Absolute gain measurement by the image method under mismatched condition

Purcell's image method for measuring the absolute gain of an antenna is particularly attractive for small test antennas. The method is simple to use and utilizes only one antenna with a reflecting plane to provide an image for the receiving antenna. However, the method provides accurate results only if the antenna is matched to its waveguide. In this paper, a waveguide junction analysis is developed to determine the gain of an antenna under mismatched condition. Absolute gain measurements for two standard gain horn antennas have been carried out. Experimental results agree closely with published data

A dual frequency microstrip antenna for Ka band

For fixed satellite communication systems at Ka band with downlink at 17.7 to 20.2 GHz and uplink at 27.5 to 30.0 GHz, the focused optics and the unfocused optics configurations with monolithic phased array feeds have often been used to provide multiple fixed and multiple scanning spot beam coverages. It appears that a dual frequency microstrip antenna capable of transmitting and receiving simultaneously is highly desirable as an array feed element. This paper describes some early efforts on the development and experimental testing of a dual frequency annular microstrip antenna. The antenna has potential application for use in conjunction with a monolithic microwave integrated circuit device as an active radiating element in a phased array of phased array feeds. The antenna is designed to resonate at TM sub 12 and TM sub 13 modes and tuned with a circumferential microstrip ring to vary the frequency ratio. Radiation characteristics at both the high and low frequencies are examined. Experimental results including radiating patterns and swept frequency measurements are presented

Critical electrical aspects of alternating-current power source for Centaur space vehicle

Reliability of silicon rectifiers as inverters for alternating current power source for Atlas Centaur launch vehicle

The Discrete Hankel Transform

The Hankel transform is an integral transform and is also known as the Fourier-Bessel transform. Until recently, there was no established discrete version of the transform that observed the same sort of relationship to its continuous counterpart as the discrete Fourier transform does to the continuous Fourier transform. Previous definitions of a discrete Hankel transform (DHT) only focused on methods to approximate the integrals of the continuous Hankel integral transform. Recently published work has remedied this and this chapter presents this theory. Specifically, this chapter presents a theory of a DHT that is shown to arise from a discretization scheme based on the theory of Fourier-Bessel expansions. The standard set of shift, modulation, multiplication, and convolution rules are shown. In addition to being a discrete transform in its own right, this DHT can approximate the continuous forward and inverse Hankel transform

Banking in a Global Market: A Financial Institution Guide for Offering International Remittance Services

Provides a detailed overview of the U.S.-Latin America remittance market, and offers a step-by-step guide to setting up transparent and efficient remittance services. Includes summaries of six product approaches and profiles of programs at eleven banks

Platinum-containing heterobimetallic lantern complexes prepared with thiocarboxylates: synthesis, structural, and magnetic characterization and synthesis characterization of magnetic metal oxide nanoparticles

Three Pt-based heterobimetallic lantern complexes of the form, [PtM(SAc)4(OH2)], M = Co (1), Ni (2), Zn (3), were prepared with thioacetate (SAc^-) bridging ligands that exhibit short Pt^...Pt interactions in the solid state. Three compounds with the form [PtM(SAc)4(3-NO2py)], M = Co (4), Ni (5), Zn (6) are formed upon reaction with 3-nitropyridine (3-NO2py) or alternatively the hydrated species 1--3 could be dehydrated to form the species [PtM(SAc)4], M = Co (7), Ni (8), Zn (9). Solid-state magnetism measurements indicate antiferromagnetic coupling of the paramagnetic 3d metal centers that can be attributed to the pathway established by the short Pt^...Pt contacts. Additional families of thiocarboxylate lantern complexes were prepared via the reaction of 1--3 or 7--9 with nitrogen or oxygen donor ligands. Reaction of 7--9 with pyridine yielded complexes with the form [PtM(SAc)4(py)2], M = Co (10), Ni (11), Zn (12). Complexes 10--12 could be thermally converted to the complexes [PtM(SAc)4(py)], M = Co (13), Ni (14), Zn (15) respectively. Reactions with the 4-aminopyridine ligand (amp) yielded exclusively monopyridyl species of the form [PtM(SAc)4(amp)], M = Co (16), Ni (17), Zn (18). O-donor solvents bind the dehydrated core [PtM(SAc)4] to give the complexes [PtCo(SAc)4(DMSO)](DMSO), 19, and [PtNi(SAc)4(DMF)](DMF), 20. Several diamagnetic complexes were prepared with the form [PtM(SOCR)4OH2], R = CH3, M = Mg (21); R = C6H5, M = Mg (22), Ca (23), and Zn (24) to examine the effect of the 3d metal on the electronic environment as determined by ^195Pt NMR. An additional family of complexes were prepared with pyrazine (pyz) linker ligands to form coordination polymers of the form [PtM(SAc)4(pyz)]n M = Co (25), Ni (26), Zn (27) and [PtM(SAc)4(pyz)0.5]2 M = Co (28), Ni (29), Zn (30). Two novel diplatinum complexes have been prepared with the 2,6-dimercaptopyridine (H2dmp) protoligand of the form [Pt2(Hdmp)4], 31, and [Pt2(phen)2(Hdmp)2], 32. Finally, a facile synthesis for ricinoleic acid, RA, coated ferrite spinel nanoparticles MFe2O4 · RA, M = Mn (33), Co (34), Ni(35), Zn(36) has been developed. The ferrite spinels were prepared hydrothermally and the synthesis and characterization of these nanoparticles will be discussed