Microwave antenna

It is defined as the ratio of power per unit area received from the antenna at a point in space to the power received from an isotropic antenna at the same point in space.

ANTENNA GAIN

• It is defined as the ratio of power per unit area received from the antenna at a point in space to the power received from an isotropic antenna at the same point in space.
• The capability of a directive antenna to concentrate power in a given direction is the capability to direct radio frequency energy into a given region and not in all direction.
• For transmitting antenna, it refers to how far is the concentration of transmission power in a given direction.
• For receiving antenna, it refers to how far its receive the best signal in a given direction rather than in all direction.

To convert the spherical waveform produced at a focus point to the plane wave.

CHARACTERISTIC OF PARABOLOID ANTENNA

• To convert the spherical waveform produced at a focus point to the plane wave.
• All the energy received from the free space which is the same as the parabolic axis (Rx) will be reflected to the focus point.

ADVANTAGES

• The gain can be increased whenever needed.
• Can be operated at any frequency in the microwave zone.
•  Simple Installation.

DISADVANTAGES

• Difficult to install with high accuracy.
• Operational frequency limited to the types of dish used.

GAIN ; G = 4 π A

GAIN

GAIN ; G = 4 π A

λ2

Where;

G = gain;

A = area of parabolic dish (m2);

λ = wavelength of operational frequency (m)

If the area of the dish, A

A = π d 2

4

Where;

A = area of parabolic dish (m2);

d = diameter of dish opening (m)

Beamwidth α = 115 λ °

d

α = antenna beamwidth or angle between half power points ( °)

λ = wavelength (m)

d = diameter of dish opening (m)