Dual-polarized 28-GHz air-filled SIW phased antenna array for next-generation cellular systems

A high-performance dual-polarized eight-element air-filled substrate-integrated-waveguide (AFSIW) cavity-backed patch antenna array is presented. The antenna operates in the [26.5-29.5] GHz band and provides a stable high data-rate wireless communication link between end-user terminals and access points in next-generation cellular systems. Its topology is carefully selected to maximize the performance of the array. In addition, by combining the AFSIW technology with a new antenna architecture, a low-profile, low-cost, stable, and high-performance array design is guaranteed. A prototype was fabricated and validated, demonstrating a wide active impedance bandwidth over ±35 o scanning range and low-cross polarization level within the entire frequency band

Determination of scattering center of multipath signals using geometric optics and Fresnel zone concepts

AbstractIn this study, a method for determining scattering center (or center of scattering points) of a multipath is proposed, provided that the direction of arrival of the multipath is known by the receiver. The method is based on classical electromagnetic wave principles in order to determine scattering center over irregular terrain. Geometrical optics (GO) along with Fresnel zone concept is employed, as the receiver, the transmitter positions and irregular terrain data are assumed to be provided. The proposed method could be used at UHF bands, especially, operations of radars and electronic warfare applications

Substrate-independent microwave components in substrate integrated waveguide technology for high-performance smart surfaces

Although all existing air-filled substrate integrated waveguide (AFSIW) topologies yield a 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 high-performance microwave components into a wide range of general-purpose commercially available surface materials by means of standard additive (3-D 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

Multipolarization-reconfigurable air-filled substrate integrated waveguide cavity-backed slot antenna

A novel single-feed ultrawideband cavity-backed slot antenna with a reconfigurable polarization capability is demonstrated in substrate-independent air-filled substrate integrated waveguide (AFSIW) technology for Internet-of-Things applications in the [5.15-5.85] GHz frequency band of the unlicensed national information infrastructure. The antenna achieves an ultrawide impedance bandwidth by exploiting a double ring of slots and supports four switchable linear polarization states (+/- 45 degrees, 0 degrees, +45 degrees, and 90 degrees) by leveraging four quartets of p-i-n diodes. By electrically shorting the slots at well-defined positions by these p-i-n diodes, dynamic polarization reconfiguration is achieved by switching their dc bias current, supplied at the antenna feed through an external bias tee and routed from the antenna's back to front cavity plane via the AFSIW sidewalls. This new simple, yet effective, bias network enables the integration of all polarization control electronics inside the antenna cavity to protect them from environmental effects. Finally, measurements prove that the prototype exhibits an overlapping impedance bandwidth of 29%, from 4.85 to 6.45 GHz, and a stable conically shaped radiation pattern across the operating bandwidth with a 3 dB beamwidth of 45 degrees and a peak gain of 6.5 dBi for all four states

An enhanced differential surface admittance operator for the signal integrity modeling of interconnects

A new, enhanced formulation of the 3-D differential surface admittance operator is presented in this contribution. By employing closed expressions for the sums of the infinite series that arise from discretizing the operator by means of entire domain basis functions, a more efficient and accurate form is obtained. Convergence analysis demonstrates the performance gain. Additionally, the appositeness of the novel operator is studied by analyzing results for various interconnect structures over a broad frequency range and by comparing with other research and commercial solvers

A dual-band polarization independent FSS having a transparent substrate for ISM and Wi-Fi shielding

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

Partially filled half-mode substrate integrated waveguide leaky-wave antenna for 24 GHz automotive radar

A novel highly efficient leaky-wave antenna (LWA), based on a periodic set of holes created in a half-mode substrate integrated waveguide (SIW), is conceived for automotive radar. The computer-aided design of this partially filled SIW (PFSIW) LWA is carried out using a full-wave electromagnetic simulator. As a proof-of-concept, an LWA prototype having a plate size of 15 x 126 mm(2) is fabricated through a standard low-cost printed circuit board (PCB) manufacturing process. Our manufactured prototype yields more than 25% impedance bandwidth, targeting the 24 GHz automotive short-range-radar band. Moreover, the measured peak gain and total antenna efficiency reach up to 15.5 dBi and 85% at 24 GHz. Furthermore, themain radiating direction steers continuously from 38 degrees to 58 degrees with an average half-power beamwidth of 12. when the operating frequency changes from 22 to 26 GHz. In comparison, a 160 mm long dielectric-filled SIW (DFSIW) LWA yields ameasured scanning range of 49 degrees and a total antenna efficiency of 43.8%, whereas an 80.3 mm long air-filled SIW (AFSIW) LWA exhibits a measured scanning range of 9 degrees and a total antenna efficiency of 80%. Therefore, PFSIW technology provides an optimal tradeoff between DFSIW and AFSIW for the envisaged short-range automotive radar application

Neural network based estimation of resonant frequency of an equilateral triangular microstrip patch antenna

U ovom se radu predlaže model umjetne neuronske mreže za procjenu rezonantnih frekvencija antena s istostraničnom trokutastom osnovom. Neuronska mreža primijenjena ovdje uvježbana je i testirana za jednoslojne kao i dvoslojne antene. Eksperiment je pokazao da su rezonantne frekvencije dobivene neuronskom mrežom za obadvije antene točnije od frekvencija izračunatih formulom i da su zadovoljavajuće blizu izmjerenim frekvencijama. Rezultati su obećavajući u odnosu na raspoloživu literaturu. Ovaj rad može također ponuditi učinkovitiji pristup za razvoj takvih antena. Dok je ukupna apsolutna greška od 7 MHz i prosječna greška od 0,09 % dobivena za jednoslojnu antenu; za dvoslojnu antenu je ukupna apsolutna greška 49 MHz, a prosječna greška 0,07 %.This study proposes an artificial neural network (ANN) model in order to approximate the resonant frequencies of equilateral triangular patch antennas. The neural network structure applied here is trained and tested for both single-layer and double-layer antennas. It is shown upon experiment that the resonant frequencies obtained from the neural network are both more accurate than the calculated frequencies by formula and satisfactorily close to the measured frequencies. Results appear to be promising as per the available literature. This paper also may offer more efficient approach to developing antennas of such nature. While the total absolute error of 7 MHz and the average error of 0,09 % are achieved for single-layer antenna, the total absolute and average errors are 49 MHz and 0,07 % for the double-layered antenna, respectively