A new type of the quasi-TEM eigenmodes in a rectangular waveguide with one corrugated hard wall

The problem of determining the eigenmodes of a rectangular waveguide with one hard wall formed by longitudinal corrugations with grooves filled with dielectric is considered. The characteristic equation is derived by using the asymptotic boundary conditions for corrugated surfaces. It is shown analytically that if the groove depth is equal to the value 0.25 lambda/(epsilon - 1)(1/2) corresponding to the hard wall condition, the TE eigenmode spectrum of the waveguide contains an infinite set of new non-uniform quasi-TEM modes with different transverse propagation constants in the empty part and identical longitudinal propagation constants equal to the wavenumber k. Analytical solution for the case of excitation of the waveguide by a specified source is given, and an example of forming local quasi-TEM waves is considered and discussed

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

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

Diversity Characterization of Optimized Two-Antenna Systems for UMTS Handsets

This paper presents the evaluation of the diversity performance of several two-antenna systems for UMTS terminals. All the measurements are done in a reverberation chamber and in a Wheeler cap setup. First, a two-antenna system having poor isolation between its radiators is measured. Then, the performance of this structure is compared with two optimized structures having high isolation and high total efficiency, thanks to the implementation of a neutralization technique between the radiating elements. The key diversity parameters of all these systems are discussed, that is, the total efficiency of the antenna, the envelope correlation coefficient, the diversity gains, the mean effective gain (MEG), and the MEG ratio. The comparison of all these results is especially showing the benefit brought back by the neutralization technique

Full-wave invisibility of active devices at all frequencies

There has recently been considerable interest in the possibility, both theoretical and practical, of invisibility (or "cloaking") from observation by electromagnetic (EM) waves. Here, we prove invisibility, with respect to solutions of the Helmholtz and Maxwell's equations, for several constructions of cloaking devices. Previous results have either been on the level of ray tracing [Le,PSS] or at zero frequency [GLU2,GLU3], but recent numerical [CPSSP] and experimental [SMJCPSS] work has provided evidence for invisibility at frequency $k\ne 0$. We give two basic constructions for cloaking a region $D$ contained in a domain $\Omega$ from measurements of Cauchy data of waves at \p \Omega; we pay particular attention to cloaking not just a passive object, but an active device within $D$, interpreted as a collection of sources and sinks or an internal current.Comment: Final revision; to appear in Commun. in Math. Physic

ACBAR: The Arcminute Cosmology Bolometer Array Receiver

We describe the Arcminute Cosmology Bolometer Array Receiver (ACBAR); a multifrequency millimeter-wave receiver designed for observations of the Cosmic Microwave Background (CMB) and the Sunyaev-Zel'dovich effect in clusters of galaxies. The ACBAR focal plane consists of a 16-pixel, background-limited, 240 mK bolometer array that can be configured to observe simultaneously at 150, 220, 280, and 350 GHz. With 4-5' FWHM Gaussian beam sizes and a 3 degree azimuth chop, ACBAR is sensitive to a wide range of angular scales. ACBAR was installed on the 2 m Viper telescope at the South Pole in January 2001. We describe the design of the instrument and its performance during the 2001 and 2002 observing seasons.Comment: 59 pages, 16 figures -- updated to reflect version published in ApJ

