 µm
3. Inframerah jarak jauh dengan panjang gelombang 10 – 100 µm
B. Area / Frequency and Wavelength
