Study of High-Temperature Superconductor Diplexers for Satellite Communications

The high-temperature superconductor （HTSC） resonator and diplexer are simulated by full-wave tools. A newly developed miniature HTSC diplexer is designed and fabricated on double sided YBa2Cu3O7 （YBCO） film （YBCO/LaAlO3/YBCO）, the thickness of which is 400 nm for YBCO and 0.5 mm for the LaAlO3. The measured results show a good agreement with the simulation. The volume and mass of the diplexers are greatly reduced by miniaturized configuration.

Interference and Spectral Efficiency Analysis in Two-hop Cellular Network with Fixed Relays in FDD Mode

This paper presented a scheme of two-hop cellular network with fixed relay nodes (FRN). Based on this scheme, co-channel interference and signal interference ratio(SIR) received by base station(BS) and FRN were analyzed. Both the theoretical analysis and simulation results show that the SIR can be improved significantly when relays are employed in the network. The higher spectral efficiency can be obtained due to the improved two-hop link quality through the use of adaptive modulation and coding (AMC). The antenna height of FRN and the cell radius of BS and that of FRN influence SIR received by BS and FRN and the system spectral efficiency greatly. The proper antenna height of FRN and cell radius of BS and that of FRN were also given to get the highest spectral efficiency.

Coupled Resonator Diplexer without External Junctions

A coupled resonator diplexer has been designed, fabricated, and tested. The design is based on synthesis of coupling matrix of a 3-port coupled resonator circuit using optimization. Unlike conventional diplexers, the presented diplexer configuration does not include any separate junctions for distribution of energy. The diplexer has been implemented at X-band with waveguide cavity resonators, and its measured response is in good agreement with the simulated response.

Design and Fabrication of a Low-Loss Microstrip Lowpass-Bandpass Diplexer for WiMAX Applications

This work presents a compact lowpass-bandpass microstrip diplexer with a novel configuration.It consists of a lowpass filter integrated with a bandpass filter via a simple compact junction.The proposed bandpass filter consists of four rectangular patch cells and some thin strips.The step impedance structures,with a radial cell,are applied to achieve a lowpass frequency response.The lowpass channel of the introduced diplexer has 2.64 GHz cut-off frequency,whereas,the bandpass channel center frequency is 3.73 GHz for WiMAX applications and covers the frequencies3.31 GHz to 4 GHz.In addition to having novel structures,both filters have other advantages in terms of high return loss,low insertion loss and high selectivity.The presented microstrip diplexer has the compact size of 29 mm×13.8 mm×0.762 mm,calculated at 2.64 GHz.The obtained insertion losses are 0.20 dB(for the first channel)and 0.25 dB(for the second channel),which make the proposed diplexer suitable for energy harvesting.The stopband properties of both bandpass and lowpass filters are improved by creating several transmission zeros.The comparison results show that the lowest insertion losses,the minimum gap between channels,good return losses,and good isolation are obtained.