Abstract-Although all existing air-filled substrate integrated waveguide (AFSIW) topologies yield substrate-independent electrical performance, they rely on dedicated, expensive, laminates to form air-filled regions that contain the electromagnetic fields. This paper proposes a novel substrate-independent AFSIW manufacturing technology, enabling straightforward integration of highperformance microwave components into a wide range of generalpurpose commercially-available surface materials by means of standard additive (3D printing) or subtractive (computer numerically controlled milling/laser cutting) manufacturing processes. First, an analytical formula is derived for the effective permittivity and loss tangent of the AFSIW waveguide. This allows the designer to reduce substrate losses to levels typically encountered in high-frequency laminates. Then, several microwave components are designed and fabricated. Measurements of multiple AFSIW waveguides and a four-way power divider/combiner, both relying on a new coaxial-to-air-filled SIW transition, prove that this novel approach yields microwave components suitable for direct integration into everyday surfaces, with low insertion loss, and excellent matching and isolation over the entire [5.15 − 5.85] GHz band. Hence, this innovative approach paves the way for a new generation of cost-effective, high-performance and invisibly-integrated smart surface systems that efficiently exploit the area and the materials available in everyday objects.
This paper presents a dual-band, polarization independent FSS for ISM and Wi-Fi shielding. The proposed structure has a band-stop characteristic for 2.5 and 5.1 GHz with a fractional bandwidth of 42% and 7%, respectively. The substrate of the FSS is a transparent material having a permittivity value of 2.77 and a thickness value of 1.48 mm, which provides band-pass characteristics for visible spectrum. The design, fabrication, and measurement of FSS were conducted for TM and TE polarizations; and satisfactory agreement was obtained
This paper presents a full-wave method to characterize lossy conductors in an interconnect setting. To this end, a novel and accurate differential surface admittance operator for cuboids based on entire domain basis functions is formulated. By combining this new operator with the augmented electric field integral equation, a comprehensive broadband characterization is obtained. Compared to the state-of-the-art in differential surface admittance operator modeling, we prove the accuracy and improved speed of the novel formulation. Additional examples support these conclusions by comparing results with a commercial software tool and with measurements.
A multilayer ultra-wideband frequency selective surface (FSS), which filters the frequency range between 3.38 and 4.66GHz is presented. The proposed structure having a transparent substrate allows the light pass through itself, while it filters the electromagnetic waves at the frequency band of interest; and it has a bandwidth of 1.28 GHz. For the FSS structure, a transparency level of 52.5% obtained with a fractional bandwidth value of 32%. The structure is examined layer by layer; and the proposed FSS structures are evaluated in terms of bandwidth and transparency level
The Internet of Things requires highly efficient ultra-wideband antenna systems that yield high performance at low manufacturing cost. Therefore, a novel ultra-wideband circular air-filled substrateintegrated-waveguide (AFSIW) cavity-backed annular slot antenna is proposed that enables straightforward integration into general-purpose materials by means of standard manufacturing techniques. The cavity top plane, serving as antenna aperture, contains two concentric annular slots, both split into two by shorting tabs that create a virtual electric wall. This enables the generation of a TE 11,slot even mode in both parts of each annular slot, giving rise to a conical radiation pattern. By exciting two such modes and judiciously positioning their resonance frequencies, all the unlicensed national information infrastructure (U-NII) [5.15-5.85] GHz radio bands are covered. The annular slot antenna is then made polarization reconfigurable through an innovative excitation of the slot modes by replacing the shorting tabs with four pairs of the PIN diodes. These dynamically switch between two orthogonal linear polarizations by changing the dc control current at the antenna RF port through an external bias tee. This simple, yet effective, bias network enables the integration of all polarization control electronics inside the antenna cavity to protect them from environmental effects. A low-cost antenna substrate was realized through standard additive manufacturing in a 3D-printed substrate, while a standard high-frequency laminate was used to implement the upper conducting plane containing the radiating elements and the polarization reconfiguration electronics. The antenna features an impedance bandwidth of 0.93 GHz, a front-to-back ratio of 14 dB, a total antenna efficiency higher than 95%, and 4.9 dBi gain for each polarization state.INDEX TERMS Additive manufacturing, air-filled substrate-integrated-waveguide (AFSIW), cavity-backed slot antenna, circular cavity, in-cavity electronics, PIN diode, partially-filled circular waveguide, polarization reconfiguration, reconfigurable antenna, substrate-independent, ultra-wideband.
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