Introduction to Antenna

1. ANTENNAS AND MICROWAVE ENGINEERING
MICROWAVE FREQUENCY
BANDS
⚫ Specific range of frequencies in RF spectrum.
⚫ Range:1 GHz to 1000 GHz & λ: 30 cm to 0.03 cm.
⚫ Applications: military and civilian sectors.

2. ANTENNAS AND MICROWAVE ENGINEERING
MICROWAVE FREQUENCY
BANDS

3. ANTENNAS AND MICROWAVE ENGINEERING
MICROWAVE FREQUENCY
BANDS

4. ANTENNAS AND MICROWAVE ENGINEERING
What is the origin of the antenna?
⚫ Faraday (1830): Coupling of electricity and magnetism and showed a definitive relationship
⚫ Heinrich Hertz (1836): Forced an electrical spark to occur in the gap of a dipole antenna.
⚫ Marconi (1901): Sending information across the Atlantic. For a transmit antenna, he used
several vertical wires attached to the ground.
⚫ Columbia University (1906) had an experimental wireless station where they used a
transmitting aerial cage.
⚫ Yagi-Uda Antenna (1920), Horn antennas (1939), Antenna Arrays (1940), Parabolic Reflectors
(1950), Patch Antennas (1970), PIFA (1980).
⚫ Important component in any wireless communication system.
PHYSICAL CONCEPT OF RADIATION

5. ANTENNAS AND MICROWAVE ENGINEERING
• An antenna is an electrical conductor or system of conductors
– Transmission - radiates electromagnetic energy into space
– Reception - collects electromagnetic energy from space
• In two-way communication, the same antenna can be used for transmission and reception
• An antenna is a circuit element that provides a transition from a guided wave on a transmission line
to
a free space wave
• It also collects electromagnetic energy from space
• In transmit systems the RF signal is generated, amplified, modulated and applied to the antenna
• In receive systems the antenna collects electromagnetic waves that are “cutting” through the antenna
and induce alternating currents that are used by the receiver
PHYSICAL CONCEPT OF RADIATION

6. ANTENNAS AND MICROWAVE ENGINEERING
STONE AND POND ANALOGY FOR WORKING OF A TRANSMITTING
ANTENNA

7. ANTENNAS AND MICROWAVE ENGINEERING
BOAT ANALOGY FOR WORKING OF A RECEIVING
ANTENNA

8. ANTENNAS AND MICROWAVE ENGINEERING
WORKING OF A RECEIVING
ANTENNA

9. ANTENNAS AND MICROWAVE ENGINEERING
NEAR- AND FAR-FIELD
REGIONS
• Space surrounding an antenna
• Changes of antenna amplitude pattern shape