Front-to-back ratio of paraboloidal reflectors

An analysis is presented which uses the uniform geometrical theory of diffraction for determining the near fields diffracted by a paraboloid either with or without a conical flange attached to its circular rim when an axially propagated plane wave is incident on the concave or convex portion of the paraboloidal reflector. The field correlation theorem is used to determine the power coupled by a prime focus feed associated with the paraboloid which is being illuminated by a uniform plane wave. Based on this analysis, the front-to-back ratio of unflanged and flanged paraboloids is computed. Computed results show satisfactory agreement with the available measured as well as computed results based on alternative procedures. The variation in the on-axis gain on a prime-focus reflector when the feed is displaced from the focus is studied. Typical computed results are presented and compared with the available measured data. Computed results on the front-to-back ratio of paraboloids (flanged or unflanged) illuminated by a PFF whose radiated field exhibits phase variation over a constant radius are also presented     

Radiation pattern of a lens-corrected conical scalar horn

An expression for the radiation pattern of a lens-corrected conical scalar horn is derived. Computed radiation patterns are presented for scalar-horns feeds containing planoconvex and meniscus lenses in their apertures. The patterns and beamwidths are compared with those of an uncorrected wide-angle scalar horn and an open-ended corrugated waveguide.     

Sum and tracking radiation patterns of a conical horn

The gain and the radiation patterns of a conical horn excited by a circular waveguide operating in theTE_{mn}andTM_{mn}modes are predicted. The expressions are rigorously derived by using the accurate calculation of the associated Legendre function with the real order and the integer degree.     

Paraboloidal reflector offset fed with a corrugated conical horn

A paraboloidal reflector, offset fed with a corrugated conical horn, has been examined as a possible antenna for use in millimeter wave communications systems when minimization of interference is an important consideration. Low far-out and back-lobe radiation were primary objectives. Experimentally obtained data, representative of performance at 37 GHz, is presented. When appropriately shielded to limit spillover, levels more than 75 dB below the main beam maximum have been obtained in the far-out and back-lobe regions.     

Vector boundary-element analysis for conical horn

A vector boundary-element method is developed for analyzing a conical horn in this paper. A moving boundary technique (MBT) is proposed for solving difficulties of the integration at high-order singularity points in a vector integral equation, and its validity is verified by calculating the reflection coefficients of an empty circular waveguide with a short-end. The circular symmetry of the conical horn is utilized to simplify the 3-D problem to 2-D one and the analyzing efficiency is significantly improved. A comparison of the reflection coefficients of the conical horn is given between the experimental data and the calculated results. Very good agreement has been seen, and the reliability and efficiency of the present method are thus verified.     

The electrical characteristics of a conical horn-reflector antennaemploying a corrugated horn

The electrical properties of a conical horn-reflector antenna of 2-3° beamwidth have been investigated over the frequency range of 12-18 GHz. It is shown that the employment of a corrugated horn reduces the characteristic spillover side lobe of the conical horn-reflector antenna by 15 dB and yields excellent main beam circularity over the full Ku band. This results from the taper of the field amplitude toward the edges of the horn aperture in both the E-plane and the H-plane illumination. The performance of the antenna makes it suitable for use in closely packed interferometers for radio astronomy     

Analysis of a conical horn fed by a slightly oversized waveguide

This paper discusses the case of a submillimetre conical feedhorn system which is overmoded due to an oversized waveguide, but is not in the geometric optics regime. The motivation for this system is to use the same feed as a multi-frequency receiver. Increased background loading is the greatest disadvantage in overmoded optics; and aperture efficiency also suffers due to non-optimum horn dimensions. The analysis is done using the Laguerre-Gauss beam expansion method.     

Computation of eigenvalues for higher-order modes in a conical horn

A special expansion for the associated Legendre functions and their derivatives is employed to compute the integer eigenvalues for higher-order modes in a conical horn. The resulting plot of these eigenvalues, as a function of horn flare angle, is used to provide graphically the noninteger values corresponding to other flare angles of the horn.     

Analysis of spherical hybrid modes in a corrugated conical horn

An approximate analysis of fields in a corrugated horn is considered using spherical hybrid modes. Under the special condition where the slots are about a quarter-wavelength deep, the approximations are slight in the far-field region of the horn. Solutions are presented for the lowest-order spherical hybrid modes, and a procedure is described for the determination of the horn radiation pattern. A first step in the procedure involves the calculation of the hybrid-mode field in the horn aperture. Because diffraction will be minimal in wide-angle corrugated horns, the aperture and radiation patterns should be similar when the far-field approximation applies. This feature is verified for a 120° horn making use of experimental results due to Kay.     

