An equivalent LC model is developed to emulate the filter performanceto accelerate the design procedure. The source-load coupling renders this filter a cross-coupling effect which creates two transmission zeros by the passband edges for the signal selectivity enhancement.

A novel balanced BPF using the folded half-mode substrate integrated waveguide has a central frequency of 4.65 GHz with 0.55 GHz BWin-band insertion loss of 2.2 dB. The size of an FHMSIW is about 1/4 of the substrate integrated waveguide (SIW). The common-mode rejection levels are greater than 40 dB over a wide frequency range.

A phosphate-sensing chip was constructed by a copper phosphate-deposited electrode. The modification of ionic liquidplasticizer can improve the selectivity of phosphate anionsreduce the interference of sulfate, nitratechloride anions. The sensing chip equipped with a portable electrochemical device can directly detect the phosphate concentration of solution extracted from soil samples in ten minutes by using amperometry. The sensing chip promises the feasibility of detecting the phosphate concentration without expensive instrumentlabor-intensively chemical colorimetry.