Low-Profile Multiband Ferrite Antenna for Telematics Applications

Abstract

Miniature low-profile multiband ferrite antennas were designed with various BaCo1.4Zn0.6Fe16O27 hexaferrite loading configurations and fabricated for telematics applications. Experimental permeability ( $\mu ^\prime $ ) of 2.0, permittivity ( $\varepsilon ^\prime $ ) of 7.3, magnetic loss tangent (tan $\delta _{\mu }$ ) of 0.035, and dielectric loss tangent (tan $\delta _{\varepsilon }$ ) of 0.005 at 1 GHz were used for antenna performance simulations. It is observed that a hollow rectangular ferrite substrate loading shows simulated maximum ripple levels ( $\Delta = E_{\theta \_{}\max }-E_{\theta \_{}\min }$ ) of 2.2, 3.0, and 1.9 dB at the first ( $f_{1}$ ), second ( $f_{2}$ ), and third ( $f_{3}$ ) resonant frequencies, respectively, implying wider coverage than other loading configurations. Miniaturization factor is greater than that of air-core antenna, and the impedance matching and bandwidth are improved with the ferrite loading. Higher gain of the ferrite-loaded antenna than the air-core antenna was observed at $f_{2}$ and $f_{3}$ , while the gain at $f_{1}$ remains almost the same. Moreover, the vertical component $E_{\theta }$ is greater than the horizontal component $E_{\phi }$ , showing the vertically polarized operation of the antenna. Based on the measured and simulated results, it is concluded that the BaCo1.4Zn0.6Fe16O27 substrate loading allows antenna miniaturization with enhanced antenna performance.