Corrugated conical horn as a space feed for phased-array illumination

The importance of corrugated conical horns in space-fed illumination of phased arrays is indicated. Design details pertaining to corrugated conical horns of optimum proportions for uniform illumination of a phased array with a prescribed area are also presented.     

CORRUGATED CONICAL HORN FOR MULTI-FREQUENCY BAND USE

The theory of corrugated conical horn operating at multi-frequency bands is described,and aprqactical corrugated conical horn is constructed.It can operate at three frequency bands(4,6,11 GHz)atleast.The cross polarization peak level is better than -25 dB at 4,6 GHz frequency bands,and the amplitudepattern at 11 GHz frequency band is also very good.It is shown theoretically and experimentally that thecorrugated conical horn operating at multi-frequency bands is the best condidate for multi-frequency bandfeeds.     

Surface waves in the corrugated conical horn

An investigation of the existence of surface waves has been carried out. The conclusion is that surface waves can propagate in such a structure provided that the depth of the grooves is less than one-quarter of a wavelength.     

Improvement of conical corrugated horn analysis using Gaussianbeams

The classical analysis of a conical corrugated horn is extended out of the balanced hybrid conditions using a vectorial multimodal Gaussian beam expansion. An experimental validation is also presented     

Radiation pattern of a corrugated conical horn in terms of Laguerre-Gaussian functions

Many papers can be found on radiation properties of corrugated feeds. The radiated field is described either by means of the Kirchhoff-Huyghens formula, or with a spherical mode expansion. In both cases, especially where the horn is long, the computation may be important. In this letter we present a third method founded on a Laguerre-Gaussian expansion in cylindrical coordinates.     

Dual-band and dual-polarised horn antenna including conical helix

A horn antenna having dual-band and dual-polarisation operation is proposed. To implement a small-sized structure providing circular polarisations in the Ka- and K-band, the antenna is designed using the horn radiator on the basis of a conical helix which is exited by two ports for TX and RX in both ends. Through a design optimisation process, a compact dual-band and dual-polarised horn antenna having high gain and high isolation performance was realised     

On the fields in a conical horn having an arbitrary wall impedance

The electromagnetic fields propagating up a cone having an arbitrary wall impedance are found using an asymptotic solution. Three special cases are then considered: the smooth-metal wall, the corrugated wall, and the metal wall with a lossy-dielectric lining. The last case, in the form of an absorber-lining is then shown to behave like a corrugated horn since it too provides a highly taperedE-plane andH-plane aperture distribution. Furthermore, it does this over a much larger bandwidth, over 3:1, with negligible gain drop.     

Characteristics of a Schottky-barrier diode mixer with conical horn antenna for submillimeter wavelengths

Antenna characteristics and noise performance of an improved quasi-optical Schottky-barrier diode mixer have been investigated at 800 GHz. We present both calculated and measured antenna patterns. Numerical values are given for the powers radiated in two orthogonal polarizations and for the main beam efficiencies. Measurements indicate that system noise can be reduced by about 25% by adding a conical-horn structure to a corner-cube mixer.     

Propagation and radiation behavior of dielectric-loaded pluralhybrid mode multiflare conical horn antennas

A dielectric-loaded multiflare conical horn exhibiting the desirable features of low sidelobes and cross-polarization with the additional advantage of increased on-axis gain is reported. This new horn is developed by combining the techniques of multimode operation for low cross-polarization and sidelobe levels, and dielectric loading for aperture efficiency enhancement. The condition for the support of balanced hybrid modes for low cross polar radiation in the dielectric-loaded multimode horn is derived. Also, the equation for the dielectric thickness for maximum aperture efficiency at a given frequency is obtained. This new type of multimode horn is potentially simple to design, analyze, and manufacture, yet it exhibits the desirable features of a corrugated conical horn and hence can be an attractive alternative to corrugated conical horns for communication applications     

Transients in a resistively loaded linear antenna compared with those in a conical antenna and a TEM horn

The receiving and transmitting transient responses of the resistively loaded linear antenna, the TEM horn, and the conical antenna are investigated theoretically and experimentally using the fast Fourier transform (FFT) technique. The receiving transient response of the resistively loaded linear antenna indicates that the shape of a 70-ps impulse is well preserved.