Kamil Yavuz Kapusuz

Bio: Kamil Yavuz Kapusuz is an academic researcher from Ghent University. The author has contributed to research in topics: Antenna (radio) & Microstrip antenna. The author has an hindex of 7, co-authored 29 publications receiving 131 citations. Previous affiliations of Kamil Yavuz Kapusuz include Atılım University.

Entire Domain Basis Function Expansion of the Differential Surface Admittance for Efficient Broadband Characterization of Lossy Interconnects

Abstract: This article 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 with 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 the results with commerical software tools and with measurements.

Polarization Reconfigurable Air-Filled Substrate Integrated Waveguide Cavity-Backed Slot Antenna

Abstract: 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 substrate-integrated-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 TE11,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.

Low-profile scalable phased array antenna at Ku-band for mobile satellite communications

Abstract: This paper discusses the design of an 8×8 phased array antenna tile for Ku-band mobile satellite communications. The array has low-profile, high-gain, and wide-angle scanning properties. The design steps and electromagnetic analysis of a dual-polarized radiating antenna element and an 8×8 array tile comprised of these radiating elements are presented. The array structure makes it possible for satellite communication (SATCOM) terminals with compact sizes, because the whole front-end might be on the same multilayer printed circuit board (PCB). With a compact geometry and 25% bandwidth, the array promises an excellent performance for satellite communication applications. The radiation characteristics and other array parameters are evaluated with respect to the application requirements.

Partially Filled Half-Mode Substrate Integrated Waveguide Leaky-Wave Antenna for 24 GHz Automotive Radar

Abstract: 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 × 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, the main radiating direction steers continuously from 38 $^\circ$ to 58 $^\circ$ with an average half-power beamwidth of 12 $^\circ$ when the operating frequency changes from 22 to 26 GHz. In comparison, a 160 mm long dielectric-filled SIW (DFSIW) LWA yields a measured scanning range of 49 $^\circ$ 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 $^\circ$ 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.

Substrate-Independent Microwave Components in Substrate Integrated Waveguide Technology for High-Performance Smart Surfaces

Abstract: 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.

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

Abstract: 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.

A Millimeter-Wave Antenna System for Wideband 2-D Beam Steering

Abstract: This article presents a wideband beam-steering antenna system for high-mobility millimeter-wave (mm-wave) systems. It can provide both continuous and discrete beam steering in two dimensions (elevation and azimuth) at a speed that is sufficient for various applications including some in defense. The antenna is completely passive and beam steering is achieved using near-field phase transformation by employing a pair of distinct rotatable stepped-dielectric phase transformers (SPTs) placed in the near-field region of a fixed radiating source. The antenna system has a steering and impedance-matching bandwidth of 40.6% from 26.5 to 40 GHz. A prototype of the beam-steering antenna system including a mechanical system to rotate each of the SPTs around the antenna axis has been fabricated and tested. The rotating SPT pair introduces a predetermined phase gradient to the input near-field and creates an output near-field that will radiate in an arbitrarily selected direction, which can be varied within a large conical region with a maximum apex angle of 104°. The system exhibits predicted and measured peak gains of 21.5 and 21.25 dBi, respectively, and the measured gain variation over 2-D beam steering is less than 3 dB except at 36 and 39 GHz, where it rises to 3.6 and 3.1 dB, respectively. This beam steering method obviates the need for expensive phase shifters and distribution networks, which are also lossy at mm-wave frequencies. The measured results validate the predicted wideband matching and steering performance of the system with close agreement.

Compact Dual-Polarized Continuous Transverse Stub Array With 2-D Beam Scanning

Abstract: A dual-polarized (DP) flat antenna array with passive 2-D beam-scanning capability is presented in this paper. The array consists of a DP continuous transverse stub (CTS) array, a flat Risley prism (FRP), and a line source generator. Two sets of CTSs, being constituted by the substrate-integrated waveguide (SIW), share a common aperture and are arranged orthogonally for the DP operation. A novel compact long line source is proposed for exciting this DP-CTS array. The FRP is realized by two linear phase progression phase-shifting surfaces (LPP-PSSs) and is placed above the DP-CTS array. The beam-scanning capability in the azimuth and in the elevation can be realized by rotating simultaneously the two LPP-PSSs in the same and in the opposite directions, respectively. A six-element array prototype is simulated and fabricated. According to the measured results, beam-scanning ranges of 40° in the elevation and 360° in the azimuth are achieved with the maximum gain of 17.8 dBi. The novel contributions from this paper include: 1) a novel compact long line source and 2) the first passive DP 2-D beam-scanning flat antenna array. This array can be extended easily to a higher gain or a circular polarization application.