Open Access
Optimum horn antennas for high order mode beam waveguides
(1995) Río Bocio, Carlos del; Gonzalo García, Ramón; Sorolla Ayza, Mario; Thumm, Manfred; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
Higher order free space modes can be considered as serious candidates for power millimeter wave transmission in advanced material processing by using medium power CW gyrotrons. These modes can be propagated in a beam waveguide with properly designed mirrors. Here, we present some optimal ways to excite these higher order free space modes from circular symmetric cylindrical waveguide modes by using optimal non linear horn launchers. An original synthesis procedure is proposed which has been successfully tested by computational simulation.
Open Access
Estudio de la posibilidad de utilizar modos de orden superior en guías de onda cuasi-ópticas
(1995) Río Bocio, Carlos del; Gonzalo García, Ramón; Marín Pilz, Miguel; Sorolla Ayza, Mario; Möbius, Arnold; Thumm, Manfred; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
The possibility to employ low power gyrotron tubes (10-30 kW, CW) at millimeter wave frequencies (30-100 GHz) has potential applications in advanced ceramic sintering, surface coating, radar, remote sensing, etc.. In materials processing applications, the final shape of the beam is not relevant, because the experiment have to be done in a cavity which has a metallic mode stirrer in order to obtain inside a uniform distribution of the electromagnetic fields. In this paper, we present a preliminar study, showing that it is possible to use high order modes in the transmission line to carry the power to the final experiment efficiently.
Open Access
Paraxiality considerations of higher order gaussian modes
(1996) Río Bocio, Carlos del; Gonzalo García, Ramón; Sorolla Ayza, Mario; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
Frequently, gaussian modes are used as free space wave equation solutions. This is not true since they are obtained assuming certain paraxial character in them. In this paper, we present an original study of the condition for paraxiality of higher order gaussian modes solutions of the wave equations in free space. A bound for the product of number (k) in free space and the beam waist of a family of modes is obtained, in terms of the mode indexes - the bound being more restrictive the larger the order of the mode.
Open Access
Gaussian beam propagation versus Huygens method in non-paraxial conditions
(1997) Gonzalo García, Ramón; Turullols, Pedro; Río Bocio, Carlos del; Sorolla Ayza, Mario; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this paper, we present a study about the difference between Gaussian beam propagation and Huygens method to obtain the radiation pattern in the case of non-paraxial conditions. We fix a way to determine the error in the Gaussian beam propagation, in this way, we could know if the approximation is good enough. The computational results show that it is not possible to use the Gaussian propagation equation when we are working with Gaussian beams in non-paraxial conditions.
Open Access
High order mode beam waveguide for technological medium power millimeter wave applications
(1995) Río Bocio, Carlos del; Gonzalo García, Ramón; Marín Pilz, Miguel; Sorolla Ayza, Mario; Möbius, Arnold; Thumm, Manfred; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
The use of medium power millimeter wave CW gyrotrons (10- 30 kW and 30-100 GHz) has several potential applications in advanced materials processing. Since a stochastic field distribution in the applicator is desirable no pencil beam is necessary. Then the possibility to couple the circular symmetric gyrotron output to a higher order free space mode can be considered. Beam waveguides based on iterative reflection of such high order beams on properly designed mirrors opens the possibility to increase the efficiency and to reduce costs of present compact transmission lines in gyrotron technological systems.
Open Access
Generación del modo HE11 a partir de una guía circular lisa monomodo
(1996) Gonzalo García, Ramón; Río Bocio, Carlos del; Teniente Vallinas, Jorge; Sorolla Ayza, Mario; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this paper, we present an original taper design to obtain the HE11 corrugated circular waveguide mode exciting with a pure TE11 monomode smooth circular waveguide mode. The proposed corrugated taper has a longitudinal section composed of two hyperbolic profiles in series, one concave and the other convex united at a point, such that the derivative is continuous. Superimposed there is an additional tapering of the corrugation depth that goes from l/2 at taper input to l/4 within the first hyperbola. This original synthesis procedure has been successfully tested by computational simulation. The calculation method has been validated by experimental results of other authors.
Open Access
Measurements of a new gaussian profile corrugated horn antenna for millimeter wave applications
(IEEE, 1998) Gonzalo García, Ramón; Martí Canales, J.; Teniente Vallinas, Jorge; Río Bocio, Carlos del; Sorolla Ayza, Mario; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
The measurements results of a new design of corrugated horn antennas [1, 2, 3] following the gaussian expansion are presented in this paper. The performance of two corrugated horn antennas of this kind was verified in the ESTEC Compact Antenna Test Range (CATR) [4]. Very high agreement between measured and predicted results is found.
