Antenna & Wave Propagation (Tution Ch-5) PDF

# KHUSHI ## Unit: 5 Antenna & wave propagation ### Define: Electromagnetic Spectrum " It is a portion which consist of, Infrared radiation, Visible light or Ultraviolet radiation. ### Types of radiation | Radiation | Frequency | |---|---| | Gamma | 10^20 - 10^24 Hz | | X-ray | 10^5 - 10^20 Hz | | U...

# KHUSHI ## Unit: 5 Antenna & wave propagation ### Define: Electromagnetic Spectrum " It is a portion which consist of, Infrared radiation, Visible light or Ultraviolet radiation. ### Types of radiation | Radiation | Frequency | |---|---| | Gamma | 10^20 - 10^24 Hz | | X-ray | 10^5 - 10^20 Hz | | Ultra | 10^5 - 10^9 Hz | | Visible | 4x10^14 - 7.5 x 10^14 Hz | | Infrared | 10^13 - 10^14 Hz | | Microwaves | 3x10^9 - 10^13 Hz | | Radio | 3x10^11 Hz | ### Application * It is used in mobile comm. * It is used in radio broadcasting * " " Wi-fi * " " Cooking * " " Medical imaging * " " Treating cancer ## Define: Antenna "It is metallic devices such as rod or wire for radiating or receiving radio waves Is called Antenna." ### Radiation pattern at Antenna: " It is the graphical representation of the radiation property of the Antenna as a function of space." ### Basic lobes * Side lobes * Radiation intensity * V - field * E field * H-field. ### Isotopic Antenna: it is perfect radiation pattern that radiate electromagnetic energy equal in all direction. ### Polarization at Antenna: The direction at EM wave prodce energy radiate away from it. ### Directivity: Directivity of an Antenna is defined as the ratio of the radiation intensity in given direction from the Antenna to the radiation intensity averaged over all direction. ### Gain: It is ability of Antenna to focus the radiation to a particular direction. ### Dipole Antenna: * Max radiation * Axis of Antenna * V → A dipole Antenna also known as doublet or dipole aerial. → It is Radio frequency Antenna. → It consist of two conductive elements such as rods or wire. → Dipole antenna are the simplest and most widely used type of antenna. → "Dipole" means two poles. ### The length of metals while is half the wavelength(λ). ### Parabolic reflector Antenna * Reflected rays * Feed * Hyperbolic sub-reflector * Parabolic main reflector → A parabolic reflector with an Antenna feed at the focal point will radiate energy from the reflector with parallel rays. → It is also known as dish antenna. → It is used in VHF where high gain or directivity is needed. → Size of Antenna is large. → It require careful installation ### Micro strip antenna * Patch current * It is also known as patch antenna * It is modern invention. * It is integrated antenna for comm. system with the help of PCB & semiconductor cheap. * V * Metal patch → It produce max radiation in broadside → It is widely used in gigahertz range → Advantages - low cost, comfort shape, light weight, less efficiency, poor radiation. → It is also known as planar inverted F antenna. → It is also known as PIFA- monopole antenna. → It is low profile, compact size, suitable in small devices like mobile. → It is used in wireless comm. system. → It is used for single or multi. ### Ground Antenna * It is Gaory foam * It is used for intelligent algorithm to calculate convert to small of Antenna. * It is also known as metallic plate * It is used for transmitting & receiving non-ionizing radio fields (radio waves) * Need of antenna - to experience with better coverage coefficient with having high density is called IR. * It is used in signal processing. * It is used in electronic beam forming. ### Advantages * Because expensive. * Installation requires to opposite. ## Comparision of Ground wave, Space wave & Sky wave | Wave | Freq range | Freq range | Freq range | |---|---|---|---| | Ground wave | 30 KHZ - 3 MHZ | 310 - 30 MHZ | Above 30 MHZ | | | It is used for MW | It is used for SW | It is used for TV & FM broadcasting | | | Vertically polarized | Vertically polarized | Horizontally polarized | | | X mission limited by skip distance | X mission limited by radio horizon | X mission limited by surface | | | It travel in straight line from TX & ex | It travel in straight line from TX & ex | It reflect from Ionosphere | | | Service range is few hundred KM | Service range is few thousand KM | Service range is more than 100 km | | | Power loss due to absorption by ground | Power loss due to lisorption at energy | Power loss due to power absorption by tall & massive object. | | | Proplem of fading is not very serve | Fading is serve | Shadow zone effect to fading | | | Used in MW | Used in SW | It is used for satellite communication | | | Tall Antenna require | Power loss occur | Distance limited due to gain & tog |