Investigation for impact behavior of composite surface antenna
We study the impact characteristic and the performance of composite surface antenna (CSA). The antenna, which operates in GPS band (1.575 GHz) and DMB band (2.635 GHz), was embedded in composite sandwich structure consisting of glass/epoxy laminate, carbon/epoxy laminate, adhesive films and nomex honeycomb. When 20 J of impact energy was applied to arbitrary points on the antenna, the maximum contact force was 4 kN and the antenna proved resistant to impact. The gain of antennas after impact testing was about 6 dBi in GPS band and 4.5 dBi in DBS band.
Combined multi-band antenna for GPS and WLAN applications
Linear and circular polarisations are ofen used respectively for terrestrial and spatial communications. In this paper, we propose a new complex multi-band antenna working simultaneously in linear and circular polarisations for WLAN, GPS1 and GPS2 standards. This antenna is a combination of stacked patches, printed on ceramic substrates, with a metallic monopolar type structure within a metallic cavity placed in the center of the previous patches.
Submicron polymer structures with X-ray lithography and hot embossing
This article describes the process chain for replication of submicron structures with varying aspect ratios (AR) up to 6 in polymethylmethacrylate (PMMA) by hot embossing to show the capability of the entire LIGA process to fabricate structures with these dimensions. Therefore a 4.7 μm thick layer of MicroChem 950k PMMA A11 resist was spin-coated on a 2.3 μm Ti/TiOx membrane. It was patterned with X-ray lithography at the electron storage ring ANKA (2.5 GeV and λc ≈ 0.4 nm) at a dose of 4 kJ/cm3 using a Si3N4 membrane mask with 2 μm thick gold-absorbers. The samples were developed in GG/BDG and resulted in AR of 6–14. Subsequent nickel plating at 52°C resulted in a 200 μm thick nickel tool of 100 mm diameter, which was used to replicate slit-nozzles and columns in PMMA. Closely packed submicron cavities with AR 6 in the nickel shim were filled to 60% during hot embossing.