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

This article presents a novel dual-polarized millimeter-wave (mm-Wave) patch antenna with bandpass filtering response. The proposed antenna consists of a differential-fed cross-shaped driven patch and four stacked parasitic patches. The combination of the stacked patches and the driven patch can be equivalent to a bandstop filtering circuit for generating a radiation null at the upper band edge. Besides, four additional shorted patches are added beside the cross-shaped driven patch to introduce another radiation null at the lower band edge. Moreover, by embedding a cross-shaped strip between these four stacked patches, the third radiation null is generated to further suppress the upper stopband. As a result, a quasi-elliptic bandpass response is realized without requiring extra filtering circuit. For demonstration, a prototype was fabricated with standard PCB process and measured. The prototype operates in the 5G band (24.25–29.5 GHz) and it has an impedance bandwidth of 20%. The out-of-band gain drops over 15 dB at 23 and 32.5 GHz, respectively, which exhibits high selectivity. These merits make the proposed antenna a good element candidate for the 5G mm-Wave massive MIMO applications to reduce the requirements of the filters in the mm-Wave RF front ends.

Millimeter-Wave Dual-Polarized Filtering Antenna for 5G Application

A structure of a compact ultra-wideband monopole antenna has been presented. The antenna consists of a microstrip-fed rectangle radiator as well as a ground plane with a rectangle slit and an L-shaped stub. The critical factor in achieving a small size is a careful design procedure involving numerical optimisation of all geometry parameters of the antenna aiming at explicit size reduction while maintaining acceptable electrical performance. The final design exhibits dimensions of only 9.45 × 18.5 mm and a footprint of 175 mm
 2
. Experimental validation and comparisons with competitive designs are also provided.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/el.2015.4432

Compact UWB monopole antenna for internet of things applications

Multi-beam antennas are critical components in future terrestrial and non-terrestrial wireless communications networks. The multiple beams produced by these antennas will enable dynamic interconnection of various terrestrial, airborne and space-borne network nodes. As the operating frequency increases to the high millimeter wave (mmWave) and terahertz (THz) bands for beyond 5G (B5G) and sixth-generation (6G) systems, quasi-optical techniques are expected to become dominant in the design of high gain multi-beam antennas. This paper presents a timely overview of the mainstream quasi-optical techniques employed in current and future multi-beam antennas. Their operating principles and design techniques along with those of various quasi-optical beamformers are presented. These include both conventional and advanced lens and reflector based configurations to realize high gain multiple beams at low cost and in small form factors. New research challenges and industry trends in the field, such as planar lenses based on transformation optics and metasurface-based transmitarrays, are discussed to foster further innovations in the microwave and antenna research community.

/pdf/quasi-optical-multi-beam-antenna-technologies-for-b5g-and-6g-1gpf5orbnv.pdf

Quasi-Optical Multi-Beam Antenna Technologies for B5G and 6G mmWave and THz Networks: A Review

A compact wideband four-way filtering PD is presented. The structure of the proposed device includes a pair of looped coupled-line structures to provide the needed power division to four output ports. Moreover, a pair of short-ended coupled-line stubs is used to introduce multiple transmission poles and transmission zeros for a sharp cut-off of the passband and high upper-stopband rejection. A detailed design procedure is shown to determine the initial design parameters. A prototype is designed, simulated and measured experimentally. The measured results show 56.5% bandwidth centered at 1.5 GHz with more than 15 dB upper-stopband rejection up to 4.15 GHz, more than 13 dB in-band isolation, and 15 dB return loss at all output ports.

Wideband Four-Way Filtering Power Divider With Sharp Selectivity and Wide Stopband Using Looped Coupled-Line Structures

A wideband tunable phase shifter that uses the concept of reflection-type phase shifter is proposed. The device is based on a tunable high-directivity directional coupler. The coupler uses two pairs of interconnected coupled-lines with suitable coplanar-waveguide transmission lines embedded within the ground plane. The tuning is realized by using two varactors and two inductors connected to two terminals of the coupler. Full-wave simulation is performed using co-simulation within ADS momentum using accurate SPICE model of the tuning elements. Moreover, a prototype is fabricated and tested. The tested results reveal that the proposed design can achieve wide operating bandwidth (105% fractional bandwidth) with 40° tuning phase.

Wideband tunable reflection-type phase shifter using high-directivity directional coupler

A 2-D Butler matrix (BM) in uniplanar configuration for designing multibeam array antenna (MAA) is proposed using substrate integrated waveguide (SIW) technology. Firstly, a novel topology for building uniplanar 2D BM is proposed, which successfully transforms the traditional 3-D topology to a 2-D (or uniplanar) one. To realize the planarization of basic components, a novel design of eight-port hybrid couplers, is developed to transform four spatially intersected couplers to a planar structure. To address the issue of excessive path intersections, a novel SIW eight-port crossover is proposed to reduce the number of path intersections from 16 to merely 4. Using this proposed 2-D BM, a 2-D MAA with 16 (4 × 4) beams can be realized.

Uniplanar 2-D Butler Matrix for Multibeam Arrays

An ultra-wideband (UWB) bandpass filter with a notch-band and wide upper stopband is presented in this paper. The UWB filter is realized using a ring resonator which is loaded with two sets of stubs, i.e. one is loaded in the center and two little stubs at the symmetrical side locations. The loaded stubs are used to create transmission zeros in upper stopband thus high modes are suppressed greatly. Moreover, two identical meandered resonators are inserted within the stub-loaded ring resonator, creating a notch-band around 5.8 GHz. Finally, two UWB filters with and without notch-band are simulated, fabricated, and measured results provide an experimental validation of predicted performance of the filter.

Ultra-wideband (UWB) bandpass filter based on stub-loaded ring resonator

This paper presents based on flexible coupling schemes using multiple quarter-wavelength resonators. Microstrip-to-slotline transitions were are used to provide external coupling to the filters. A dual-mode and tri-mode filter are designed. For the dual-mode design, a pair of quarter-wavelength resonators is used with a gap between them providing a suitable coupling coefficient. For the tri-band design, an additional resonator is coupled to the previous quarter-wavelength resonators, leading to a three-pole response within the passband. A microstrip line with a grounded resistor is added at the middle point of two output ports, leading to excellent output matching and isolation between output ports. Two design examples with dual-mode and tri-mode responses are realized with the verification using full-wave simulations.

Design of Out-of-phase Filtering Power Dividers Using Flexible Coupling Schemes

A compact quadruple-mode ultra-wideband (UWB) bandpass filter with sharp selectivity and extremely wide upper stopband is proposed in this paper, using a multi-stage stepped-impedance resonator, two open-circuited ends and a pair of high-low impedance stubs. The characteristics of the proposed multimode resonator are analyzed by simulation, demonstrating that the first four resonant modes can be appropriately located in the desired passband and other resonant modes in the upper stopband can be suppressed. To improve the skirt selectivity and out-of-band performance, two identical high-low impedance stubs are introduced into the design, without changing any resonant characteristic of the filter. Finally, the improved filter is fabricated and measured, and simulated and measured results are in good agreement to show that the proposed filter has a sharp selectivity with a −21.5 dB rejection stopband extended to over 30 GHz.

He Zhu

Papers

Wideband tunable reflection-type phase shifter using high-directivity directional coupler

Uniplanar 2-D Butler Matrix for Multibeam Arrays

Ultra-wideband (UWB) bandpass filter based on stub-loaded ring resonator

Design of Out-of-phase Filtering Power Dividers Using Flexible Coupling Schemes

Ultra-wideband (UWB) bandpass filter with sharp selectivity and wide upper stopband