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.

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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

Dual-band bandpass filters using novel stub-loaded resonators (SLRs) are presented in this letter. Characterized by both theoretical analysis and full-wave simulation, the proposed SLR is found to have the advantage that the even-mode resonant frequencies can be flexibly controlled whereas the odd-mode resonant frequencies are fixed. Based on the proposed SLR, a dual-band filter is implemented with three transmission zeros. To further improve the selectivity, a filter with four transmission zeros on either side of both passbands is designed by introducing spur-line. The measured results validate the proposed design.

Dual-Band Bandpass Filters Using Stub-Loaded Resonators

A single-fed miniaturized circularly polarized microstrip patch antenna is designed and experimentally demonstrated for industrial-scientific-medical (2.4-2.48 GHz) biomedical applications. The proposed antenna is designed by utilizing the capacitive loading on the radiator. Compared with the initial topology of the proposed antenna, the so-called square patch antenna with a center-square slot, the proposed method has the advantage of good size reduction and good polarization purity. The footprint of the proposed antenna is 10×10×1.27 mm3. The simulated impedance, axial ratio, and radiation pattern are studied and compared in two simulation models: cubic skin phantom and Gustav voxel human body. The effect of different body phantoms is discussed to evaluate the sensitivity of the proposed antenna. The effect of coaxial cable is also discussed. Two typical approaches to address the biocompatibility issue for practical applications are reported as well. The simulated and measured impedance bandwidths in cubic skin phantom are 7.7% and 10.2%, respectively. The performance of the communication link between the implanted CP antenna and the external antenna is also presented.

Capacitively Loaded Circularly Polarized Implantable Patch Antenna for ISM Band Biomedical Applications

A novel dual-band bandpass filter with meander-loop resonator and complement split-ring resonator (CSRR) defected ground structure (DGS) is proposed in this letter. Microstrip meanderloop resonator and CSRR DGS are operated for respective passbands. Several finite attenuation poles in stopbands are realized to improve the selectivity of the proposed bandpass filter and isolation between the two passbands. Compact size, dual band and high selectivity characteristics are realized by this type of filter structure. The filter is evaluated by experiment and simulation with very good agreement.

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Design of Novel Dual-Band Bandpass Filter with Microstrip Meander-Loop Resonator and CSRR DGS

This paper presents a novel approach for designing dual-mode dual-band bandpass filters with independently controlled center frequencies and bandwidths. Two microstrip perturbed ring resonators are employed to obtain dual-mode dual-band responses. Novel feeding structures are introduced to simultaneously feed the ring resonators and conveniently control the coupling strength between resonators and feeding lines, resulting in a wide tunable range of external quality factors. Two kinds of filter configurations with compact size are proposed. Both of them provide sufficient degrees of freedom to satisfy various requirements of external qualify factors and coupling coefficients at both passbands. Therefore, the center frequencies and fractional bandwidths of both passbands can be independently tuned to desired specifications within a wide range. To verify the proposed method, four filters are implemented. The measured results exhibit dual-mode dual-band bandpass responses with high selectivity.

Novel Dual-Mode Dual-Band Filters Using Coplanar-Waveguide-Fed Ring Resonators

An effective design of a reconfigurable patch antenna, with a wide operational bandwidth for wireless communication and radar systems, is presented in this paper. The reconfigurable patch possesses an E-shaped structure and its operation frequency can be changed by integrated switches. The operational frequency of the antenna can cover an octave frequency range by utilising only two switch states. In state 1, the antenna operates from 9.2 GHz to 15.0 GHz and, in state 2, from 7.5 GHz to 10.7 GHz. Relative bandwidths of 48% and 35% are obtained in the two states, respectively

Reconfigurable patch-antenna design for wideband wireless communication systems

A highly selective dual-band stepped impedance bandpass filter is presented. The filter has two tunable passbands. Two finite out-of-band transmission zeros are realised, which have high selectivity.

High-selectivity dual-band stepped-impedance bandpass filter

A compact slow-wave microstrip rat-race ring coupler is presented. The new structure effectively reduces the occupied area to 8% of the conventional rat-race ring coupler due to the slow-wave effect. The design is validated both by using the full-wave electromagnetic simulator and by measurement.

Compact slow-wave microstrip rat-race ring coupler

The authors investigate in this study using PIN attenuator diodes to reduce the radar cross-section (RCS) of a microstrip patch antenna. A simple design guideline and a useful loading scheme are developed. In the investigation, PIN diodes are equivalent to capacitances and resistances when diodes are reverse-biased and forward-biased, respectively. According to the magnitude distribution of the induced electric field under the patch for a specific incidence angle, the loading positions of PIN diodes are selected near to where the maximum electric field appears. First, three typical incident angles are separately considered. As a result, RCS reduction for the microstrip patch antenna is realised by utilising the variable resistance characteristic (energy dissipation) of PIN attenuator diodes. Secondly, the loading positions for that three incident angles are combined to realise RCS reduction over a large angular spatial region and within a wideband frequency range, and thus an electronically controllable low RCS status can be successfully realised. The proposed design guideline is demonstrated. It is worth mentioning that, by real-time adjusting the bias status of each PIN diode, the antenna realised gain as well as the relative bandwidth is well maintained when the antenna is at work.

Radar cross-section reduction for a microstrip patch antenna using PIN diodes

A novel pattern reconfigurable patch antenna with a microstrip configuration is proposed. The antenna consists of a disc patch, a ring and eight radially symmetrically distributed microstrip monopoles. The patterns are reconfigured by shifting the states of the eight switches and eight reconfigurable states are available. Each conical pattern around the broadside of the antenna has a wide beam width in the azimuth plane and the eight reconfigurable patterns can cover continuously the space in the horizontal plane. The performance is very advantageous for smart antenna applications on future mobile terminals.

S. Xiao

Papers

Reconfigurable patch-antenna design for wideband wireless communication systems

High-selectivity dual-band stepped-impedance bandpass filter

Compact slow-wave microstrip rat-race ring coupler

Radar cross-section reduction for a microstrip patch antenna using PIN diodes

Pattern reconfigurable antenna with wide angle coverage