Design and experimental verification of ridge gap waveguide in bed of nails for parallel-plate mode suppression

This study describes the design and experimental verification of the ridge gap waveguide, appearing in the gap between parallel metal plates. One of the plates has a texture in the form of a wave-guiding metal ridge surrounded by metal posts. The latter posts, referred to as a pin surface or bed of nails, are designed to give a stopband for the normal parallel-plate modes between 10 and 23 GHz. The hardware demonstrator includes two 90° bends and two capacitive coupled coaxial transitions enabling measurements with a vector network analyser (VNA). The measured results verify the large bandwidth and low losses of the quasi-transverse electromagnetic (TEM) mode propagating along the guiding ridge, and that 90° bends can be designed in the same way as for microstrip lines. The demonstrator is designed for use around 15 GHz. Still, the ridge gap waveguide is more advantageous for frequencies above 30 GHz, because it can be realised entirely from metal using milling or moulding, and there are no requirements for conducting joints between the two plates that otherwise is a problem when realising conventional hollow waveguides. © 2011 The Institution of Engineering and Technology.Kildal, P.; Zaman, AU.; Rajo Iglesias, E.; Alfonso Alós, E.; Valero-Nogueira, A. (2011). Design and experimental verification of ridge gap waveguide in bed of nails for parallel-plate mode suppression. IET Microwaves Antennas and Propagation. 5(3):262-270. doi:10.1049/iet-map.2010.0089S26227053Kildal, P.-S., Alfonso, E., Valero-Nogueira, A., & Rajo-Iglesias, E. (2009). Local Metamaterial-Based Waveguides in Gaps Between Parallel Metal Plates. IEEE Antennas and Wireless Propagation Letters, 8, 84-87. doi:10.1109/lawp.2008.2011147Kildal, P.-S.: ‘Waveguides and transmission lines in gaps between parallel conducting surfaces’, (European Patent Application EP08159791.6)7 July 2008Rajo-Iglesias, E., Zaman, A. U., & Kildal, P.-S. (2010). Parallel Plate Cavity Mode Suppression in Microstrip Circuit Packages Using a Lid of Nails. IEEE Microwave and Wireless Components Letters, 20(1), 31-33. doi:10.1109/lmwc.2009.2035960Kildal, P.-S. (1990). Artificially soft and hard surfaces in electromagnetics. IEEE Transactions on Antennas and Propagation, 38(10), 1537-1544. doi:10.1109/8.59765Valero-Nogueira, A., Alfonso, E., Herranz, J. I., & Kildal, P.-S. (2009). Experimental Demonstration of Local Quasi-TEM Gap Modes in Single-Hard-Wall Waveguides. IEEE Microwave and Wireless Components Letters, 19(9), 536-538. doi:10.1109/lmwc.2009.2027051Lier, E. (1990). Analysis of soft and hard strip-loaded horns using a circular cylindrical model. IEEE Transactions on Antennas and Propagation, 38(6), 783-793. doi:10.1109/8.55573Sievenpiper, D., Lijun Zhang, Broas, R. F. J., Alexopolous, N. G., & Yablonovitch, E. (1999). High-impedance electromagnetic surfaces with a forbidden frequency band. IEEE Transactions on Microwave Theory and Techniques, 47(11), 2059-2074. doi:10.1109/22.798001Silveirinha, M. G., Fernandes, C. A., & Costa, J. R. (2008). Electromagnetic