Perfect Magnetic Conductor Surface Research Articles

Ka-Band Diplexer for 5G mmWave Applications in Inverted Microstrip Gap Waveguide Technology

A new cost-efficient, low-loss Ka-band diplexer designed in inverted microstrip gap waveguide technology is presented in this paper. Gap waveguide allows to propagate quasi-TEM modes in the air between two metal plates without the need for contact between them by using periodic metasurfaces. The diplexer is realized by using a bed of nails as AMC (Artificial Magnetic Conductor), first modeled with a PMC (Perfect Magnetic Conductor) surface for design simplification, and two fifth order end-coupled passband filters (BPFs) along with a power divider. The experimental verification confirms that the two channels centered at 24 GHz and 28 GHz with 1 GHz of bandwidth show measured insertion losses of 1.5 dB and 2 dB and 60 dB of isolation between them. A slight shift in frequency is observed in the measurements that can be easily explained by the variation in the permittivity of the substrate.

Efficient Analytical Prediction of the Cavity Resonant Behavior of PEC–PMC Metallic Enclosures and Packages

A metal enclosure whose lid is covered by an array of metal pins is studied in this article. The pins are able to realize a fictitious perfect magnetic conductor surface at the pin end, thus inhibiting cavity resonances in a well-defined frequency band. The article proposes an analytical model for predicting the behavior of the cavity, and thus for estimating the bandgap limits. The method is based on the planar cavity formulation and it embeds analytically the pin to bottom plate capacitance. The obtained cavity response agrees well with the simulated models of various cavity and pins dimensions. Moreover, the method is validated experimentally based on manufactured cavities. An in-depth parametric analysis is carried out for precisely evaluating the limit of validity of the proposed cavity model based approach in the prediction of the bandgap upper and lower limits.

Millimeter-Wave Dual-Mode Filters Realized in Microstrip-Ridge Gap Waveguide Technology

In this paper, we propose novel microstrip-ridge gap waveguide (MS-RGW) millimeter-wave bandpass filters based on a dual-mode resonator. The resonator represents a rectangular patch grounded by a set of vias, whose pair of fundamental degenerate modes are separated in the spectrum using the via position perturbation. MS-RGW feeding lines are realized as periodically grounded microstrip lines inserted into a perfect magnetic conductor (PMC) structure, which are fed via the 2.92-mm connector through the specifically designed transition. A detailed analysis of the filters is provided together with the analysis of their building blocks—mushroom-based PMC surface, MS-RGW with periodically grounded microstrip line, and dual-mode resonator. The proposed filters are fabricated using standard PCB technology and the measured results show that the filters exhibit low losses, good in-band and out-of-band characteristics, and good selectivity. As such, the proposed filters represent excellent candidates for millimeter-wave filtering applications since they reconcile the requirements for high performance, low loss, and low cost.

Modeling and Design Empirical Formulas of Microstrip Ridge Gap Waveguide

Recently, interest in the microstrip ridge gap waveguide (MRGW) has increased due to the need for a self-packaged and low-loss structures for millimeter-wave applications. The MRGW consists of a grounded textured surface, which is artificially representing a perfect magnetic conductor surface loaded with a thin low dielectric constant substrate with a printed strip. This is topped with another dielectric substrate covered with a conducting plate at the top as a ground plane. Currently, the full-wave and optimization tools are used to design the MRGW structure. Consequently, an efficient modeling and design tool for the MRGW is proposed in this paper via curve fitting. Closed form empirical expressions for the effective dielectric constant, characteristic impedance, and the dispersion effect are provided. The developed expressions are generalized for arbitrarily chosen MRGW parameters. The expressions are verified with the full-wave solution. The results show the potential of the proposed approach in modeling the MRGW structure

Novel Low-Loss Millimeter-Wave Transition From Waveguide-to-Microstrip Line Suitable for MMIC Integration and Packaging

This letter presents a unique low-loss transition from microstrip to full height rectangular waveguide at W-band. This microstrip transition can be made as a part of the mm-wave monolithic microwave integrated circuit (MMIC) of arbitrary size, and thus, avoid the use of bond wires at the high-frequency port of the MMIC circuit. As a result, the MMIC can be coupled directly to the waveguide. The working principle of the transition is based on electromagnetic coupling, where the coupling between the microstrip mode and the TE10 waveguide mode is achieved via a resonant cavity. A perfect magnetic conductor (PMC) surface is placed over the cavity to facilitate the smooth coupling of electromagnetic energy from the microstrip line to the cavity and then from the cavity to the waveguide. The PMC surface also suppresses the unwanted waveguide mode coupling to the oversized MMIC substrate. The measured back-to-back transition works over the frequency band of 80-114 GHz (relative BW of 35%) with minimum return loss of 13.5 dB. The total insertion loss of the manufactured prototype is found to be varying from 0.54 to 0.803 dB, which implies a single transition loss of less than 0.27-0.4015 dB in W-band.

