General Field Theory Treatment of H-Plane Waveguide Junction Circulators
TL;DR: In this article, an exact field theory treatment for the waveguide junction circulators is presented, being dependent on neither the geometrical symmetry of the junction nor the number of ports.
Abstract: In this paper an exact field theory treatment for the waveguide junction circulators is presented. The treatment is general, being dependent on neither the geometrical symmetry of the junction nor the number of ports. The electromagnetic fields in the joining waveguides are written in the form of infinite summation of waveguide modes. The solutions of the wave equations in the ferrite rod and in the surrounding air are obtained in the form of infinite summation of cylindrical modes. The fields at the ferrite air interface and at an imaginary boundary chosen arbitrarily between the air region and the waveguides are then matched. This process leads to an infinite system of nonhomogeneous equations in the field amplitudes. Three types of waveguide junction circulators using this technique are analyzed: the simple ferrite-rod Y junction, the simple ferrite-rod T junction, and the latching Y junction. Point-matching techniques are used to get numerical results for the field distributions and the circulator characteristics. Excellent agreement has been found between the published experimental measurements and the numerical results obtained by this technique.
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TL;DR: In this article, a numerical approach for solving the problem of H-plane waveguide junctions with Iossy ferrite posts of arbitrary shape is proposed, where the junctions are allowed to have arbitrary cross section.
Abstract: A numerical approach for solving the problem of H-plane waveguide junctions with Iossy ferrite posts of arbitrary shape is proposed. The junctions are allowed to have arbitrary cross section. The approach is a combination of the finite-element method and the analytical method. To show the validity and usefulness of tbe method, Y-junction circulators with a circular ferrite post are considered. Our results agree well with earlier experimental and theoretical results. The performances of Y-junction circulators with a triangular equilateral ferrite post or a triangular ferrite post having depressed sides are investigated. The influences of the ferrite losses on the performance are examined.
72 citations
TL;DR: In this paper, an exact field theory treatment for the H-plane waveguide junction with three-sided ferrite prism is presented, being independent of the geometrical symmetry of the junction, the number of ports, and the location of the ferrite post inside the junction.
Abstract: This paper presents an exact field theory treatment for the H-plane waveguide junction with three-sided ferrite prism. The treatment is general, being independent of the geometrical symmetry of the junction, the number of ports, and the location of the ferrite post inside the junction. The solution of the wave equations in the ferrite post and in the surrounding region is written in the form of an infinite summation of cylindrical modes. The fields at the ferrite-air interface are matched using the point-matching technique. This results in two amplitudes for the cylindrical modes describing the fields in the air region in the form of a matrix. The fields at the arbitrary boundary between the air region and the waveguides are also matched using the point-matching technique. This results in a finite system of nonhomogeneous equations in the field amplitudes. The three-port waveguide junction circulator with central triangular ferrite post is analyzed using this technique. Two specific arrangements are considered. In the first arrangement, the points of the triangles are in the centers of the waveguides, and in the second, the sides of the triangles are in the centers of the waveguides. The method used in this paper can also be applied to study the effect of the ferrite-post geometry on the circulator performance in order to seek the best possible circulator structure. Excellent agreement has been found between published experimental measurements and the numerical results obtained by this technique in the case of a waveguide junction circulator with cylindrical ferrite post.
38 citations
TL;DR: In this article, a design procedure for the widely used three-port waveguide circulator that has a partial height ferrite post in the junction region is presented, and the design formulas and curves are derived for two configurations of partial height circulators: one has a short circuit at one end, while the other has dielectric spacers at both ends.
Abstract: This short paper presents a design procedure for the widely used three-port waveguide circulator that has a partial height ferrite post in the junction region Design formulas and curves are derived for two configurations of partial height circulators: one has a short circuit at one end of the ferrite post, while the other has dielectric spacers at both ends The design method was used to build two circulators for operation at 38 GHz and 60 GHz, respectively Excellent agreement between theory and experiment was obtained in predicting the center frequency and required matching structure of these devices
36 citations
TL;DR: In this paper, a three-dimensional modeling strategy using a self-inconsistent mixed-coordinates-based modal field-matching procedure is developed to characterize electrical performance of the proposed circulator.
