Employing a triangular dielectric phase shifter simplifies the beam forming network of an offset beam array antenna because this structure achieves phase control in a single configuration. This paper proposes a design method for a low loss offset beam planar antenna that incorporates a triangular dielectric plate phase shifter on parallel microstrip feedlines. Our design method reduces the loss of the phase shifter by optimizing the microstrip line width. By using the proposed design equation, the optimum low loss phase shifter configuration can be easily established. In addition, this paper presents the actual design of a triangular plate considering size reduction. The results of experiments of the offset beam antenna indicate that our design method is effective in obtaining a simple, low loss, and compact configuration.

The design, fabrication, and characterization of monolithic analog phase shifters based on barium-strontium-titanate (BST) coated sapphire substrates with continuously variable 180and 360phase-shift ranges are presented. The phase shifter using a single series resonated termination can provide 180phase shift with the chip area of 4 mm 4 mm. A double series resonated termination in a parallel connection can reach over 370phase shift with better than 6.8 dB-loss at 2.4 GHz. Also, an all-pass network phase shifter composed of only lumped LC elements was described here. This phase shifter demonstrated 160phase shift with an insertion loss of 3.1 dB 1 dB and return loss of better than 10 dB at 2.4 GHz. The total size of the phase shifter is only 2.4 mm 2.6 mm, which is the smallest reported BST phase shifter operating at S-band, to the best of the authors' knowledge.

This paper reviews the antenna system for Japanese celullar systems and PHS (Personal Handphone System). The unique features of the Japanese cellualr system are multi-band operation, compact diversity antennas, electronic beam tilting, and indoor booster systems. The original antennas for the above purpose will be described. The PHS is also a unique mobile communication system in Japan, and is mainly used for high speed, low cost data transmission. Its original antennas are also presented in this paper.

This letter investigates sidelobe levels of a two-bit digital phased array composed of a small number of elements. Among several phase shifter designs applicable to phased arrays, a two-bit design needs the least number of circuit elements so that the development and manufacturing need the lowest cost. Now the following questions arise. Is a two-bit phased array practical? How low can its sidelobe level be reduced? To answer the questions, three methods are tried to reduce the sidelobe level of a uniformly-excited linear array of isotropic elements. The methods are the quadratic-phase feed method, the partially randomizing method of periodic phase errors, and the genetic algorithm (GA) approach. Among the methods, the quadratic-phase feed method provides the lowest sidelobe level around -12.5 dB - -13.2 dB in the steering angles from 0 to 48 degrees for a 21-element, half-wavelength spacing array, and -11.2 dB - -13.0 dB in the steering angles from 0 to 30 degrees for an 11-element, 0.6-wavelength spacing array. Although it depends on the system requirement, these values would be acceptable in some applications, hence a two-bit phased array designed properly may be practical in an actual system.

We describe the width conversion of an optical signal by using an erbium-doped fiber and an asymmetric optical circuit. The width of an optical signal was measured to be a respective 350 nsec and 200 nsec for a 70 m and 40 m fiber (Lf). The width of the pumping pulse was 5 nsec and the length of erbium-doped fiber was 3 m. We also extended the optical signals to a respective 300 nsec and 150 nsec wide at a pumping pulse 10 nsec by inserting a 60 m and a 30 m fiber (Lf) inside a circuit.

Broadband fixed wireless access (FWA) systems offer significantly higher bit rates than current cellular systems to which adaptive arrays are partly applied. Digital beam forming is being eagerly explored on account of its flexibility, but it will be difficult to apply to the high-speed systems, because its digital signal processing requires huge resources and power consumption. Conventional phased arrays, on the other hand, utilize phase shifters through RF or IF signal lines, but the phase shifters are usually both bulky and expensive. The authors propose an adaptive array steered by IF local signal phase shifters in this paper. The phase shift and the frequency shift of the signal from each antenna element can be simultaneously accomplished at the down conversion stage by the phase-controlled local signal. A prototype receiver operated in the K-band with the proposed configuration and its beam pattern measurement results are also described.

In this paper, a simple chaotic circuit using two RC phase shift oscillators and a diode is proposed and analyzed. By using a simpler model of the original circuit, the mechanism of generating chaos is explained and the exact solutions are derived. The exact expression of the Poincare map and its Jacobian matrix make it possible to confirm the generation of chaos using the Lyapunov exponents and to investigate the related bifurcation phenomena.

This paper presents closed form expressions to evaluate the average bit error rate (BER) of coherent binary phase shift keying (BPSK) and quadrature PSK (QPSK) systems in the presence of Nakagami-m fading channel and noisy phase reference. Performance degradation due to noisy phase reference is investigated versus both the fading parameter m and the maximum phase error φ. When m is increased from 1 to 9 and φ = 30, the degradation at the average BER of 10-3 for BPSK is increased from 0.3 dB to 0.48 dB. For φ increasing from 10 to 40 and m=5, the degradation is increased from 0.06 dB to 0.92 dB. Degradation thus increases with increasing φ and m.

A new manufacturing process for advanced Fiber Bragg Gratings which uses phase plates is described. Its high versatility allows to achieve many type of filters in optical fibers (phase-shifted, apodised, Fabry-Perot).

