CiteULike: dcastro's bandwidth

Noise Bandwidth of Common Filters

R Shelton — 2008-05-30T10:23:12-00:00

Communications, IEEE Transactions on [legacy, pre - 1988], Vol. 18, No. 6. (1970), pp. 828-830.

The noise bandwidth B<inf>N</inf>of Butterworth, Bessel, and Chebyshev filters is tabulated. The Butterworth filter is shown to have the minimum B<inf>N</inf>to 3-dB bandwidth ratio for any secondorder filter. It is proven that B<inf>N</inf>is invariant when a low-pass to bandpass transformation is made. An error is corrected in recent tables of Chebyshev filters.

Simple approximate formulas for input resistance, bandwidth, and efficiency of a resonant rectangular patch

DR Jackson — 2008-05-27T07:10:39-00:00

Antennas and Propagation, IEEE Transactions on, Vol. 39, No. 3. (1991), pp. 407-410.

Simple approximate formulas for the input resistance, bandwidth, and radiation efficiency of a resonant rectangular microstrip patch are derived. These formulas become increasingly accurate as the substrate thickness decreases. Because the formulas are derived from approximations of a rigorous Sommerfeld solution, they provide insight into the effect of the substrate parameters on the patch properties, in addition to providing approximate design equations

Bandwidth efficient parallel concatenated coding schemes

S Benedetto — 2008-05-26T13:56:44-00:00

Electronics Letters, Vol. 31, No. 24. (1995), pp. 2067-2069.

The authors propose a solution to the parallel concatenation of trellis codes with multilevel amplitude/phase modulations and a suitable iterative decoding structure. Examples are given for throughputs 2bit/s/Hz with 8PSK and 16QAM signal constellations. For parallel concatenated trellis codes in the examples, rate 2/3 and 4/5, 16-state binary convolutional codes with Gray code mapping are used. The performances of these codes are within 1 dB of the Shannon limit at a bit error probability of 10<sup>-6</sup> for a given throughput. This outperforms all codes reported in the past for the same throughput

On Impedance Bandwidth of Resonant Patch Antennas Implemented Using Structures With Engineered Dispersion

PMT Ikonen — 2008-05-18T14:05:13-00:00

Antennas and Wireless Propagation Letters, IEEE, Vol. 6 (2007), pp. 186-190.

In this letter, we consider resonant patch antennas, implemented using loaded transmission-line networks and other exotic structures having engineered dispersion. An analytical expression is derived for the ratio of radiation quality factors of such antennas and conventional patch antennas loaded with (reference) dielectrics. In the ideal case this ratio depends only on the propagation constant and wave impedance of the structure under test, and it can be conveniently used to study what kind of dispersion leads to improved impedance bandwidth. We illustrate the effect of dispersion by implementing a resonant patch antenna using a periodic network of lumped reactive (LC) elements. The analytical results predicting enhanced impedance bandwidth compared to the reference results are validated using a commercial circuit simulator. Discussion is conducted on the practical limitations for the use of the proposed expression

A new approach to gain-bandwidth problems

H Carlin — 2008-05-12T06:27:40-00:00

Circuits and Systems, IEEE Transactions on, Vol. 24, No. 4. (1977), pp. 170-175.

A new idea for treating the broad-band matching of an arbitrary load to a resistive generator leads to a simple technique for the design of a lossless 2-port equalizer. The method is a numerical one, and only utilizes real frequency (e.g., experimental) load impedance data. No model or analytic impedance function for the load is necessary. Nor is the equalizer topology or analytic form of the system transfer function assumed. The arithmetic is well conditioned and the intricacies of gainbandwidth theory are bypassed. An example comparing the method with analytic gain-bandwidth theory is given. Two examples proceeding directly from experimental data are presented. One is the broad banding of a microwave avalanche diode reflection amplifier. The other is the gainbandwidth equalization of a microwave FET amplifier for gain taper and impedance mismatch.

