Answer:
i) To find the effective aperture and aperture efficiency of the pyramidal horn antenna, we need to use the given equation:
abD = 10λ
where a is the aperture width and b is the aperture height. λ is the wavelength.
We can rearrange the equation to solve for D:
D = 10λ / (ab)
The effective aperture, Aeff, is given by:
Aeff = ab / D
The aperture efficiency, η, is given by:
η = Aeff / A
where A is the physical aperture area.
ii) If the power density around the antenna is 1 W/m², we can calculate the received power using the formula:
Pr = Aeff * power density
iii) The effect of aperture size on received power can be analyzed by observing the relationship between the aperture size (a and b) and the effective aperture (Aeff). Generally, a more considerable aperture size results in a larger effective aperture, which in turn leads to higher received power. This is because a larger aperture captures more energy from the incoming wavefront, resulting in increased power transfer to the antenna.
b) The four major features of the antenna far-field are:
Radiation Pattern: The far field of an antenna exhibits a specific radiation pattern, which describes the spatial distribution of radiated power in different directions.
Beamwidth: The beamwidth of an antenna is the angular width of the main lobe in the radiation pattern. It determines the angular range the antenna radiates or receives power effectively.
Directivity: The directivity of an antenna is a measure of its ability to concentrate radiated power in a particular direction. It quantifies the antenna's ability to focus energy in a specific order compared to an isotropic radiator.
Polarization: The far field of an antenna also exhibits a specific polarization characteristic. It can be linearly or circularly polarized, depending on the antenna design and orientation of the electric field vector.