Open Access
Diseño de guías de onda cuasi-ópticas para modos gaussianos de orden superior
(1996) Río Bocio, Carlos del; Sorolla Ayza, Mario; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
En este trabajo se presenta un nuevo método de diseño de guías de onda cuasi-ópticas para modos gaussianos, a frecuencias milimétricas. En concreto, se centrará en la generación de modos gaussianos de orden superior, como posibles candidatos a ser portadores de la energía a través de la línea de transmisión cuasi-óptica. Para lograrlo, se presenta un perfil de antena óptimo para la excitación de modos gaussianos de orden superior, a partir de modos de guía de onda convencional. Este perfil, además de conseguir estructuras gaussianas de alta pureza, adapta óptimamente las estructuras de guías de onda con el espacio libre. La idea de diseño es absolutamente general, por lo que puede ser aplicable a guías de onda rectangulares, ya sean corrugadas o no. El abanico de aplicaciones de este tipo de antenas es muy grande, ya que se pueden utilizar como alimentadoras de líneas de transmisión cuasi-ópticas, como alimentadores de antenas parabólicas para la emisión y/o recepción de señales via satélite, etc. En cuanto al diseño de reflectores, se comprueba la existencia, bajo ciertas condiciones (paraxialidad), de una compatibilidad total de los diseños de guías de onda cuasi-ópticas para modos de orden superior con los diseños clásicos para el modo gaussiano fundamental. Se estudian las estructuras de los modos gaussianos de orden superior, definiendo unos nuevos límites de paraxialidad para estos modos superiores. Finalemente, a modo de validación, se ha podido diseñar, construir y medir, la primera línea cuasi-óptica que utiliza un modo gaussiano de orden superior para transportar la potencia entre un generador de microondas y un aplicador o cavidad final. Se ha obtenido una buena concordancia entre los resultados de la simulación y los medidos experimentalmente.
Open Access
Diseño óptimo de antenas de bocina multimodo para excitar un haz gaussiano fundamental de alta pureza
(1996) Gonzalo García, Ramón; Río Bocio, Carlos del; Teniente Vallinas, Jorge; Sorolla Ayza, Mario; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this paper, we present an original and optimal multimode horn antenna design to excite the fundamental Gaussian beam from an overmoded waveguide. In particular, we focus the study in overmoded circular corrugated waveguide. The main idea to design this multimode horn antenna, is to increase the waveguide radius as the desired gaussian mode expands. This principle has also been applied to smooth circular waveguides to excite higher order Gaussian beams from TE0n modes. The horn antenna design considered here, improves the gaussian conversion efficiency, the crosspolarisation and the sidelobes level of some good mixture ( aprox. 85% of TE11 and 15% of TM11 ).
Open Access
New approach to the design of corrugated horn antennas
(1997) Gonzalo García, Ramón; Teniente Vallinas, Jorge; Río Bocio, Carlos del; Sorolla Ayza, Mario; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this paper, we present two new corrugated horn antenna designs in circular waveguide. The first one is a converter horn antenna from monomode circular waveguide TE11 to corrugated waveguide HE11 mode in a very efficient way. The conversion efficiency varies between 98 % and 99%. The HE11 mode has highly desired radiation pattern characteristics for applications like satellite communications, radar, remote- sensing, etc, nevertheless, when the requirements are more stringent this mode is not good enough and we must look for other solution. This one corresponds to the fundamental gaussian beam, which has outstanding features, such as being a free space mode, having high matching efficiency with a reflector, no sidelobes, perfect symmetry, etc. The second horn antenna presented generates very efficient fundamental gaussian beams at the output (99%-99.9%). It is important to say that the input must look like a gaussian beam, an HE11 for instance, which presents a 98.4% of gaussian beam or similar. We also show a new design in which we are working now, consisting in the junction of the two aforementioned designs. They form an unique horn antenna that results in the TE11 mode, from the fundamental gaussian beam mode. These components have been analysed using the Mode Matching and the Generalised Scattering Matrix techniques and the Moment Method as well as the equations in [1] to get the far field radiation pattern. Our results have been checked against those obtained by other authors.