Lesson 11 Microwave Antennas

Microwave Antennas

Antennas that operate at microwave frequencies, utilizing line-of-sight transmission for efficient signal delivery.

Horn Antennas

A type of microwave antenna created by flaring the end of a waveguide to improve gain and directivity.

Parabolic Reflector Antennas

Antennas consisting of a parabolic dish with a horn antenna that focuses and directs microwave signals into narrow beams.

Cassegrain Feed Method

A feeding method for parabolic antennas where a horn antenna is placed at the center of the parabolic reflector (back Side) and uses a small reflector at the focal point to direct signals.

Helical Antennas

Antennas formed in the shape of a helix, known for their simplicity and circularly polarized radiation.

Bicone Antennas

Omnidirectional antennas made from two conical sections; they radiate signals in all directions.

Printed-Circuit Board Antennas

Antennas integrated into a printed-circuit board, eliminating the need for separate structures and connectors.

Slot Antennas

Antennas made by cutting slots in metal sheets or waveguides, resembling dipole antennas when appropriately sized.

Dielectric (Lens) Antennas

Antennas made of dielectric material that collimate microwaves into narrow beams, often used in millimeter ranges.

Patch Antennas

Small and inexpensive antennas built on PCBs, characterized by a circular or rectangular copper area.

Phased Arrays

An antenna system composed of multiple antennas used to improve gain and directivity through phase control.

Intelligent Antenna Technology

Adaptive antennas that modify their performance based on electronic decision-making to optimize signal reception and transmission.

Adaptive Beam Forming

Techniques used by antennas to modify their characteristics to focus on specific signals, improving reception in noisy conditions.

Switched Beam Arrays

A type of adaptive antenna system that employs multiple beams to enhance signal quality in cellular systems.

Sectoral Horn

flaring the rectangular waveguide in only one dimension

Pyramidal Horn

flaring both dimensions of the rectangular waveguide

Conical Horn

flaring a circular waveguide

Center-feed (front side) Feed Method:

The energy radiated by the horn (antenna) is pointed at the parabolic dish (reflector,) which focuses the radiated energy into a narrow beam and reflects it toward its destination

Cassegrain feed

The horn antenna is positioned at the center of the parabolic ref

convex

What kind of reflector is used by cassegrain feed

concave

What kind of reflector is used by gregorian feed

helical antenna,

center insulating support is used to hold heavy wire or tubing formed into a circular coil

bicone

One of the most widely used omnidirectional microwave antenna

slot antenna

radiator made by cutting a one- half wavelength slot in a conducting sheet of metal or into the side or top of a waveguide

slot antenna

as the same characteristics as a standard dipole antenna, as long as the metal sheet is very large compared to at the operating frequency. widely used on high-speed aircraft where the antenna can be integrated into the metallic skin of the aircraft

Dielectric or lens antennas

use a special dielectric material to collimate or focus the microwaves from a source into a narrow beam

Patch antennas

made with microstrip on PCBs

Patch antennas

The antenna is a circular or rectangular area of copper separated from the ground plane on the bottom of the board by the PCB’s insulating material

phased array

antenna system made up of a large group of similar antennas on a common plane

ROUND LOOP ANTENNA

a closed loop of pc-board copper connected to the transmitter's or receiver's antenna terminals

inverted-F antenna

a type of antenna used in wireless communication. It consists of a monopole antenna running parallel to a ground plane and grounded at one end

Intelligent antennas or smart antennas

antennas that work in conjunction with electronic decision-making circuits to modify antenna performance to fit changing situations

Adaptive antennas

e systems that automatically adjust their characteristics to the environment

Adaptive antennas

They use beam-forming and beam-pointing techniques to zero in on signals to be received and to ensure transmission under noisy conditions