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Proposed is an ultra-low-profile loop antenna backed by an electromagnetic bandgap (EBG) surface reflector, where the EBG surface can effectively exhibit the property of a perfect magnetic conductor (PMC) inside a deliberately designed bandwidth. It is shown that, assisted by the effective PMC bandwidth, while the proposed antenna is with a 0.07-λ spacing between the loops and the EBG reflector, its axial ratio (AR) and voltage standing wave ratio (VSWR) performances are significantly improved. Experimental measurements show that the prototype antenna has a 3 dB AR bandwidth of 17% with an input VSWR less than 1.6. The proposed approach can find a wide range of low-profile circularly polarised (CP) antenna applications.

A deterministic beam-forming approach aiming at synthesising differently shaped beams for a partial, spherical-surfaced conformal aperture is presented. It is mathematically shown that current distribution on such an aperture can be expanded into a Fourier series, and its far-field radiation pattern can be further expressed in a concise closed form. If the aperture distribution satisfies a weighted zeroth-order or first-order spherical Bessel function, one can easily achieve various shaped beams such as pencil, flat-topped and bimodal beams by simply tuning a single weighting coefficient of the Bessel function. The proposed approach is deterministic and intuitive, making it possible to achieve fast, real-time beam-forming for spherical conformal arrays.

The ability of selected strains of fluorescent Pseudomonas spp. to cause induced systemic resistance (ISR) in Eucalyptus urophylla against bacterial wilt caused by Ralstonia solanacearum was investigated. Four of the five strains used can produce salicylic acid (SA) in vitro and, therefore, chemical SA, that is known to induce resistance in many plant species, was used as a reference treatment. Whereas a soil drench with SA did induce systemic resistance in E. urophylla, infiltration of SA into leaves did not. None of the fluorescent Pseudomonas spp. strains caused ISR against bacterial wilt when applied to the soil, but two strains, P. putida WCS358r and P. fluorescens WCS374r triggered ISR when infiltrated into two lower leaves 3-7 days before challenge inoculation. A mutant of strain WCS358r defective in the biosynthesis of the fluorescent siderophore pseudobactin, did not cause ISR, while the purified siderophore of WCS358r did, suggesting that pseudobactin358 is the ISR determinant of WCS358. A siderophore-minus mutant of WCS374r induced the same level of disease resistance as its parental strain, but the purified siderophore induced resistance as well, indicating that both the siderophore and another, unknown, inducing determinant(s) of WCS374r can trigger ISR in Eucalyptus. A possible role of WCS374r-produced SA remains uncertain. Transformation of a siderophore-minus mutant of WCS358 with the SA biosynthetic gene cluster from WCS374 did not enable this transformant to cause ISR in E. urophylla.