Analysis and design of microwave zonal plate antenna for satellite tv receiption system

The zonal plate antenna is a new design of flat aperture antenna based on Huygen’s principle and Fresnel diffraction theory; therefore it’s called Fresnel zone antenna. This work attempts to give full analysis of this type of antenna and make software and hardware implementation of this project. The analysis in this thesis includes two types of Fresnel antenna (the Soret type and the Wood type). These two types of antenna are different in shape, design procedure and the manufacturing techniques. They are also different in the characteristics of the antenna like radiation pattern, directivity and aperture efficiency for the same design parameters i.e. operating frequency (f), number of zones (N) and focal length (F). Published local work on the detailed analysis of Fresnel antennas is scarce. The present work starts from Maxwell's equations and uses several principles and theories to arrive at the equations which calculate the radiation pattern for both types .It also gives the derivation of the equations which calculate the radii of Fresnel zones (rings), directivity, aperture efficiency and other properties of this antenna. The MATHCAD program of zonal plate antenna has been implemented to calculate and draw the radiation field pattern according to the equations which have been derived in the theoretical analysis. This work also provides a different approach (Henry Wallace method) for calculating the radii and field pattern of zonal plate antenna and also provides the corresponding software program. A comparison has been made between these approaches to explain the differences between their characteristics. Hardware implementation of a zonal plate antenna has been made with the following design parameters: operating frequency f=11.1GHz, number of zones N=6 (even zones), focal length F=2m and aperture diameter D=1.14m. Several experiments have been done to test this design in order to measure the radiation field of this antenna and to use it as a satellite TV reception system. One of these experiments has been done by using the kit no. 741 to measure the radiation field; this kit consisted mainly of three parts (1) Gunn Oscillator which is used to generate microwaves.(2) Large Horn Antenna which is used as feeding radiator for dish antenna.(3) E-Field Probe which is used for the point-by-point measurement of the microwave fields.The second experiment has been done using the Fresnel zone antenna as satellite TV reception system. The first part of this experiment is to use the antenna as reflecting antenna (Reflection Mode) by putting a reflecting plate behind it and place the LNB at a distance 2 m from the center; the received signal in the reflection mode is not noticeable However, in the second part of this experiment the antenna was placed between the satellite and the LNB (Diffraction Mode). A signal from the NILESAT satellite had been received and it’s strength was about (17-25)%. The reasons for not very good results are:
1- The antenna might be not 100% directed to the NILESAT.
2- The LNB might not be exactly in the focal point.
3- The dimensions of the antenna (i.e. the radii of the zones) are little different
from that calculated theoretically due to manufacturing reasons.