Gujarat Technological University

Birla Vishvakarma Mahavidhyalay Electronics & Telecommunication Department

Topic :- Microwave Antenna

S U B M I T E D B Y : - P R A S I D D H M A K A D I YA : 1 3 0 0 8 0 11 2 0 2 9A PA R T R I V E D I : 1 3 0 0 8 0 11 2 0 5 7VAT S A L B O D I WA L A : 1 4 0 0 8 3 11 2 0 0 2

Under the Guidance Prof. K.R.PatelET Department,

BVM.

Outlet :-

Definition Classification On Microwave Antenna Working of Microwave Antenna

Definition :-

All Antenna operated under the microwave frequencies are called as microwave antenna.

When the frequency of operations is above 30 MHz, straight line (LOS) Propagation will be preferred .

Planner waveform are preferred for straight line communication in order to increase the directivity & to receive more power with least distortion.

The Various Antenna Used at Microwaves

1. Microstrip Antenna 2.Horn Antenna 3.Parabolic Reflector 4.Lens Antenna 5.Slot Antenna

Horn Antenna

Horn antenna are described as flared Waveguide which gives good amount of gain over broad range of microwave frequencies.

These can be either of rectangular or circular in shape. Normally they are probe fed antenna.

Figure of Horn Antenna

Application

Horn antennas are extensively used at microwave frequencies when the power gain needed is moderate. For high power gains other antennas like lines or parabolic reflectors etc are preferred rather than horn antennas.

Microstrip Antenna

Microstrip antenna are planner version for microwave antenna. they are light in weight & small in size.

These are narrow bandwidth structure. The microstrip antenna in array from are very famous structure to obtain high gain with narrow beam.

Electronics beam Scanning is much easy with Microstrip Antenna.

Fig of Microstrip antenna

Application :-

1)Global Positioning Satellite

2) Paging

3) Cellular Phone

4) Personal Communication System.

Parabolic Reflector

A parabolic antenna is an antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves. The most common form is shaped like a dish and is popularly called a dish antenna or parabolic dish.

The main advantage of a parabolic antenna is that it has high directivity. It functions similarly to a searchlight or flashlight reflector to direct the radio waves in a narrow beam, or receive radio waves from one particular direction only.

Parabolic antennas have some of the highest gains, that are they can produce the narrowest beam widths, of any antenna type.

Fig of Parabolic Reflector Antenna

Parabolic antennas are based on the geometrical property of the paraboloid that the paths FP1Q1, FP2Q2, FP3Q3 are all the same length

Applications

1) Point-to-point communications

2) In applications such as microwave relay links that carry telephone and television signals between nearby cities, WAN/LAN links for data communications, satellite communications and spacecraft communication antennas.

3) They are also used in radio telescopes

Slot Antenna Slot antennas are used typically at frequencies between 300

MHz and 24 GHz. The slot antenna is popular because they can be cut out of whatever surface they are to be mounted on, and have radiation pattern that are roughly Omni directional (similar to a linear wire antenna, as we'll see).

Fig of Slot antenna :-

The polarization of the slot antenna is linear. The slot size, shape and what is behind it (the cavity) offer design variables that can be used to tune performance.

Consider an infinite conducting sheet, with a rectangular slot cut out of dimensions a and b, as shown in Figure 1. If we can excite some reasonable fields in the slot (often called the aperture), we have a slot antenna.

Lens Antenna

Lens antenna can be used in the high frequency end of microwave. In fact the frequency range of lens antenna starts at 1 GHz but its greatest use is beyond 3 GHz. At lower frequencies lens antennas become bulky & heavy.

There are several type of lens antenna:- Dielectric lens or H-plane metal plate lens E-plane metal plate lens

Figure of Lens antenna

Applications of lens antenna

As lens antenna is a microwave antenna, it is most widely used at a microwave frequency above 3000 mhz.

For larger bandwidth requirements, unstopped dielectric lens is used because its shape is not dependent on wavelength. For narrow bandwidth applications dielectric lens antennas are used.

THANK YOU