Search

A dual-band omnidirectional circularly polarized (CP) antenna using composite right/left-handed (CRLH) transmission line (TL) with miniaturized size is presented. The antenna consists of a circular radiation patch and a circular ground connected by three copper shorting vias, on which three rectangular slits are etched. Two sets of opposite branches are arranged in sequence around the radiation patch and ground to widen the impedance bandwidth (BW). The zeroth-order resonance (ZOR) structure by CRLH-TL and meandering technology allow miniaturization of the antenna, and rectangular slits realize wide low axial-ratio (AR) performance in the azimuth plane. The dual-band antenna is fabricated and measured. The overall size of the antenna prototype is only 0.208λL × 0.208λL × 0.026λL, where λL is the free-space wavelength at the center working frequency of the low band. The BW in the lower band has a range of 2.39 GHz to 2.42 GHz, equivalent to 1.25%, and that of the upper band has a range of 5.6 GHz to 6.0 GHz, equivalent to 6.90%. The AR bandwidth (ARBW) has ranges of 1.9 GHz to 2.6 GHz at 2.4 GHz, approximately 29.2%, and 4.6 GHz to 7.3 GHz at 5.8 GHz, equivalent to 46.6%. The overlap BW covers the two frequencies of unmanned aerial vehicle (UAV) image transmission, 2.4 GHz and 5.8 GHz in China.

Microstrip antenna is often used in remote sensing imaging and so on. For biomolecules detection, microstrip sensor is expected to achieve higher sensitivity and lower noise. A novel microstrip biosensor is proposed in this paper，which is based on printed nanowires array for ultralow concentration protein detection. The incorporation of nanowires array into microstrip sensor can greatly improve the electric field strength. The prepared nanowires not only have uniform arrangement, good coherence and large area of repeatability, but also have direct biological functional groups, which can stably capture biological molecules. The experimental results show that very low concentration of biological molecules applied on the sensor can cause changes in microwave signals, thus achieving ultra-sensitive detection results.