Reduced coupling levels between a radio altimeter and spiral antenna module on an aircraft at 4.3 GHz

Modem aircraft typically have numerous antenna performing different tasks, sometimes in the same frequency range. It is therefore desirable to reduce their effect on one another as much as possible. One such example is that of a RADALT and SAM mounted on the tail section of an aircraft. The radio altimeter (RADALT) and spiral antenna module (SAM) are numerically modeled using SuperNEC to determine and reduce their coupling levels. Simulations with a shielding plate configuration showed that the difference in coupling levels yielded 9.1 dB reduction in the horizontal component and 5 dB reduction in the vertical component of the SAM. Simulations with parasitic wires showed that the difference in coupling levels yielded 6.4 dB reduction in the horizontal component and 6.9 dB reduction in the vertical component of the SAM.