Search

A new ultra-wideband millimetre-wave passive balanced duplexer (DUX), employing a lumped-element Wilkinson power divider and grounded-centre-tap transformer, has been developed using 0.18- μ m BiCMOS process for fifth generation operations at 28, 37, 39 GHz, and beyond. The developed DUX is configured single-ended transmitter (TX) and antenna (ANT) ports and differential receiver (RX) port. It has an inherent matching at TX, RX and ANT ports, high TX–RX isolation, and highly balanced differential RX waveforms, and is ready for direct integration with a differential low-noise amplifier. Analysis has been performed to confirm the DUX's characteristics and assess its performance. Measured isolation from TX to each single-ended RX port is higher than 50 and 40 dB from dc-20 GHz and dc-60 GHz, respectively. Measured insertion loss from TX to antenna is better than 6.3 dB across 13–53 GHz. Measured insertion loss from ANT to differential RX port is lower than 13.8 dB from 25 to 57 GHz with 10.8 dB at 40 GHz. The core chip only occupies 0.3 mm2.

The design and implementation of a full-duplex radio system capable of real-time analogue self-interference cancellation at radio frequency (RF) and baseband stages are presented. The system consists of a dual-patch three-port orthogonally linear polarised antenna system (without a circulator/duplexer), a homodyne dual receiver, and a differential amplifier at the baseband. The interference outputs from the two receivers are equalised using a fixed attenuator and when they are passed through the differential amplifier at the baseband they are effectively cancelled. For the system reported the antenna system provides 45.1 dB isolation between transmit and receive ports over 60 MHz bandwidth centred at the operating frequency of 3.2 GHz. Interference cancellation achieved by the differential amplifier at the baseband reduces the total self-interference to 81.5 dB minimum at −5.6 dBm transmit power. Using the proposed system, the recovery of two different types of baseband signals in real time is demonstrated while the surrounding is multipath enabled. Since the self-interference at baseband is removed by the differential amplifier instead of a complex digital signal processing unit, it makes the proposed system suitable for broad-band millimetre-wave full-duplex transceivers where the use of analogue/digital converter is not an option.

This study presents the first monolithically integrated full-duplex front-end for K/Ka satellite communication phased arrays. A 0.25 μm SiGe:C BiCMOS process was used to develop the integrated circuit. The receive and transmit channels are united into a common port through a novel duplexer. For each RF channel, the bias currents, the active channels and the power amplifier operation mode can be controlled through a serial bus. Amplitude and phase control are provided with fine granularity (65,536 states). In transmit mode, each channel provides 37.3 dB of gain with 12.9 dBm output power at 1-dB compression. In receive mode, 33.7 dB gain is measured with a noise figure of 3.2 dB. The amplitude/phase root-mean-square errors within the transmit (29.5–30.8 GHz) and receive (19.7–21 GHz) bands are below 0.7 dB/ 6.4 ° and 0.26 dB/ 1.1 ° , respectively. The chip occupies 1.64 × 3.5 m m 2 and it consumes 81 and 15.5 mW per transmit and receive channels, respectively. The use of a Doherty power amplifier with a novel dynamic adaptive bias circuit led to a 31% reduction of the total dc array power consumption.

Practical methods to mitigate level and variation of passive intermodulation with respect to time and temperature of coaxial cavity type duplexer are proposed through a variety of experimental results. From the findings derived in this study, a stable passive intermodulation response with less than 1 dB variation was shown in the environment temperature range of −10–85 °C. The duplexer with time‐stable PIM response at room temperature had a stable PIM value even in the environment temperature range.

In this study, the design and analysis of a seven-port radar duplexer for tracking a target in X-band operation are presented. The S-parameters of the structure are calculated and compared with experimental results. The simulations and experimental results are in good agreement. This device enables radars to calculate the horizontal difference, vertical difference, and sum of four beams of a monopulse antenna based on amplitude discriminator. Three magic-Ts and one T-junction are used, four input ports are connected to a monopulse antenna and three other ports are output ports. The output data give three equations between input signals that allow the radar to track a target. Results show that the S-parameters of this device are affected by magic-Ts and the T-junction structure, and an optimum structure for the magic-Ts and T-junction is proposed. A comprehensive study has been carried out for determination and comparison of properties of the structure in theory, simulation, and experimental results. This device is useful in radar tracking systems.