Characterization of Textured Surfaces Formed by Metallic Pins. IEEE Transactions on Antennas and Propagation, 56(2), 405-415. doi:10.1109/tap.2007.915442Lindell, I. V. (2000). Ideal boundary and generalised soft and hard conditions. IEE Proceedings - Microwaves, Antennas and Propagation, 147(6), 495. doi:10.1049/ip-map:20000827Valero-Nogueira, A., Alfonso, E., Herranz, J. I., & Baquero, M. (2007). Planar slot-array antenna fed by an oversized quasi-TEM waveguide. Microwave and Optical Technology Letters, 49(8), 1875-1877. doi:10.1002/mop.22586Šipuš, Z., Merkel, H., & Kildal, P.-S. (1997). Green’s functions for planar soft and hard surfaces derived by asymptotic boundary conditions. IEE Proceedings - Microwaves, Antennas and Propagation, 144(5), 321. doi:10.1049/ip-map:19971335CST Microwave Studio 2008. Available at: www.cst.comKehn, M. N. M., & Kildal, P.-S. (2005). Miniaturized rectangular hard waveguides for use in multifrequency phased arrays. IEEE Transactions on Antennas and Propagation, 53(1), 100-109. doi:10.1109/tap.2004.840519Malcolm Ng Mou Kehn, M. N. M., Nannetti, Cucini, Maci, & Kildal. (2006). Analysis of dispersion in dipole-FSS loaded hard rectangular waveguide. IEEE Transactions on Antennas and Propagation, 54(12), 2275-2282. doi:10.1109/tap.2006.879198Grbic, A., & Eleftheriades, G. V. (2003). Periodic analysis of a 2-D negative refractive index transmission line structure. IEEE Transactions on Antennas and Propagation, 51(10), 2604-2611. doi:10.1109/tap.2003.817543Eleftheriades, G.V., and Balmain, K.G.: ‘Metamaterials for controlling and guiding electromagnetic radiation’, (US Patent 6859114 – Filed 2 June 2003)McKinzie, W.F.: ‘Circuit and method for suppression of electromagnetic coupling and switching noise in multilayer printed circuit boards’, (US Patent No. 7,215,007 B2)Schellenberg, J. M. (1995). CAD models for suspended and inverted microstrip. IEEE Transactions on Microwave Theory and Techniques, 43(6), 1247-1252. doi:10.1109/22.390179Anderson, T. N. (1956). Rectangular and Ridge Waveguide. IEEE Transactions on Microwave Theory and Techniques, 4(4), 201-209. doi:10.1109/tmtt.1956.1125063Pozar, D.: ‘Microwave engineering’, 3rd(Wiley 2005), p. 139Bosiljevac, M., Sipus, Z., & Kildal, P.-S. (2010). Construction of Green’s functions of parallel plates with periodic texture with application to gap waveguides – a plane-wave spectral-domain approach. IET Microwaves, Antennas & Propagation, 4(11), 1799. doi:10.1049/iet-map.2009.0399Zaman, A. U., Rajo-Iglesias, E., Alfonso, E., & Kildal, P.-S. (2009). Design of transition from coaxial line to ridge gap waveguide. 2009 IEEE Antennas and Propagation Society International Symposium. doi:10.1109/aps.2009.5172186Sharp, E. D. (1963). A High-Power Wide-Band Waffle-Iron Filter. IEEE Transactions on Microwave Theory and Techniques, 11(2), 111-116. doi:10.1109/tmtt.1963.1125611KIRINO, H., OGAWA, K., & OHNO, T. (2008). A Variable Phase Shifter Using a Movable Waffle Iron Metal Plate and Its Applications to Phased Array Antennas. IEICE Transactions on Communications, E91-B(6), 1773-1782. doi:10.1093/ietcom/e91-b.6.177

