Co-aperture arrangement of dual antennas for orientation and telemetry in a conformal cavity

The feasibility of making two antennas work within a shared aperture conformal to a platform like an aircraft or a missile is investigated. The shared aperture is enclosed by a deep cavity, which is covered by a columniform dielectric radome. A modified quadrifilar helix antenna (QHA) with extended volute arms and a vertical monopole with a ring shaped ground are arranged in this co-aperture for global position system (GPS) orientation and telemetry, respectively. The effects of the cavity on these two antennas and the mutual coupling between these two antennas are studied through large numbers of experiments. The results show that the QHA has a strong influence on the monopole; however, these two antennas of the overall arrangement can perform simultaneously well within the aperture. The QHA has a right hand circular polarization (RHCP) and a broad beam normal to the radome topside, meanwhile the monopole can be used to produce a main lobe in the grazing direction above the aperture in some certain cases of the vertical location of the QHA in the cavity.