Band 65, Heft 1-2

In this paper, characteristics of a compact filter based on multilayered (ML) composite right/left-handed (CRLH) transmission line (TL) are thoroughly investigated. Rules for designing compact filters with high performances are obtained. By adjusting different structure parameters such as the width and length of the rectangular line, the distance between two U-shaped parallel plates, the center frequency can be increased and the bandwidth can be expanded. Meanwhile, harmonic resonance is suppressed and performances are improved effectively. A compact filter, which uses the multilayered low-temperature co-fired ceramic (LTCC) technology, is fabricated to proof these results. With physically compact dimensions 5.1 mm × 3.8 mm × 2.6 mm, this filter not only has high center frequency (about 10 GHz), but demonstrates good performances including 1.45 dB in-band loss, –25 dB transmission coefficients at 8 GHz, and 1 GHz bandwidth. Both simulated and measured results are shown to support the proposed rules.

A new rectangular cavity loaded with metamaterial structure is proposed. Its properties of resonant frequency and the distributing of near field are analyzed. Simulated results show that it not only can resonate at subwavelength but that it has also a good radiation feature used as antenna. The speciality that the resonant frequency will change with different value of negative permeability enlightens us to design a frequency continuously reconfigurable antenna for cognitive radio instead of conventional methods used MEMS to reconfigure the shape of radiator. SRRs integer with capacity and varactor diode are used to realize changing mu-negative material by controlling the voltage. According to the near field magnetic orientation, a proper alignment is chosen. At last, a simple antenna is designed. Dimensions of this antenna are very small compared to resonant wavelength (about 10%) and its frequency can be reconfigured continuously in a broadband from 342MHz to 463 MHz. Radiation patterns of the antenna are stable and the maximum gain is above 0 dBi in all operation bands. This may indeed open interesting venues for the design of electric small antennas with continuous frequency reconfigurable performance.

We present results of microwave measurements of four different nematic mixtures which were prepared out of a tolane matrix by adding some specific quaterphenyl containing LC-compounds. Those high birefringent matrices lead to the improved performance within the microwave wave range. The measurements were done by using the cavity perturbation method at 38 GHz in the temperature interval of –5 °C and 135 °C.

A fast-locking frequency synthesizer is designed for single-chip UHF RFID Reader. Different from the traditional UHF RFID frequency synthesizer, the technology of multi-modulus divider (MMD) is adopted here, which greatly reduces the design complexity. More importantly, two inverters and one toggle circuit are added to the output of the multi-modulus divider to improve the output load driving capability and the operation speed of the phase frequency detector (PFD), so as to reduce the locking time of the frequency synthesizer. Finally an improved divider by 2 is used at the output stage of the frequency, and the performance of the output waveform is improved. The simulation is made by Cadence in chartered 0.18 μ m CMOS process. The simulation result shows that the output waveform is very good and the locking time is less than 10 μ s. The phase noise of the output signal are approximately –104.8 dBc/Hz at 200 KHz and –124.6 dBc/Hz at 1MHz offset from 900MHz operating frequency, which is suitable for UHF RFID Reader. The frequency synthesizer dissipates 28.2mW with a 1.8V supply voltage.

In this paper a high resolution dual-loop 17.7–19.7 GHz frequency synthesizer is presented which is compatible with ITU-R (F.595-6) standards. The investigations of phase noise and spur frequency contents are discussed in detail. The simulated and measured phase noise and spur frequency contents are similar to one another. Phase noise of –81 dBc/Hz in 17.7 GHz at 10 KHz offset frequency is measured by (HP8560) series Spectrum analyzer and it matches with predicted measurements.

In this paper, automatic modulation recognition of mixed multiple source signals is discussed. At first, the algorithm of equivariant adaptive source separation (EASI) is employed to separate signals from their mixed waveforms. Four features of five modulated signals are extracted and then two classifiers, decision tree and neutral network are used to complete modulation classification. The effects of symbol shaping on features extraction and validation of source separation are also investigated. Simulations show that the average probability of correct recognition of the classifiers is very depended on the performance of source separation. When SNR (Signal to Noise Ratio) is larger than 15 dB and the number of mixed source signals is less than 4, the average probability of correct recognition is above 0.6 for decision tree classifier and 0.63 for neutral network classifier. Simulations and discussions about automatic modulation recognition for source signals surfed Rayleigh flat fading are also presented.

This paper presents a current-mode common-mode feedback (CMFB) circuit with rail-to-rail operation. The CMFB is a stand-alone circuit, which can be connected to any low voltage transconductor without changing or upsetting the existing circuit. The proposed CMFB employs current mirrors, operating as common-mode detector and current amplifier to enhance the loop gain of the CMFB. The circuit employs positive feedback to enhance the output impedance and gain. The circuit has been designed using a 0.18 μ m CMOS technology under 1V supply and analyzed using HSPICE with BSIM3V3 device models. A pseudo-differential amplifier using two common sources and the proposed CMFB shows rail to rail output swing (± 0.7 V) with low common-mode gain (–36 dB) and power dissipation of 390 μ W.

In this paper, we analyze the diversity and multiplexing tradeoff (DMT) performance of fractional cooperative networks with three users in Rayleigh fading channels. We derive the precise DMT of both coded cooperation and space-time cooperation analytically. The DMT provides an upper bound for the achievable diversity gain corresponding to certain multiplexing gain. Our analysis reveals that both fractional cooperative schemes have the same DMT and the DMT performance varies with the exchange ratio defined as the ratio of the first phase to the entire transmission phase. A golden split exchange ratio of 0.618 is found to perform well from a practical implementation point of view.