Numerical Prepackaging with PMC Lid - Efficient and Simple Design Procedure for Microstrip Circuits Including the Packaging

The paper presents an efficient method for the design of printed microstrip circuit with packaging in mind, referred to as numerical prepackaging with a perfectly magnetic conductive (PMC) lid. The method comprises making the design including the packaging from the start by using a PMC lid, rather than first designing the open-aired circuit; and thereafter, considering the packaging effect and the often required retuning of the circuits themselves. The advantage is that no parallel plate modes can propagate between the perfect electric conductor (PEC) ground plane and the PMC lid plate if the spacing is smaller than an effective quarter of wavelength. This provides a limited computational volume so that the computation time is significantly reduced in the case of the finite element method (FEM) or the finite difference time domain method (FDTD). By using numerical packaging with PMC lid, the ideal PMC lid has to be realized afterwards e.g. by using a lid of nails, which is a minor task as compared to existing approaches

Narrow-Band Microwave Filter Using High-Q Groove Gap Waveguide Resonators With Manufacturing Flexibility and No Sidewalls

This paper presents a new type of narrow band filter with good electrical performance and manufacturing flexibility, based on the newly introduced groove gap waveguide technology. The designed third and fifth-order filters work at Ku band with 1% fractional bandwidth. These filter structures are manufactured with an allowable gap between two metal blocks, in such a way that there is no requirement for electrical contact and alignment between the blocks. This is a major manufacturing advantage compared to normal rectangular waveguide filters. The measured results of the manufactured filters show reasonably good agreement with the full-wave simulated results, without any tuning or adjustments

Electromagnetic wormholes via handlebody constructions

Cloaking devices are prescriptions of electrostatic, optical or electromagnetic parameter fields (conductivity $\sigma(x)$, index of refraction $n(x)$, or electric permittivity $\epsilon(x)$ and magnetic permeability $\mu(x)$) which are piecewise smooth on $\mathbb R^3$ and singular on a hypersurface $\Sigma$, and such that objects in the region enclosed by $\Sigma$ are not detectable to external observation by waves. Here, we give related constructions of invisible tunnels, which allow electromagnetic waves to pass between possibly distant points, but with only the ends of the tunnels visible to electromagnetic imaging. Effectively, these change the topology of space with respect to solutions of Maxwell's equations, corresponding to attaching a handlebody to $\mathbb R^3$. The resulting devices thus function as electromagnetic wormholes.Comment: 25 pages, 6 figures (some color

Suppression of Parallel Plate Modes in Low Frequency Microstrip Circuit Packages Using Lid of Printed Zigzag Wires

This work deals with the suppression of parallel plate and cavity modes in shielded microstrip circuits operating at the lower microwave frequency range. The suppression is achieved by using a lid made of zigzag wires printed periodically on narrow slices of ungrounded circuit boards, located vertically side by side. This structure is very compact both in periodicity and height, it suppresses cavity modes over about an octave 2: 1 bandwidth, and it does not interfere with the packaged microstrip circuit

Bed of Springs for Packaging of Microstrip Circuits in the Microwave Frequency Range

After the use of the bed of nails for removing cavity modes in microstrip circuit packages, we propose herein a new version of this periodic structure, based on helices (springs) instead of nails. This new structure, named bed of springs, is much more compact, and this allows its use at low frequencies where the bed of nails is not suitable as it is too bulky due to the required height of the nails (pins). The bandwidth of the proposed structure turns out to be similar to the case of bed of nails. Parametric studies are presented as a design tool and a demonstrator is manufactured and measured

Design of integrated diplexer-power divider

A new configuration is introduced to integrate diplexers and power dividers. The proposed configuration is based on coupling matrix. The design of the lumped element network is based on addition of an extra term to the conventional error function of the coupling matrix to decouple the two ports of the power divider. An optimized lumped element network is implemented successfully on an EBG based guiding technology known as ridge gap waveguide. The optimization of the physical structure is done efficiently by dividing the diplexer-power divider into many sub-circuits and analyzing the corrected delay response of them

Analysis of the strut and feed blockage effects in radio telescopes with compact UWB feeds

The international radio astronomy community is currently pursuing the development of a giant radio telescope known as the Square Kilometre Array (SKA). The SKA reference design consists of several wideband antenna technologies, including reflector antennas fed with novel multi-beam Phased Array Feeds (PAF) and/or wide band Single Pixel Feeds (SPFs) that can operate at frequencies from 1 to 10 GHz [1], [2]. The baseline of this design represents an array of several hundred to a few thousand reflector antennas of 15-m diameter and that will realize sensitivity of 10,000 m 2/K. During the past years, several different reflector and feed concepts have been proposed and examined, but only a small number of these design options (that have a sufficient level of maturity) will be built and tested in a set-up that is closely resembling the final SKA system [3]. These tests are aimed to evaluate the overall system performance as well as construction and operational costs. The final choices for the dish and feed evaluation tests might include: (i) off-set Gregorian and axi-symmetric reflector antennas and; (ii) an optimized octave corrugated horn and the single-pixel wideband feeds such as quad-ridged horn and Eleven antenna [2], [4]