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The design of a compact low-loss diplexer based on complementary microstrip spiral resonators is described. The resonant elements are two: one is low-pass (channel A) and the other is passband (channel B). The low-pass element is composed of spirals departing from a circle, whereas the passband element is composed of spirals etched on a circle. The former element is novel and has been extensively analyzed here. These elements are connected using a star nonresonant Y-junction to form a single-layer vialess diplexer. As an example, a diplexer working at 0.87 and 2.0 GHz for satellite communications is manufactured and tested. The measured data show an insertion loss equal to 0.58 dB (0.66 dB) for channel A (B). The return loss exceeds 15 dB for both channels, and the dimensions are 0.129 λ × 0.265 λ ≈ 0.0343 λ² . [ABSTRACT FROM AUTHOR]

The article describes a novel low‐loss microwave diplexer based on compact planar filtering elements. These are composed of spiral resonators and etched directly onto the signal layer. Furthermore, their design and optimization prove to be easy, and their native high‐pass/low‐pass characteristics are perfectly suited for assembling a diplexer. To verify the claim, a diplexer is designed and fabricated. It operates at 1.9 GHz and 3.5 GHz, and it is intended for personal communications service and 5G applications. The proposed device has an active area of 15.5 mm × $\times $ 19.5 mm. It shows an insertion loss of 0.35 dB and 0.28 dB for the two channels, representing the lowest data reported in the literature for this kind of device and technology. Additionally, the −10 dB‐fractional bandwidths for the lower and upper bandwidths are 40.6% and 20.2%, respectively, and isolation is at least 25 dB for both channels. [ABSTRACT FROM AUTHOR]

An improved and easy-to-implement HFSSMATLAB interface is presented. Because the interface is realized without the use of VBA scripts, it is easier to implement for beginners and practitioners. This advantage allows more dissemination of the code in the HFSS community. The interface is applied to the numerical design of a patch antenna, showing the capabilities it enables. Practical details about the implementation are provided, enabling the reader to implement the interface on their own. [ABSTRACT FROM AUTHOR]

Transformation optics is a powerful tool allowing remapping a generic domain into another yet maintaining a correspondence of the solution of Maxwell's equations within the two domains. Transformation optics has been used in the past to conveniently solve for modes in a generic waveguide by transforming its cross‐section into a circular one. Such a transformation needs particular care in enforcing boundary conditions in the transformed, circular, domain. In this paper, a theoretical treatment of boundary conditions is presented, allowing for an accurate computation of all field components in a generic waveguide. [ABSTRACT FROM AUTHOR]

This article applies a new method to analyze modes in empty waveguides having perfectly conducting walls and a rather generic cross‐section. The method is based on a coordinate transformation that maps the generic profile of the waveguide cross‐section to a circular waveguide (CW) filled with an anisotropic material. Modes in this latter waveguide can be represented as a series over the corresponding free‐space CW modes. This representation is particularly useful if used as a modal expansion over the port of a 2.5D or 3D device treated with a transformation optics approach. The method is particularly efficient when the waveguide is "similar" to a CW. Applications are shown to the analysis of some waveguides of arbitrary cross‐section with a view on practical applications. [ABSTRACT FROM AUTHOR]