A Miniaturized Multi-functional Antenna with UHF and CP Performance for Communication and Navigation System

In this paper, a multi-functional antenna system for both communications and navigation is presented. The proposed antenna combined a sleeve monopole antenna for vertical polarization (VP) and a patch antenna for right-hand circular polarization (RHCP). The VP sleeve monopole element is designed for UHF band, and a spiral slot is etched around the side wall to reduce the height of the antenna. The RHCP element is an annular-ring patch antenna designed for Beidou B3 frequency band. The CP performance is realized by a small surface-mounted 0 degrees-90 degrees hybrid chip integrated in the feed network. The UHF antenna is co-located concentrically on the top of the patch antenna with a relative height of 0.03 lambda. An insulating gasket is put between the UHF and the B3 antenna for the compact structure. The UHF antenna achieves a bandwidth of 2% from 390 to 398 MHz and gain up to 2.7 dBi in the frequency band. The patch antenna works in a broad bandwidth covering the whole B3 band for RHCP. An port isolation of 25 dB is achieved in B3 band. Details of the antenna design as well as the simulated results are presented and discussed.