This study presents a shared structure for both near- and far-field operations using magnetic resonance coupling and electromagnetic radiation. The proposed structure is composed of a rectangular loop and two monopoles. A duplexer is designed to route the near- and far-field signals. For far-field operation, both dual-band resonance and dual-sense circular polarisation required by the compass navigation satellite system (CNSS) are achieved. For near-field operation, a wireless communication link operating at 13.56 MHz is established. The effect of matching distance on the transmission performances is studied and the optimal matching network is obtained. The proposed design is fabricated and verified experimentally. In the far-field regime, it can achieve 10 dB impedance bandwidths of 17.2 and 15.8% and 3 dB axial ratio bandwidths of 4.6 and 12.8% and the two CNSS bands are fully covered. In the near-field regime, an average transmission coefficient of 0.59 is achieved within the operation range of 5-30 mm by the proposed design. The obtained good performance reveals that the proposed shared structure is suitable to be applied in handheld devices for near-field communication and CNSS applications.

A type of wide-band signal-interference planar duplexer with single- and dual-band channels is presented. It exploits transversal-signal-interference-section-based channels with contiguous single- and dual-passband filtering transfer functions. Furthermore, by ending the dual-band channel in a reference-impedance resistor, a wide-band bandpass filter (BPF) with quasi-absorptive stopbands is realised. As experimental validation, microstrip prototypes of a duplexer and a two-stage quasi-absorptive BPF that operate in the 1.6–4.4 GHz range are built and tested.

A novel topology for designing 60 GHz duplexers is presented. Both the receiver (Rx) and transmitter (Tx) filters of the duplexer, which were constructed using dual-mode substrate-integrated waveguide (SIW) cavities, can exhibit a single-sided transmission zero. The transmission zeros were arranged to achieve high channel isolation and frequency selectivity. The results confirm that the fabricated duplexer can achieve an Rx/Tx isolation higher than 30 dB.

The design and implementation of dual-band duplexers is presented. The proposed method works well for duplexers with narrow bandwidths and it gives the designers the flexibility to achieve desired return loss levels at different frequency bands. To verify the design concept, dual-band duplexers based on cavity-type resonator topologies are designed, fabricated and tested. Good agreement is achieved between the theoretical synthesis results, the simulation results and the measurement results of the duplexer prototype.

A novel method of miniaturising the size of a coaxial cavity resonator by utilising zeroth-order resonance (ZOR) characteristics is presented. This miniaturisation has been achieved through the introduction of air-core coils inside a conventional coaxial cavity resonator. This structure possesses ZOR characteristics, which results in the miniaturisation of the resonator while still exhibiting a reasonable high unloaded Q factor. A duplexer was designed and fabricated using the proposed resonator. The measurement results verified that a 30% reduction in size was achieved compared with a traditional duplexer.

The implementation of an active transceiver patch antenna without duplexer is reported. The isolation of the transmitting-receiving ports is increased by almost 20 dB by using defected ground structure patterns obtaining more than 50 dB; besides, cross-polarisation levels are also decreased by more than 15 dB. On the other hand, the use of spur lines allows increasing the linearity of the transmitting path, obtaining a low-harmonic distortion class E power amplifier. In the receiving path, a high-linear low noise amplifier (LNA) is employed with a third-order input intercept point close to 20 dBm. Both amplifiers are built with heterounion bipolar transistor (HBT). To prove the idea, as an example, the operation frequencies and channel separation of the GSM1800 were taken into account for a practical design. The complete active antenna is developed with characteristic impedances different from 50 Ω to obtain optimal performance of the active blocks.

A method to design a microstrip filter has been proposed. The multiple capacitively loaded coupled lines are adopted for the design of the microstrip filter. The filter shows different stopband behaviour with respect to even or odd total number of resonators. The transmission zeros may be located around the lower, higher or both regions of the passband's skirt. The coupling among the capacitively loaded lines can produce another transmission zero particularly in the higher stopband. A bandpass filter and a duplexer utilising these features are designed. The equivalent model is also proposed to illustrate the filter's coupling among these capacitively loaded coupled lines. The design has been verified by experimental results.