A low-noise phase-locked loop design by loop bandwidth optimization

Kyoohyun Lim — 2008-05-10T14:39:00-00:00

Solid-State Circuits, IEEE Journal of, Vol. 35, No. 6. (2000), pp. 807-815.

This paper describes a low-noise phase-locked loop (PLL) design method to achieve minimum jitter from a given PLL circuit topology. An optimal loop-bandwidth design method, derived from a discrete-time PLL model, further improves the jitter characteristics of a PLL already somewhat enhanced by optimizing individual circuit components. The described method not only estimates the timing jitter of a PLL, but also finds the optimal bandwidth minimizing the overall PLL jitter. A prototype PLL fabricated in a 0.6-μm CMOS technology is tested. The measurement shows significant performance improvement by using the proposed method, The measured rms and peak-to-peak jitter of the PLL at the optimal loop-bandwidth are 3.1 and 22 ps, respectively

A novel approach for gain and bandwidth enhancement of patch antennas

Yongxi Qian — 2008-05-09T06:44:33-00:00

Radio and Wireless Conference, 1998. RAWCON 98. 1998 IEEE (1998), pp. 221-224.

The microstrip patch is one of the most preferred antenna structures for low-cost and compact design of wireless communication systems and RF sensors. To overcome several intrinsic limitations of the patch antenna such as narrow bandwidth, low gain, and degradation of radiation efficiency at higher frequencies, we propose a novel technique for gain and bandwidth enhancement based on the photonic band-gap (PBG) concept. The Ku-band prototype demonstrates over 3 times bandwidth improvement, and 1.6 dB higher gain or 45% increase in effective radiated power (ERP), compared with a regular patch with identical dimensions. System design issues such as co-site interference can also be alleviated by the improved beam patterns of the new PBG antenna

Bandwidth-efficient turbo trellis-coded modulation using punctured component codes

P Robertson — 2007-12-02T09:23:56-00:00

Selected Areas in Communications, IEEE Journal on, Vol. 16, No. 2. (1998), pp. 206-218.

We present a bandwidth-efficient channel coding scheme that has an overall structure similar to binary turbo codes, but employs trellis-coded modulation (TCM) codes (including multidimensional codes) as component codes. The combination of turbo codes with powerful bandwidth-efficient component codes leads to a straightforward encoder structure, and allows iterative decoding in analogy to the binary turbo decoder. However, certain special conditions may need to be met at the encoder, and the iterative decoder needs to be adapted to the decoding of the component TCM codes. The scheme has been investigated for 8-PSK, 16-QAM, and 64-QAM modulation schemes with varying overall bandwidth efficiencies. A simple code choice based on the minimal distance of the punctured component code has also been performed. The interset distances of the partitioning tree can be used to fix the number of coded and uncoded bits. We derive the symbol-by-symbol MAP component decoder operating in the log domain, and apply methods of reducing decoder complexity. Simulation results are presented and compare the scheme with traditional TCM as well as turbo codes with Gray mapping. The results show that the novel scheme is very powerful, yet of modest complexity since simple component codes are used

An impedance-matching technique for increasing the bandwidth of microstrip antennas

HF Pues — 2008-04-15T17:46:22-00:00

Antennas and Propagation, IEEE Transactions on, Vol. 37, No. 11. (1989), pp. 1345-1354.

The nature of the inherent narrow bandwidth of conventional microstrip patch antennas is considered. It is observed that, except for single-feed circularly polarized elements, their bandwidth is limited only by the resonant behavior of the input impedance and not by radiation pattern or gain variations, which usually are negligible over a moderate 10 to 20% bandwidth. Therefore, broadband impedance matching is proposed as a natural to increase the bandwidth. The maximum obtainable bandwidth is calculated using Fano's broadband matching theory. It is found that by using an optimally designed impedance-matching network, the bandwidth can be increased by a factor of at least 3.9, the exact value depending on the degree of matching required. A transmission-line prototype for a proper matching network is developed. The translation of this prototype network into a practical structure (e.g. a microstrip or stripline circuit) is considered. Practical design examples and experimental results which clearly show the validity of the technique are given

Correlation Bandwidth and Delay Spread Multipath Propagation Statistics for 910-MHz Urban Mobile Radio Channels

D Cox — 2008-04-15T10:35:40-00:00

Communications, IEEE Transactions on [legacy, pre - 1988], Vol. 23, No. 11. (1975), pp. 1271-1280.