Notice of Retraction: Efficient Analytical Prediction of the EMI Bandgap Limits of PEC-PMC Metallic Enclosures Hosting RF and Digital Circuits

A metal enclosure whose lid is covered by an array of metal pins is studied in this paper. The pins are able to realize a fictitious perfect magnetic conductor surface at the pin end, thus inhibiting cavity resonances and propagation of electromagnetic interferences in a well-defined frequency band. This paper proposes an analytical model for predicting the behavior of the cavity, and thus for estimating the bandgap limits. The method is based on the planar cavity formulation, and it analytically embeds the pin-to-bottom-wall capacitance. The obtained cavity response agrees well with the simulated models of various cavity and pin dimensions. Moreover, the method is validated experimentally based on a manufactured cavity. Although some residual errors due to the difficulties in a precise calibration are present, the experimental results validate the proposed analytical model.

An equivalent realization of coherent perfect absorption under single beam illumination.

We have experimentally and numerically demonstrated that the coherent perfect absorption (CPA) can equivalently be accomplished under single beam illumination. Instead of using the counter-propagating coherent dual beams, we introduce a perfect magnetic conductor (PMC) surface as a mirror boundary to the CPA configuration. Such a PMC surface can practically be embodied, utilizing high impedance surfaces, i.e., mushroom structures. By covering them with an ultrathin conductive film of sheet resistance 377 Ω, the perfect (100%) microwave absorption is achieved when the film is illuminated by a single beam from one side. Employing the PMC boundary reduces the coherence requirement in the original CPA setup, though the present implementation is limited to the single frequency or narrow band operation. Our work proposes an equivalent way to realize the CPA under the single beam illumination, and might have applications in engineering absorbent materials.

A corrugated perfect magnetic conductor surface supporting spoof surface magnon polaritons.

In this paper, we demonstrate that spoof surface magnon polaritons (SSMPs) can propagate along a corrugated perfect magnetic conductor (PMC) surface. From duality theorem, the existence of surface electromagnetic modes on corrugated PMC surfaces are manifest to be transverse electric (TE) mode compared with the transverse magnetic (TM) mode of spoof surface plasmon plaritons (SSPPs) excited on corrugated perfect electric conductor surfaces. Theoretical deduction through modal expansion method and simulation results clearly verify that SSMPs share the same dispersion relationship with the SSPPs. It is worth noting that this metamaterial will have more similar properties and potential applications as the SSPPs in large number of areas.

Design of Optimized Multilayer PIFA With the EBG Structure for SAR Reduction in Mobile Applications

This paper proposes an optimized multilayer planar inverted-F antenna (PIFA) with an electromagnetic bandgap (EBG) at personal communication services band for specific absorption rate (SAR) reduction. The EBG structure, which has bandgap capability and acts as a perfect magnetic conductor surface, can suppress surface waves and reduce undesired radiation from an antenna. Thus, the EBG structure is capable of preventing electromagnetic (EM) fields being emitted in the direction of the human head. To optimize the multilayer PIFA structure for SAR reduction, the EBG structure between the printed circuit board and antenna layer is designed first. Second, a parameter study about the EBG cell numbers, height, and location of the PIFA with the EBG structure is performed. Finally, the optimized multilayer PIFA with the EBG is investigated and the S-parameters, radiation patterns, total radiated power values, and SAR values are presented. The results demonstrate the reduction of SAR values while maintaining the antenna performance. Thus, the human head can be protected from hazardous EM fields using the EBG structure.

A novel MEMS-based CPW-fed slot antenna for broadband circular polarization and unidirectional radiation

A novel CPW-fed millimeter wave slot antenna for broadband circular polarization and unidirectional radiation with multilayer 3D structures is discussed. The antenna is fabricated based on micro-electro-mechanical systems micro-fabrication technology. Through a special short-circuiting stub perturbation method, the circular ring slot antenna generates circularly polarized radiation and achieves a broad impedance bandwidth of 20% with voltage standing-wave ratio (VSWR) ⩽ 2 and circularly polarized bandwidth of 17.6% with AR ⩽ 3 dB. By adding a special wave guiding slot structure and wave cutoff slot structure, a novel approximate perfect magnetic conductor surface, the antenna radiates unidirectionally and the peak gain increases from about 5.2 dB to 7.5 dB.

Limitation on the bandwidth of artificial perfect magnetic conductor surfaces

A perfect magnetic conductor surface reflects electromagnetic waves without phase change of the electric field, in contrast to the 180° phase change from a perfect electric conductor. Existing structures achieve this condition only at a particular frequency. The phase variation away from this frequency is larger for thinner structures, leading to smaller bandwidth over which the desired condition is achieved to given tolerance. There is fundamental upper limit on the bandwidth of structures based on frequency-selective surfaces arising from the causality and passivity of the structure.