An improved continuous-time sigma-delta (ΣΔ) architecture with elliptic signal transfer function is presented. It is demonstrated that the UTRA/FDD band 1 interferer filtering can be fully achieved within the sigma-delta loop.

The authors report the design and first realisation of a grating-assisted horizontal directional coupler filter exhibiting a highly reduced polarisation sensitivity (below 1 dB on the filtered channel) and a high sidelobe suppression ratio (>25 dB for both polarisations). This filter is particularly suitable for integration in a 1.3/sup +//1.3/sup -/ /spl mu/m duplexer.

A successful design for a sum/difference beam duplexer used as the feed network of a coupled tapered slot-line antenna (CTSA) is presented. VSWR/spl les/1.5:1 was obtained at both the sum and difference ports over the 33.4-36.0 GHz frequency range. An isolation of -25.0 dB was obtained between the sum and difference ports over the range 33.2-37.6 GHz.

The fabrication and characterisation of monolithically integrated OEIC transceivers for use in optical subscriber access links are reported. A design incorporating DFB lasers, wavelength duplexers and a monitor photodiode, specific to the TPON/BPON passive optical network configuration is presented.

An ultra-miniature duplexer (5 × 8 × 2.2 mm3) consisting of two FBAR filters and nine passive components operating at 1900 MHz is described. The minimum insertion loss for the Tx and Rx bands is better than –3 dB. Isolation between the Tx and Rx ports exceeds 50 dB over most of the Tx band and 46 dB in the Rx band. The FBAR filters handle up to 2 W throughout the passband.

The design and realisation on InP of a meander-type grating-assisted codirectional coupler optical filter exhibiting a 40 nm box-like spectral response with high sidelobe suppression and reduced anisotropy is reported. A thermal tuning range larger than 20 nm is electrically realised.

A power amplifier combined with duplexer is presented for the CDMA-based PCS phone. For reducing idle currents and the overall size of the combined module, dielectric filters in the duplexer are rearranged into a power amplifier to reduce the output power level of the module. The DC bias point is limited to class B. About a 50 mA idle current has been successfully saved, and more current has been saved in the hand phone owing to the reduced power level of the module. The module size has been reduced to 1.5 CC. ACPR performances are satisfactory at the maximum output power of a power amplifier required by IS-95 air interface standards.

Cellular mobile radio operates in full duplex mode, e.g. simultaneously transmits and re ceives radio frequency signals. A duplexer is constructed with a transmitter final stage filter (T1) and a receiver top filter (R1). New SAW filters using an extended SAW-resonator-coupled structure have been developed for Japanese cellular radio. A low loss of 1.6 dB for T1 and a high rejection level of 50 dB for R1 have been achieved.

The design and fabrication of OEICs on semi-insulating InP substrates comprising 1300 nm DFB lasers, 1300/1530 nm wavelength duplexers and monitor photodiodes is described. OEIC lasing thresholds were as low as 20 mA. The through-state crosstalk for the integrated duplexer was typically -12 dB. Linear tracking of the laser output by the monitor photodiode was achieved with sensitivities in the region of 70 mu A/mW. The OEICs operated successfully in a 622 Mbit/s bidirectional optical link.

A simple and broadband orthomode transducer (OMT) is presented. It can be machined or moulded in two almost identical parts which implies a potentially cheap design. Both the mechanical construction and the prin- ciple of operation are described. The paper also presents results both from some preexperimenta- tions and for the complete OMT. These results show that the isolation between the ports for the complete OMT is better than approximately 50 dB and the return loss less than -- 20 dB in the frequency range lO.Gl5.0 GHz.

We discuss the design of Mach-Zehnder wavelength duplexers for 1300 nm and 1530 nm band-centres using InGaAsP/InP strip-loaded waveguides. We show that this device has a high inherent tolerance to fabrication and waveguide parameter variation and is therefore particularly suitable for ‘dead-reckoned’ fabrication in a low-cost optoelectronic transceiver chip for local area fibre networks. Using a novel configuration of concentrically curved waveguides, crosstalk better than —11.75 dB has been achieved in both channels. The performance of the constituent waveguide bends and directional couplers is also discussed.