MED12 Alterations in Both Human Benign and Malignant Uterine Soft Tissue Tumors

The relationship between benign uterine leiomyomas and their malignant counterparts, i.e. leiomyosarcomas and smooth muscle tumors of uncertain malignant potential (STUMP), is still poorly understood. The idea that a leiomyosarcoma could derive from a leiomyoma is still controversial. Recently MED12 mutations have been reported in uterine leiomyomas. In this study we asked whether such mutations could also be involved in leiomyosarcomas and STUMP oncogenesis. For this purpose we examined 33 uterine mesenchymal tumors by sequencing the hot-spot mutation region of MED12. We determined that MED12 is altered in 66.6% of typical leiomyomas as previously reported but also in 11% of STUMP and 20% of leiomyosarcomas. The mutated allele is predominantly expressed in leiomyomas and STUMP. Interestingly all classical leiomyomas exhibit MED12 protein expression while 40% of atypical leiomyomas, 50% of STUMP and 80% of leiomyosarcomas (among them the two mutated ones) do not express MED12. All these tumors without protein expression exhibit complex genomic profiles. No mutations and no expression loss were identified in an additional series of 38 non-uterine leiomyosarcomas. MED12 mutations are not exclusive to leiomyomas but seem to be specific to uterine malignancies. A previous study has suggested that MED12 mutations in leiomyomas could lead to Wnt/β-catenin pathway activation however our immunohistochemistry results show that there is no association between MED12 status and β-catenin nuclear/cytoplasmic localization. Collectively, our results show that subgroups of benign and malignant tumors share a common genetics. We propose here that MED12 alterations could be implicated in the development of smooth muscle tumor and that its expression could be inhibited in malignant tumors

Expression profiling identifies genes involved in neoplastic transformation of serous ovarian cancer

Background: The malignant potential of serous ovarian tumors, the most common ovarian tumor subtype, varies from benign to low malignant potential (LMP) tumors to frankly invasive cancers. Given the uncertainty about the relationship between these different forms, we compared their patterns of gene expression. Methods: Expression profiling was carried out on samples of 7 benign, 7 LMP and 28 invasive (moderate and poorly differentiated) serous tumors and four whole normal ovaries using oligonucleotide microarrays representing over 21,000 genes. Results: We identified 311 transcripts that distinguished invasive from benign tumors, and 20 transcripts that were significantly differentially expressed between invasive and LMP tumors at p < 0.01 (with multiple testing correction). Five genes that were differentially expressed between invasive and either benign or normal tissues were validated by real time PCR in an independent panel of 46 serous tumors (4 benign, 7 LMP, 35 invasive). Overexpression of SLPI and WNT7A and down-regulation of C6orf31, PDGFRA and GLTSCR2 were measured in invasive and LMP compared with benign and normal tissues. Over-expression of WNT7A in an ovarian cancer cell line led to increased migration and invasive capacity. Conclusion: These results highlight several genes that may play an important role across the spectrum of serous ovarian tumorigenesis

Malignant germ cell tumours of childhood: new associations of genomic imbalance

Malignant germ cell tumours (MGCTs) of childhood are a rare group of neoplasms that comprise many histological subtypes and arise at numerous different sites. Genomic imbalances have been described in these tumours but, largely because of the paucity of cases reported in the literature, it is unclear how they relate to abnormalities in adult MGCTs and impact on potential systems for classifying GCTs. We have used metaphase-based comparative genomic hybridisation to analyse the largest series of paediatric MGCTs reported to date, representing 34 primary tumours (22 yolk sac tumours (YSTs), 11 germinomatous tumours and one metastatic embryonal carcinoma) occurring in children from birth to age 16, including 17 ovarian MGCTs. The large dataset enabled us to undertake statistical analysis, with the aim of identifying associations worthy of further investigation between patterns of genomic imbalance and clinicopathological parameters. The YSTs showed an increased frequency of 1p- (P=0.003), 3p+ (P=0.02), 4q− (P=0.07) and 6q− (P=0.004) compared to germinomatous tumours. Gain of 12p, which is invariably seen in adult MGCTs, was present in 53% of primary MGCTs of children aged 5–16 and was also observed in four of 14 YSTs affecting children less than 5. Two of these cases (14% of MGCTs in children less than 5) showed gain of the 12p11 locus considered to be particularly relevant in adult MGCTs. Gain of 12p showed a significant association with gain of 12q. Conversely, MGCTs without 12p gain displayed a significantly increased frequency of loss on 16p (P=0.04), suggesting that this imbalance may contribute to tumour development in such cases. This data provides new insight into the biology of this under-investigated tumour group and will direct future studies on the significance of specific genetic abnormalities