Antennas

What is the primary function of the receiver in a wireless communication system?

• Generate information to send

• Convert signals into human speech

• Overcome signal modifications and deliver information

• Amplify the transmitted noise

Which of the following is considered multiplicative noise in a wireless channel?

• Thermal noise

• Reflection from smooth surfaces

• Cosmic radiation

• Interference from other transmitters

What are the three types of fading that occur in wireless communication channels?

• Thermal, Doppler, and Rayleigh

• Additive, multiplicative, and subtractive

• Path loss, shadowing, and fast fading

• Refraction, diffraction, and scattering

Which phenomenon causes signal distortion due to the edges of objects like rooftops and hilltops?

• Absorption

• Reflection

• Diffraction

• Refraction

What causes an electric field to be produced in space according to Maxwell’s equations?

• A stationary charge only

• A time-varying magnetic field

• A static magnetic field

• A constant electric potential

What is the direction of the Poynting vector in a plane electromagnetic wave?

• Perpendicular to both the E and H fields

• Parallel to the electric field only

• Along the magnetic field direction

• In the opposite direction of the electric field

What property defines the polarization of a plane electromagnetic wave?

• The direction of the magnetic field

• The magnitude of the wave

• The alignment of the electric field vector

• The Poynting vector amplitude

What type of polarization results from the combination of two orthogonal linearly polarized waves with a 90° phase difference?

• Linear polarization

• Unpolarized wave

• Circular polarization

• Elliptical polarization

What happens to the amplitude of an electromagnetic wave in a lossy medium?

• It increases linearly

• It stays constant

• It diminishes exponentially

• It oscillates unpredictably

What is the unit of the attenuation constant α?

• Volts per meter (V/m)

• Siemens per meter (S/m)

• Meters per second (m/s)

• Inverse meters (m⁻¹)