What term refers to the area of an antenna that intercepts EM radiation?

What term refers to the area of an antenna that intercepts EM radiation?

• A. Polarization
• B. Reciprocity
• C. Feedhorn
• D. Aperture

Answer: (D)

The area that intercepts electromagnetic radiation is called the aperture. In antenna theory, the aperture represents the region through which energy effectively enters or leaves the antenna. The power the antenna can capture is tied to its effective aperture, A_e, which equals the physical opening area times an efficiency factor that accounts for losses and illumination. For a dish, the illuminated dish area is the aperture; for a horn, the mouth of the horn is the aperture. A larger aperture (or higher aperture efficiency) means more power can be intercepted for a given wave flux, and it also influences the antenna’s directivity. Polarization is about the orientation of the electric field of the wave, not the area that intercepts it. Reciprocity is the principle that the transmission and reception behavior are interchangeable in a linear passive system. A feedhorn is a component used to feed the antenna, not the area that intercepts radiation.

The area that intercepts electromagnetic radiation is called the aperture. In antenna theory, the aperture represents the region through which energy effectively enters or leaves the antenna. The power the antenna can capture is tied to its effective aperture, A_e, which equals the physical opening area times an efficiency factor that accounts for losses and illumination. For a dish, the illuminated dish area is the aperture; for a horn, the mouth of the horn is the aperture. A larger aperture (or higher aperture efficiency) means more power can be intercepted for a given wave flux, and it also influences the antenna’s directivity.

Polarization is about the orientation of the electric field of the wave, not the area that intercepts it. Reciprocity is the principle that the transmission and reception behavior are interchangeable in a linear passive system. A feedhorn is a component used to feed the antenna, not the area that intercepts radiation.