This paper describes a monolithic microwave integrated circuit (MMIC) active module with small phase variation and low insertion loss for beamforming network in S-band. The MMIC active module composed of a digital phase shifter, a digital attenuator and a buffer amplifier, has characteristic to control amplitudes and phase shifts by using digital control signals. By using the digital attenuator, the MMIC active module has obtained the excellent performances. This paper also describes the exact on-state resistance of FET switch for designing the digital attenuator.

A trinary-phased array, in which a phase quantization unit of phase shifters is 120 degrees is examined. The phase quantization unit of 120 degrees is the roughest value in practical phased array applications. Despite its rough phase quantization, the sidelobe level of less than -9 dB is attained by a genetic algorithm approach.

Phase performance in a fiber optic temperature sensor using a mode-division multiplex is studied. The phase shift due to the temperature change of a multimode graded-index optical fiber is analyzed. The intensity fluctuation by the interference of two modes is estimated in computer simulation.

This paper proposes a multiple open-loop frequency estimation scheme based on differential detection for M-ary phase shift keying (MPSK), which accomplishes fast initial acquisition, precise frequency estimation and wide frequency coverage at the same time. The proposed scheme, which has a good trade-off between complexity and performance, operates as follows: 1) it consists of several frequency error detectors (FEDs) based on differential detection with different delays; 2) it precisely estimates frequency in a wide range (the same range of one symbol differential detection) by open-loop according to frequency errors detected by the FEDs. For real-time symbol-by-symbol operation in order to track fast time-varying frequency, it has a smaller complexity than the other frequency estimation schemes. It is confirmed by analysis, numerical calculation and computer simulation that the frequency estimation error of the proposed scheme is close to the Cramer-Rao lower bound (CRLB) (asymptotic degradation of the proposed scheme from the CRLB is about 0. 5 dB) while keeping a wide frequency coverage and this scheme can track fast time-varying frequency.

This paper proposes a novel signal transmission scheme for helicopter satellite communications. The proposed scheme is based on time diversity, and combined with a novel algorithm to suppress an influence of carrier phase slip. In the proposed scheme, carrier phase slip is detected in cross correlation processing of the received signal, and is effectively suppressed. The proposed scheme thus makes it possible to employ coherent phase shift keying modulation to achieve bit error rate performance superior to that of differential phase shift keying modulation even in the low carrier-to-noise power ratio environment.

A novel phase compensation technique for feedback integrators is proposed. By the technique, a zero is obtained without employing extra capacitors. A design of an integrator for IC using the proposed technique is presented. The frequency of the parasitic pole is proportional to the unity gain frequency. It is shown that excess-phase cancellation is obtained at any unity gain frequency.

In this paper a novel narrow-band bandpass filter with an output pair of analytic signals is presented. Since it is based on the complex analog filter, both synthesis and response characteristics of this filter are different from conventional bandpass filters. In the design of this filter, the frequency shift method is employed and the conventional lowpass to bandpass frequency transformation is not required. The analysis and examples show that the output signal pair of the proposed filter possesses same filtering characteristics and a 90 degree phase shifting characteristics in the passband. Therefore, the proposed filter will be used for a single sideband (SSB) signal generator without quadrature generator.

An improved equivalent circuit model of a GaAs FET switch for MMIC phase shifters is proposed that incorporates distributed lines into a lumped-constant equivalent circuit to account for distributed-line effects. The validity of the proposed model is demonstrated by applying a coupled-wave analysis to the FET switch. Comparison of the measured and the simulated phase angles of the S-parameters shows that the improved model gives much bettter accuracy than the lumped-constant model. X-band six-bit MMIC phase shifters designed using the improved model are also described.

Approximate maximum likelihood (ML) detection implemented by a reduced state Viterbi algorithm (VA), called the reduced state Viterbi coherent detection (RSVCD) algorithm in this paper, is described for the reception of uncoded M-ary PSK (MPSK) signals transmitted over additive white Gaussian noise (AWGN) channels. An M-state trellis, each state representing one of M signal constellation points, is used. The RSVCD algorithm performs parallel channel estimation based on the per-survivor processing principle (PSPP). Simple decision feedback CD (DFCD) is deduced as a special case of RSVCD. Unified BER expressions are derived for RSVCD, DFCD, and approximate ML detection implemented as an ML-state Viterbi algorithm (referred to as VACD) [6] as well as ideal CD and differential detection (DD). Computer simulation results are also presented and compared with theoretical results.

A switched-capacitor phase-shifter oscillator of low distortion is discussed. The dc voltage related to the amplitude of oscillation was made for an automatic gain controller. The distortion factor was less than 0.5% in the frequency range from 100 µHz to 1 Hz.

This paper describes a novel quasi-transmission-line variable-reactance circuit that extends the variable-phase range of phase shifters. It consists of a transmission line and two shunt varactors. By appropriately choosing the characteristic impedance and electrical length of the transmission line, the variable-phase range can be significantly increased. Since the proposed circuit can be fabricated by the conventional MESFET process, a phase shifter can be integrated with other functional circuits. This enables fully monolithic integration of RF circuits as a one-chip multi-functional MMIC in radio communication systems. The variable-phase range of the prototype X-band monolithic phase shifter is 208 degrees, which is approximately four times as large as that of conventional one.