In general, Micropower Impulse Radar (MIR) depends on Ultra-Wideband (UWB) transmission systems. UWB technology can supply innovative new systems and products that have an obvious value for radar and communications uses. Important applications include bridge-deck inspection systems, ground penetrating radar, mine detection, and precise distance resolution for such things as liquid level measurement. Most of these UWB inspection and measurement methods have some unique qualities, which need to be pursued. Therefore, in considering changes to Part 15 the FCC needs to take into account the unique features of UWB technology. MIR is applicable to two general types of UWB systems: radar systems and communications systems. Currently LLNL and its licensees are focusing on radar or radar type systems. LLNL is evaluating MIR for specialized communication systems. MIR is a relatively low power technology. Therefore, MIR systems seem to have a low potential for causing harmful interference to other users of the spectrum since the transmitted signal is spread over a wide bandwidth, which results in a relatively low spectral power density.

/pdf/response-to-fcc-98-208-notice-of-inquiry-in-the-matter-of-3attixctl7.pdf

Response to FCC 98-208 notice of inquiry in the matter of revision of part 15 of the commission's rules regarding ultra-wideband transmission systems

Ultrawideband (UWB) that is regulated by the Federal Communications Commission (FCC) for short-range high-throughput wireless communication and sensor networks with advantageous features, such as immunity to multipath fading, extremely short time duration, being carrier free, and having low duty cycle, wide bandwidth, and low power spectral density, has been a topic of interest recently. By wireless transmission, UWB communications systems can only operate in a short distance of a few meters to tens of meters. The convergence of UWB and optical fiber distribution techniques, or UWB over fiber, offers the availability of undisrupted service across different networks and eventually achieves high-data-rate access at any time and from any place. To distribute the UWB signals over the optical fiber, it is also desirable that the UWB signals can be generated in the optical domain without having extra electrical-to-optical conversion. In addition, UWB signals that are generated in the optical domain can be easily tailored to have a spectrum that meets the FCC-specified spectral mask. In this paper, techniques to generate UWB signals in the optical domain will be discussed. These techniques are divided into three categories, with the generation of UWB signals based on the following: 1) phase-modulation-to-intensity-modulation conversion; 2) a photonic microwave delay-line filter; and 3) optical spectral shaping and dispersion-induced frequency-to-time mapping. The areas for future development and the challenge of implementation of these techniques for practical applications will also be discussed.

/pdf/photonic-generation-of-ultrawideband-signals-44jhndjzlw.pdf

Photonic Generation of Ultrawideband Signals

A novel ultra-wideband (UWB) bandpass filter (BPF) is presented using the hybrid microstrip and coplanar waveguide (CPW) structure. A CPW nonuniform resonator or multiple-mode resonator (MMR) is constructed to produce its first three resonant modes occurring around the lower end, center, and higher end of the UWB band. Then, a microstrip/CPW surface-to-surface coupled line is formed and modeled to allocate the enhanced coupling peak around the center of this UWB band, i.e., 6.85GHz. As such, a five-pole UWB BPF is built up and realized with the passband covering the entire UWB band (3.1-10.6GHz). A predicted frequency response is finally verified by the experiment. In addition, the designed UWB filter, with a single resonator, only occupies one full-wavelength in length or 16.9mm.

/pdf/ultra-wideband-bandpass-filter-with-hybrid-microstrip-cpw-5972ylwg50.pdf

Ultra-wideband bandpass filter with hybrid microstrip/CPW structure

A compact ultra-wideband (UWB) bandpass filter (BPF) with narrow notched (rejection) band in the UWB passband realized on a microstrip line is implemented and presented in this letter for use in wireless communication applications within the unlicensed UWB range set by the Federal Communications Commission (FCC). The filter consists of five short-circuited stubs separated by nonredundant connecting lines in order to exhibit a high selectivity filtering characteristic. The narrow notched (rejection) band was introduced by using a new technique which involves embedding open stubs in the first and last connecting lines in order to reject any undesired existing radio signal which may interfere with the determined UWB passband. The bandwidth of the notched filter can be controlled by adjusting the width of the stubs or the gaps or both. The length of the stubs can be tuned to select a specific frequency for the notched band. The embedded stubs can be used to excite single or double band-reject response. Two UWB BPFs with narrow notched band having a fractional bandwidth (FBW) of about 4.6% and 6.5% were realized theoretically and verified by full-wave EM simulation and the experiment. Excellent agreement between the predicted and measured results was obtained and is demonstrated