Distributions of delay spread and correlation bandwidth at 0.9 and 0.5 correlation for Gaussian wide-sense stationary uncorrelated scattering (GWSSUS) channels associated with 100 small-scale areas at different locations within a 2 × 2.5 km region of New York City are presented. For delay spread the maximum value observed was<tex>3frac12;mu</tex>s and l0 percent of the areas exceeded<tex>2frac12mu</tex>s; for correlation bandwidth at 0.9 correlation the minimum was 20 kHz and 10 percent of the areas were less than 30 kHz; for correlation bandwidth at 0.5 correlation the minimum was 55 kHz and 10 percent of the areas were less than 130 kHz. The region is representative of the heavily built-up areas of many large cities in the United States.

Impedance, bandwidth, and Q of antennas

AD Yaghjian — 2008-02-26T19:59:09-00:00

Antennas and Propagation, IEEE Transactions on, Vol. 53, No. 4. (2005), pp. 1298-1324.

To address the need for fundamental universally valid definitions of exact bandwidth and quality factor (Q) of tuned antennas, as well as the need for efficient accurate approximate formulas for computing this bandwidth and Q, exact and approximate expressions are found for the bandwidth and Q of a general single-feed (one-port) lossy or lossless linear antenna tuned to resonance or antiresonance. The approximate expression derived for the exact bandwidth of a tuned antenna differs from previous approximate expressions in that it is inversely proportional to the magnitude |Z'/sub 0/(/spl omega//sub 0/)| of the frequency derivative of the input impedance and, for not too large a bandwidth, it is nearly equal to the exact bandwidth of the tuned antenna at every frequency /spl omega//sub 0/, that is, throughout antiresonant as well as resonant frequency bands. It is also shown that an appropriately defined exact Q of a tuned lossy or lossless antenna is approximately proportional to |Z'/sub 0/(/spl omega//sub 0/)| and thus this Q is approximately inversely proportional to the bandwidth (for not too large a bandwidth) of a simply tuned antenna at all frequencies. The exact Q of a tuned antenna is defined in terms of average internal energies that emerge naturally from Maxwell's equations applied to the tuned antenna. These internal energies, which are similar but not identical to previously defined quality-factor energies, and the associated Q are proven to increase without bound as the size of an antenna is decreased. Numerical solutions to thin straight-wire and wire-loop lossy and lossless antennas, as well as to a Yagi antenna and a straight-wire antenna embedded in a lossy dispersive dielectric, confirm the accuracy of the approximate expressions and the inverse relationship between the defined bandwidth and the defined Q over frequency ranges that cover several resonant and antiresonant frequency bands.

Synthesizing Microstrip Branch-Line Couplers With Predetermined Compact Size and Bandwidth

CW Tang — 2007-12-06T16:52:53-00:00

Microwave Theory and Techniques, IEEE Transactions on, Vol. 55, No. 9. (2007), pp. 1926-1934.

<para> A new method for designing the microstrip branch-line couplers with predetermined compact size and bandwidth is proposed in this paper. With the proposed approach, the size of the quarter-wavelength transmission line in the branch-line coupler can be reduced greatly. In addition, the proposed couplers can be easily fabricated on the printed circuit board without any lumped element. A chart concludes the relationship between bandwidth and size reduction rate. It shows that open stubs with low impedance perform better than those with high impedance; moreover, the more open stubs with low impedance utilized, the broader the bandwidth will be. Furthermore, the measured frequency responses show good agreement with the theoretical results. </para>