Abstract: This paper presents a class of new easy-to-fabricate ferrite-sphere-based waveguide Y-junction circulators for potentially low-cost millimeter-wave applications. A new three-dimensional modeling strategy using a self-inconsistent mixed-coordinates-based modal field-matching procedure is developed to characterize electrical performance of the proposed circulator. It is found that the circulating mechanism of the ferrite-sphere post is different from its full-height ferrite counterpart in that the new structure operates in a turnstile fashion with resonant characteristics, while the conventional device operates on a transmission cavity model. Extensive comparable studies between the new and conventional circulators are made to show that the electrical behaviors of the new structure are also distinct and radial power-density profiles are not stationary, as in the case of the full-height ferrite post circulator for different geometrical parameters. Results obtained by the analysis technique are compared with the available results for a full/partial-height ferrite circulator, showing an excellent agreement. Our calculated and measured results are also presented for W-band circulators with the proposed ferrite-sphere technique, indicating some interesting characteristics such as the frequency offset behavior of the isolation and reflection curves. In addition, radial power-density profiles are plotted inside and outside the ferrite sphere to illustrate its intrinsic circulating mechanism, as well as its difference, as compared to its full-height ferrite structure.
29 citations
Cites background or result from "General Field Theory Treatment of H..."
...The field matching related to this boundary has been discussed in [3] and [4]....
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...However, we will not discuss this here for the sake of brevity, and interested readers may refer to [3], [4], [15], and [16] for details....
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...A number of techniques [3]–[7] were then proposed to model the waveguide-junction circulators having a full-height ferrite post with arbitrary shape....
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...3(a) shows our frequency-dependent results compared to the -band theoretical results reported in [3] for the full-height case, indicating an excellent agreement....
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...5 cm, (TT1-109), — our results, +++ [3]....
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TL;DR: In this article, an exact field theory treatment for the N-port E-plane full-height ferrite rod junction circulators is presented, where field expressions are written in each region of the junction in the form of infinite modes, and point matching of the fields at the common boundaries is used to get a set of infinite nonhomogeneous equations in these mode amplitudes.
Abstract: In this paper an exact field theory treatment for the N-port E-plane full-height ferrite rod junction circulators is presented. Field expressions are written in each region of the junction in the form of infinite modes. Matching of the fields at the common boundaries is used to get a set of infinite nonhomogeneous equations in these mode amplitudes. The point matching technique is used to obtain an approximate solution for the field amplitudes by taking a finite number of modes in each region. Three types of junctions have been analyzed by this technique. These junctions are the symmetrical Y junction and two types of T junctions. Experimental measurements have been carried out to verify the obtained numerical results.
26 citations
References
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TL;DR: In this article, an exact solution for the m-port symmetrical H-plane waveguide junction with central ferrite post is presented, from which an approximation that is equivalent to considering only the propagating modes of the rectangular waveguides is derived.
Abstract: An analysis is presented for the m-port symmetrical H-plane waveguide junction with central ferrite post. It has application to the engineering problem of microwave circulators and to the more academic problem of the empty symmetrical junction. An exact solution is formulated from which is developed an approximation that is equivalent to considering only the propagating modes of the rectangular waveguides. The method is found to give results in agreement with the theory for the 2-port junction (i. e., waveguide) with ferrite post, and with experiment for ferrite-free 3- and 4-port junctions. Theoretical design curves are given for the 3-port circulator, although for lack of suitable ferrite data, these have not been checked accurately. A number of 3- and 4-port circulators have been made to designs arising from the analysis. Because the microwave performance is derived explicitly in terms of the junction geometry and ferrite properties, the design of a particular component must of necessity involve much computation.