Ultra-Wideband (UWB) Bandpass Filter With Embedded Band Notch Structures

A compact microstrip-line ultra-wideband (UWB) bandpass filter (BPF) using the proposed stub-loaded multiple-mode resonator (MMR) is presented. This MMR is formed by loading three open-ended stubs in shunt to a simple stepped-impedance resonator in center and two symmetrical locations, respectively. By properly adjusting the lengths of these stubs, the first four resonant modes of this MMR can be evenly allocated within the 3.1-to-10.6 GHz UWB band while the fifth resonant frequency is raised above 15.0GHz. It results in the formulation of a novel UWB BPF with compact-size and widened upper-stopband by incorporating this MMR with two interdigital parallel-coupled feed lines. Simulated and measured results are found in good agreement with each other, showing improved UWB bandpass behaviors with the insertion loss lower than 0.8dB, return loss higher than 14.3dB, and maximum group delay variation less than 0.64ns in the realized UWB passband

Compact UWB Bandpass Filter Using Stub-Loaded Multiple-Mode Resonator

A novel microstrip-line ultra-wideband (UWB) bandpass filter is proposed and implemented using a multiple-mode resonator (MMR), aiming at transmitting the signals in the whole UWB passband of 3.1-10.6GHz. In the design, the first three resonant frequencies of this MMR are properly adjusted to be placed quasiequally within the UWB. Then, the parallel-coupled lines at the two sides are longitudinally stretched so as to raise the frequency-dispersive coupling degree with the coupling peak near the center of the UWB. After optimization of this filter, a good UWB bandpass behavior with five transmission poles is theoretically realized and experimentally confirmed. Within the whole UWB passband, the return loss is found higher than 10dB, and the group delay variation is less than 0.23ns.

/pdf/ultra-wideband-uwb-bandpass-filters-using-multiple-mode-26rag3cdca.pdf

Ultra-wideband (UWB) bandpass filters using multiple-mode resonator

Two types of suspended stripline ultra-wideband bandpass filters are described, one based on a standard lumped element (L-C) filter concept including transmission zeroes to improve the upper passband slope, and a second one consisting of the combination of a low-pass and a high-pass filter.

/pdf/low-loss-ultra-wideband-uwb-filters-using-suspended-45gn6ttrmg.pdf

Low-loss ultra-wideband (UWB) filters using suspended stripline

A novel microstrip-line ultra-wideband (UWB) band- pass filter is proposed and implemented using a multiple-mode res- onator (MMR), aiming at transmitting the signals in the whole UWB passband of 3.1-10.6 GHz. In the design, the first three res- onant frequencies of this MMR are properly adjusted to be placed quasiequally within the UWB. Then, the parallel-coupled lines at the two sides are longitudinally stretched so as to raise the fre- quency-dispersive coupling degree with the coupling peak near the center of the UWB. After optimization of this filter, a good UWB bandpass behavior with five transmission poles is theoretically re- alized and experimentally confirmed. Within the whole UWB pass- band, the return loss is found higher than 10 dB, and the group delay variation is less than 0.23 ns.

Ultra-Wideband (UWB) Bandpass Filters

This paper demonstrates a general concept and different types of filters and a diplexer realized in suspended stripline using quasi-lumped elements. Very small low-pass, bandpass, and high-pass filters with typically low loss are designed, fabricated, and tested; even transmission zeroes can easily be included into the design by additional coupling structures. Finally, a low-pass and high-pass filter are combined to form a diplexer of very small size.

/pdf/quasi-lumped-suspended-stripline-filters-and-diplexers-4utes34491.pdf

Quasi-lumped suspended stripline filters and diplexers

A quasi-planar reflector arrangement for generating an arbitrary phase and amplitude distribution in the antenna aperture and thus a wide range of far field patterns is presented. A parallel pair of reflectarrays is used. One is implemented as a standard reflectarray using rectangular patches on a microwave substrate with metallized backside. The other reflectarray is provided with a polarizing grid, which acts as a ground plane for one polarization and is transparent for the orthogonal polarization. An offset rectangular feed horn is embedded in the lower reflectarray to illuminate the upper reflector. A design procedure for a linear polarized antenna with a sector beam in the azimuth and a narrow beam width in the elevation is presented and is verified with measurement results.

/pdf/a-dual-planar-reflectarray-with-synthesized-phase-and-sk7ea28ggv.pdf

W. Menzel

Papers

Ultra-wideband (UWB) bandpass filters using multiple-mode resonator

Low-loss ultra-wideband (UWB) filters using suspended stripline

Ultra-Wideband (UWB) Bandpass Filters

Quasi-lumped suspended stripline filters and diplexers

A dual planar reflectarray with synthesized phase and amplitude distribution