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Abstract-This paper proposes the configuration of a dualpolarized wide-band patch antenna system suitable for indoor mobile communication applications. This configuration consists of two patch antennas, which have different feed structures from classical patch antenna configuration. These antennas, which are separated by a thin absorber to have a good isolation, are fed independently to obtain dual polarization. The antenna structure is designed, simulated, manufactured and measured. The operation bandwidth spans 1900-2700 MHz covering Bluetooth, Wireless Local Area Networks (WLAN) and Universal Mobile Telecommunications System (UMTS) bands. The simulations show good agreement with the measurement results that the antennas have return losses higher than 15 dB, and the coupling between two antennas is below −20 dB within the operation band.

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In this study, the realization of a Ku‐band feed system for reflector antenna in satellite communication systems is presented using 3D printing and conductive paint methods. The system includes a corrugated conical horn antenna designed to operate at 10.5 to 18.5 GHz and an H‐plane waveguide diplexer to operate at 10.7 to 12.75 GHz and 17.3 to 18.4 GHz in receive (RX) and transmit (TX) bands, respectively. In the manufacturing of the structures, fused deposition modeling (FDM) technology and polylactic acid material are processed for 3D printing, where nickel and silver conductive‐based paints are used for coating purpose. The measurement results of the feed system are found to be in good agreement with simulations that the combined (nickel‐coated antenna and silver‐coated diplexer) structure has return loss of more than 10 dB and high gain performance of 12 to 17 dBi within the RX and TX bands of 10.7 to 12.75 GHz and 17.4 to 18.8 GHz, respectively; while rejection (isolation) level between TX and RX ports is higher than 60 dB. The complex structure containing several detailed shapes inside shows that this low‐cost production technique as compared to high‐cost CNC‐based metallic production technology can be used for the prototype structures or proof‐of‐concept type studies of Ku‐band systems.

A surface treatment was applied to carbon black to improve the electrical and microwave properties of poly(ethylene terephthalate) (PET)-based composites. Three different formamide solutions with 1, 2, and 3 wt % concentrations were prepared to modify the surface chemistry of carbon black. Microwave properties such as the absorption loss, return loss, insertion loss, and dielectric constant were measured in the frequency range of 8-12 GHz (X-band range). Composites containing formamide-treated carbon black exhibited enhancements in the electrical conductivity, electromagnetic interference (EMI) shielding effectiveness, and dielectric constant values when compared to composites with untreated carbon black. In addition, increases in the formamide solution concentration and carbon black content of composites resulted in an increase in the electrical conductivity, EMI shielding effectiveness, and dielectric constant values. The percolation threshold concentration of PET composites shifted from a 3 to 1.5 wt % carbon black composition with the surface treatment. The best EMI shielding effectiveness was around 27 dB, which was obtained with the composite containing 8 wt % carbon black treated with a 3 wt % formamide solution. Moreover, this composition gave the lowest electrical resistivity and the highest dielectric constant among the produced composites.