Standard Microstrip Research Articles

Improvement of a bit error rate measuring system for high-temperature superconducting circuits

We have evaluated and tried to improve the measurement precision of a bit error rate (BER) measuring system for superconducting circuits equipped with a magnetic shield and a cryocooler. A noise model has suggested that the most effective way of improving BER is to reduce the noise figure of the wideband pulse amplifier (WPA). BER measurement using a 3-Gbps, 2/sup 15/-1 pseudo random binary signal showed that by using low-noise WPA (noisefigure=4 dB) a 12.0-mV output voltage is required to obtain a minimum BER of 1.19/spl times/10/sup -15/ (a 10/sup -7/ improvement over the previous system) for a 50 /spl Omega/ standard microstrip. A BER of a La/sub 0.2/Yb/sub 0.9/Ba/sub 1.9/Cu/sub 3/O/sub x//MgO/Au microstrip-line to coplanar-waveguide transition-line converter (MCC) was also measured. It was found that the minimum BER was 4.87/spl times/10/sup -13/ (a 10/sup -5/ improvement over the previous system) when the output voltage was 23.8-mV. However these measured BER values were larger than those expected by the noise model. The cause of the larger measured BER is discussed. A minimum BER of 3.64/spl times/10/sup -55/ in 14.8-mV output voltage for a 50 /spl Omega/ standard microstrip was obtained when the cryo-cooler was not operated (without the noise from a cryo-cooler).

Design of broadband and dual-band microstrip antennas on a high-dielectric substrate using a genetic algorithm

The authors report the use of a genetic algorithm (GA) to design patch shapes for microstrip antennas on a high-dielectric substrate for broadband and dual-band applications. A full-wave electromagnetic solver is employed to predict the performance of microstrip antennas with arbitrary patch shapes. A two-dimensional chromosome is used to encode each patch shape into a binary map. A GA with a two-point crossover and geometrical filtering is implemented to achieve efficient optimisation. The resulting optimised patch structures for broadband and dual-band operations are described. For broadband application, the optimised patch antenna achieves a four-fold improvement in bandwidth when compared to a standard square microstrip antenna. For dual-band application, the optimised patch antenna shows a good impedance match at the design frequencies of 1 and 2 GHz. The GA-optimised designs are built on a FR-4 substrate and measurement results show good agreement with the numerical prediction. Physical interpretation for the optimised shapes is discussed.

Dual‐port dual‐polarized microstrip antenna

AbstractExperimental and simulated results for a dual‐port dual‐polarized microstrip antenna are presented. The antenna excites two orthogonally polarized resonant frequencies providing an isolation of ∼30 dB between the ports. The patch geometry consists of two circular arcs of different radii with their centers displaced by a distance. This new design offers an area reduction of ∼70% compared to a standard rectangular microstrip antenna with a reduction in gain of 1.7 dB. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 459–460, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10494

Compact circular‐sided microstrip antenna for circular polarization

AbstractDevelopment of a new compact circular‐sided microstrip antenna is presented. This antenna offers considerable area reduction compared to standard rectangular microstrip antenna designed for the same frequency. Typical antenna design and experimental results for circular polarization are also demonstrated. The antenna has a 3‐dB axial ratio bandwidth of 1.5%. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 176–177, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10408

A novel U-shaped planar microstrip antenna for dual-frequency mobile telephone communications

We present a novel configuration of a U-shaped dual-frequency single feeding port planar inverted-F microstrip antenna for mobile communication applications in both the GSM and DCS 1800 systems operated at 0.9 and 1.8 GHz, respectively. Starting from an initial design derived from an empiric approximation and transmission line model for a standard rectangular microstrip antenna, we analyze, tune, and optimize the electric performance of the antenna and its dimensions by means of the generalized nonuniform finite-difference time-domain (NU-FDTD) Maxwell's solver.

Bit error rate measurement of a high-speed small-voltage signal using a superconducting transmission line

We developed a measuring system that has a magnetically shielded wide-band test fixture mounted on a closed-cycle cryo-cooler, and used this system to investigate the feasibility of cryo-packaging technology for high-Tc superconducting digital electronics. In this work, we evaluated the bit-error-rate (BER) performance of a system in which was installed a 50-/spl Omega/ standard microstrip line (MSTL) and a YBa/sub 2/Cu/sub 3/Ox microstrip line to a coplanar waveguide (CPW) transmission line converter (MCC). In the experiment, we used 3-Gbps, 2/sup 15/-1 pseudo-random binary sequence (PRBS) signals. The temperature of the test fixture was 20 K. Results showed that the BER was 3.74/spl times/10/sup -9/ for the 50-/spl Omega/ MSTL when the signal amplitude at the sample was 13.3 mV, and 1.52/spl times/10/sup -9/ for the MCC when the amplitude was 30.8 mV. The effect of the signal loss and impedance mismatch on the BER is also discussed.

