Design methodology for dual-band hybrid antennas with off-resonance loading

The presented work proposes a generalised design methodology for dual-band hybrid antennas. The methodology is applied to a dual-band hybrid antenna system operating in two modes; one allows the antenna to radiate at a lower frequency band, whereas the other operates the antenna at a higher frequency band. The lower band radiating element is also responsible for exciting the higher band radiating element. Since the two radiating modes depend on each other, the antenna system is characterised in detail to achieve efficient impedance matching for both the modes. An efficient model is proposed that models the true behaviour of the system. A hybrid dual-band antenna has been modelled, designed and fabricated. Test results exhibit desired radiation behaviour as well as good impedance match for both the bands. The proposed design methodology allows the design of antenna for each radiating mode quasi-independently. This design methodology can be applied to any similar type of antenna which exploits multiple radiating elements where one is loaded by another.