65 citations
TL;DR: In this paper, it is shown that inattention to the limits of validity of a field expansion can lead to field matching along impermissible boundaries, and that the error may not show up in any obvious way, since the method amounts to an expansion in terms of an incomplete modal set.
Abstract: It is shown that inattention to the limits of validity of a field expansion can lead to field matching along impermissible boundaries. Nevertheless the error may not show up in any obvious way, since the method amounts to an expansion in terms of an incomplete modal set. The "diffusion" of a discrete mode into a continuum takes place in a distance which may be of the order of a tenth of a wavelength or more, so that in fact fairly accurate numerical results can nevertheless ensue over quite a range of parameters. This would seem to be the case for some examples taken from the literature in which the analysis has apparently been undertaken on the assumption that the initial formulation was exact.
58 citations
TL;DR: The point-matching method as mentioned in this paper applies to the problem of wave propagation in many uniform waveguides of very general cross-sections, where boundary conditions are satisfied at a finite number of points on the guide wall only.
Abstract: The point-matching method applies to the problem of wave propagation in many uniform waveguides of very general cross-sections. The boundary conditions are satisfied at a finite number of points on the guide wall only. This method applies when the contour of the cross section of the guide is a closed curve, the function of which is single-valued. The validity of the point-matching method is demonstrated qualitatively. Examples show that accurate values of cutoff wave numbers can be achieved easily.
54 citations
05 May 1969
TL;DR: In this article, the performance of a lossless three-port H-plane waveguide junction loaded coaxially with various inhomogeneous ferrite cylanders has been evaluated over the waveguide bandwidth and compared with experiment.
Abstract: The complete performance of a lossless three-port H-plane waveguide junction loaded coaxially with various inhomogeneous ferrite cylanders has been evaluated over the waveguide bandwidth and compared with experiment. Qualitative agreement between the predicted and measured performance was generally good using only the first three modes, n=0/spl plusmn/1. It has been shown theoretically and verified experimentally that if the 4/spl pi/M/sub s/ of a homogeneous rod or the internal field is increased, the circulation frequency f/sub 0/ increases; conversely, if the pemittivity is increased, f/sub 0/ decreases. These conflicting effects are modified when the magnetization 4/spl pi/M/sub s/ and permittivity /spl epsiv/ are inhomogeneous. For example, if the 4/spl pi/M/sub s/(/spl gamma/) is small at the outer surface of the rod (with permittivity held constant), the effect on f/sub 0/ is very small; but if 4/spl pi/M/sub s/(spl gamma) approaches zero for /spl gamma/ small, then f/sub 0/ may decrease significantly. On the other hand, if /spl epsiv//sub/spl gamma//(/spl gamma/) approaches unity near the outer surface of the rod, f/sub 0/ may increase significantly; but if /spl epsiv//sub/spl gamma//(/spl gamma/) approaches unity near the center of the rod, f/sub 0/ is affected relatively little. The inhomogeneous structure has also shown that decreasing the ferrite volume may improve the performance, and high-power applications are suggested. With a conducting pin down the center of the ferrite, relative bandwidths of 40-50 percent are predicted.
53 citations
11 May 1970
TL;DR: Attention is drawn to recent work in which the use of a sutliciently smooth spectral expansion is shown to be able to convert a series of divergent terms into a usable convergent series, permitting valid numerical computations with otherwise divergent representations.
Abstract: The usefulness of point matching when the expansion representing the field diverges in the matching region is discussed in relation to previous work. It is shown that the presence of a metal boundary does not necessarily imply divergence of series representations at the boundary position. The Rayleigh hypothesis, which bears on this, and the extended-boundary-condition method are equivalent only in a restricted sense; the latter is hypersensitive to minute deviations of the field on the reduced boundary and is therefore unsuited to point matching for some shapes. A numerical example is examined in which the use of a divergent series gives little evidence of error from use in the divergent region. Attention is drawn to recent work in which the use of a sutliciently smooth spectral expansion is shown to be able to convert a series of divergent terms into a usable convergent series, permitting valid numerical computations with otherwise divergent representations.
42 citations