A method for the prediction of microwave properties of thick film conductors from physical measurements and d.c. conductivity

It is theoretically possible to calculate electrical losses in conductors at high frequencies using standard microstrip equations. To do this it is necessary to know the length, width and surface roughness of sample tracks. The sheet resistance at d.c. is replaced with a new term, surface resistance which is the bulk resistivity divided by the skin depth at the frequency under consideration. The paper looks at the relationship between these predictions and measured results. A wide range of commercial thick film conductors has had its physical properties measured and a comparison made with the figures for idealized structures. The paper contains a discussion on the differences between real and ideal materials. It was seen that the predictions were close to the measured results at lower frequencies, but that there was divergence as the frequency approached 15–20 GHz. For low-cost applications it is generally considered that economically viable conductors will be unsuitable for microwave applications. However, the paper discusses whether some of the lesser used conductors, such as fritted silver, could have an application in low-cost microwave devices, for example alarm systems. © 2001 Kluwer Academic Publishers

Shape optimisation of broadband microstrip antennasusing genetic algorithm

The genetic algorithm (GA) is used to design patch shapes for microstrip antennas on FR-4 substrate for broadband applications. Measurement results of the GA-optimised designs show good agreement with numerical prediction. The optimised patch design achieves a fourfold improvement in bandwidth when contrasted with a standard square microstrip antenna.

The virtual cathode chamber

We describe the operating principle and the first experimental results obtained with gas micro-strip detectors realized with anodes only on the active side, the multiplying field being provided from the back-plane and drift electrodes. For high-rate operation, the detector has to be implemented on electron-conducting supports, with resistivity around 10 11 Ω cm. By construction, the “Virtual Cathode Chamber” is not subjected to the possibility of discharges between anodes and cathodes, thus avoiding one of the most dangerous problems met with standard micro-strip chambers.

Beam test results with the silicon pad detector

A silicon pad detector, consisting of 16 × 16 silicon diodes (150 × 150 μm pitch), with an integrated fan-out which allows readout using standard micro-strip detector front end electronics, was connected to VA2 low noise chips. The performance of the system with a measured Equivalent Noise Charge of 80 electrons can be compared with realistic pixel detectors for future particle physics experiments. In this work we present detailed experimental study of the charge collection mechanism and the spatial resolution as a function of the impact angle of traversing particles at a 100 GeV test beam at CERN. Comparison with a binary readout scheme, realistically simulated using analog information from our measurements, is done.

Correlations Between YBa2Cu3O7-δ Thin Film Materials Properties and RF Device Performance

ABSTRACTBetter knowledge of the relationships between YBa2Cu307-δ (YBCO) materials properties and the RF performance of devices made from these materials should lead to improved device performance and yields. A variety of materials tests were performed on our production YBCO films which were patterned into standard microstrip resonators. The materials parameters were then compared with the unloaded Q of the resonators at 77 K. As expected, films with higher Q's tended to have higher Tc, higher Jc, greater film thickness, and better crystallinity. The last was based on narrower YBCO rocking curve peak, lower second phase density (judged by lower resistivity and greater θ-2θ (005) peak area), and a narrower θ-2θ (005) peak. The room temperature sheet resistance was found to be a useful predictor of microwave performance for films that are otherwise similar.

Broadband dual frequency microstrip antenna

A new dual port microstrip antenna geometry for dual frequency operation is presented. The structure consists of the intersection of two circles of the same radius with their centres displaced by a small fraction of the wavelength. This antenna provides wide impedance bandwidth and excellent isolation between its ports. The gain of the antenna is comparable to that of a standard circular microstrip antenna operating at the same resonant frequency. A theoretical analysis for calculating the resonant frequencies of the two ports is also presented.

Proposed ultrahigh frequency microstrip utilising buried silicide groundplane

Recently it has become possible to produce buried singlecrystal silicide layers in silicon on which epitaxial silicon may be grown. We show that if such a layer is used as a groundplane in a microstrip configuration, ultra-high-speed signals (e.g. 100 GHz) can be propagated with far less dispersion than on standard microstrip, by virtue of the close proximity of the groundplane to the centre conductor.

The SSFIP: a global concept for high-performance broadband planar antennas

The SSFIP (strip-slot-foam-inverted patch) antenna presents significant advantages over standard microstrip antennas: very broad bandwidth, high efficiency, low crosspolarisation level, integrated radome, lightweight and rigid construction and low cost. A 16-element array with more than 16dB gain and 21.1% bandwidth for SWR≤2 shows what can be achieved.

Microstrip dispersion

Microstrip transmission lines used in microwave integrated circuits are dispersive. The dispersion of the lines is fully characterized by the frequency-dependent normalized phase velocity VP which is equal to the ratio of guide wavelength λ g to free-space wavelength λ 0 . An approximate equation is given for the normalized phase velocity VP and for the frequency-dependent line impedance Z for standard microstrip transmission lines. Comparison with available experimental data and computed data shows that the error of the approximation is less than 3 percent for microstrip transmission lines commonly used in engineering applications.