 Myself Piyusha Shedgar, Assistant Professor Electronics and Telecommunication Engineering Valchand Institute of Technology, Solapur. In today's session, we will continue the slot antenna part 2. These are the learning outcomes for today's session. At the end of this session, students will be able to explain the impedance of slot antenna. They will be able to list the applications of slot antenna. In today's session, we will discuss the impedance, advantages, disadvantages and applications of the slot antenna. So, before going to start actually the impedance consideration for the slot antenna, you can pause video here for a second and recall that what is slot antenna? Yes, a slot antenna is a radiator made by cutting a one half wavelength slot in a conducting sheet of metal or into the side or top of a waveguide. So, this is how the slot antenna can be constructed. So, here it is the metal sheet is considered with higher conductivity. So, the higher conductivity means that you can consider the conductivity for this is the infinite. In infinite conducting sheet, a rectangular slot is cut at the center of this metal sheet with the dimensions A and B, then it forms the slot antenna. If we can excite some reasonable fields in the slot, we have this type of the antenna is nothing but the slot antenna. It is often called as the aperture antenna. Slot antenna follows the Babinette's principle. So, what is the Babinette's principle? The Babinette's principle states that the sum of the field at a point behind a plane having screen and the field at the same point when a complementary screen is substituted is equal to the field at that same point when no screen is present. So, the Babinette's principle is used to reduce the problems in the slot antenna. It relates the radiated fields and the impedance of an this aperture or the slot antenna to that of the field of its DL antenna. So, DL antenna here you can consider as the dipole antenna. So, generally the complement of the dipole antenna is nothing but the slot antenna. So, whatever is the construction of the slot antenna and the dipole antenna, these two are complement to each other. So, it is also called as a DL antenna. So, the dual antenna of a slot antenna which having the conductive material and air were interchanged that is the slot antenna become a metal slab in a free space. So, here the in the figure you can observe that this is the metal sheet and a slot rectangular slot is cut at the center for the slot antenna where in the case of the dual antenna this slot is provided with the metal sheet that is the complement of this part. So, suppose the length for this slot is nothing but the lambda by 2 that lambda by 2 length is considered with the metal sheet whereas, around of this there is nothing. So, this means that these two are complement to each other. So, when this complement is of the antennas are considered these are called as the dual antennas. So, what is the impedance of a slot antenna? So, the impedance of a slot antenna plays a very important role while deciding the voltage source or the electric field distribution within the slot. So, whenever the voltage source is applied across the short end of the slot antenna, it induces an electric field distribution within this slot. In that case the currents which travel around the slot perimeter these both are contributed to the radiation. In dual antenna that is you can consider the dual antenna as a dipole antenna. In dual antenna the voltage source is applied at the center of the dipole so that the voltage source is rotated. Now, suppose the Babinitz principle relates these two antennas slot antenna and the dipole antenna. So, suppose the Zs is considered as the impedance of the slot antenna which is complement to the dipole antenna impedance that is Zd. So, it is also called as the complementary dipole antenna impedance. So, these two are related with the equation Zd dot that is multiplication of Zd and Zs is equal to eta square by 4. So, generally the eta is nothing but having the value equal to 120 pi because it is considered for the free space. Where in this equation Zs denotes impedance of the slot antenna and Zd denotes the impedance of its dual antenna that is dipole antenna and eta denotes the intrinsic impedance of free space. So, it is given by the value equal to 120 pi. So, whenever you know the dipole antenna impedance so, generally the dipole antenna impedance having the value equal to 73 ohm with the real part. So, whenever you are putting the dipole impedance equal to 73 ohm and eta equal to that is intrinsic impedance equal to 120 pi then you are getting the nearly value for the impedance of the slot antenna equal to near to 485 ohm. So, it having the 485 ohm maximum impedance as compared to the impedance of the dipole antenna it having the 73 ohm value. So, here it reduces the attenuation. So, now the field components of the slot antenna so, the babinets or Bucher's principle Bucher's principle is somewhat the extension part of the babinets principle is that the fields of the dual antenna are almost the same as that of the slot antenna. So, that means, when the fields are interchanged field components are interchanged in case of the duals. So, the field of the dipole antenna and the field of the slot antenna can be relate to each other with the given equation below. So, here it is given by this equation so, whenever the electric field component is considered in case of the slot antenna then the dipole antenna having the consideration with the magnetic field component. So, here the theta s, s is nothing but the slot antenna the electric field component of the slot antenna is equal to the complement of the magnetic field component that is the slot antenna is having the electric field component which is equal to the dipole antenna magnetic component. So, the magnetic component for the slot antenna it is given by minus electric field of complement component upon the eta square thus these two are relates to each other these are the field components of the slot antennas. Now, the field components of the slot antennas knows the fields from one antenna then we can calculate the other field component from the other antenna. So, it is very easy to visualize the fields from the dipole antenna. So, the fields and the impedance from a slot antenna can become the intuitive if babinets principle is understood, but the polarization of the two antennas are reversed. Advantages of the slot antennas so, it can be fabricated and concealed within the metallic objects it can provide covered communication with small transmitter along with some of the disadvantages it having the higher cross polarization levels it having a lower radiation efficiency and some of the applications of the slot antennas are it apply usually for radar navigational purposes it is used as an array fed by a waveguide. So, the slot antenna having the number of applications because of this babinets principle is used. So, by using this babinets principle you can relate this slot antenna to the dipole antenna. So, which having the highest mechanical stability and the greater communication application. So, these are the references for today's session. Thank you.