A new form of microwave pulsed attenuator for use in duplexing systems is described. The use of an r.f.-excited gas discharge avoids many of the problems inherent in other forms of pulsed attenuator and results in a simple, inexpensive and reliable component. One form of attenuator, for the 3000 Mc/s frequency band, is described in detail, and its performance is discussed in relation to the overall system performance of a microwave duplexer. An attenuation of at least 50 dB with a recovery time of 25–30 microsec to 6 dB is achieved. The bandwidth of the attenuator depends on the number of resonant elements used; with an attenuator consisting of four resonant elements two of which contain discharge tubes, a bandwidth of at least 10% to a voltage standing-wave ratio of 0.85 may be obtained. The insertion loss of the complete attenuator is less than 0.1 dB.The application of the same principles to the design of pulsed attenuators at other microwave frequencies is discussed.

Consideration is given to the v.h.f. transmission of stereophonic programmes, restricted to f.m. transmitters with a sub-carrier system. Criteria are given, indicating the superiority of the so-called double f.m. system, which has a much smaller deviation than usual of the main carrier due to the sub-carrier, the deviation of which is reduced to only 15 kc/s. A circuit description is given of both the transmitter duplexer and the adaptor necessary for ordinary f.m. receivers. Special attention has been paid to applications of sub-carrier systems other than for stereophony. These lead to more stringent requirements for the crosstalk attenuation.

Research into a novel class of distributed amplifiers which have a high isolation bandstop response in the reverse gain direction is described. These devices may be used as duplexer/circulator or bidirectional amplifier elements which, for many applications, can perform the function of ferrite isolator and circulator elements. The paper details the design of such an amplifier, working in the S-band, and gives measured test data.

The paper describes a compact L-band duplexer capable of handling peak powers in the megawatt range. It uses a hybrid waveguide/coaxial construction in which the transmitter power is fed through the waveguide section and the received signal is coupled out by a coaxial probe. A simplified theoretical analysis is included in the paper which predicts the loss and power-handling capacity of the circuit. Measured results are presented for an experimental device operating in the 1.25-1.35 GHz which indicate a transmitter-channel loss of less than 0.2 dB, and a receiver-channel loss of less than 0.5 dB for a 28 dB isolation level. Zusammenfassung: Es wird die Entwicklung eines kompakten L-Band Duplexers beschrieben, bei dem die Sendeleistung durch einen Hohlleiter, die Empfangsleistung aber durch ein Koaxteil geschaltet wird. Eine vereinfachte theoretische Betrachtung zeigt eine gute Ubereinstimmung mit den gemessenen Daten. Messungen an einem Labor-Muster zeigen eine Durchlasdampfung von ca. 0.5 dB und eine Sperrdampfung von ca. 28 dB uber eine Bandbreite von ca. 10% bei 1.3 GHz. Die Leistungsfestigkeit betrug uber 700 kW bei einer Pulslange von 5 μs und einem Tastverhaltnis von 1: 500.

The objects of this work were to investigate the extent of rain clutter using 8-mm continuous-wave radar systems with both a single aerial (common transmission and reception) and dual aerials (separate transmission and reception) and to investigate the reduction of this clutter by orthogonal polarization techniques. In the common transmission and reception case using polarization duplexing, the amplitude of the rain clutter was measured in terms of decibels below the valve power level by a direct comparison method and plotted against the rainfall rate in millimetres per hour. This was also done for the separate transmission and reception case, which did not employ a duplexer. The results showed that the rain clutter amplitude in the common transmission and reception case was some 60 db below valve power level for a moderate rainfall of 3 mm/h. In the separate transmission and reception case rain clutter decreased with increasing aerial spacing and was some 95 db below valve power for a rainfall rate of 3 mm/h with 2-ft diameter aerials spaced 3 ft centre to centre. Details of the methods of measurements, the equipment used and the experimental observations are given.