Topic

# Antenna aperture

About: Antenna aperture is a research topic. Over the lifetime, 8781 publications have been published within this topic receiving 120545 citations.

##### Papers published on a yearly basis

##### Papers

More filters

••

[...]

TL;DR: In this paper, the physical limitations of omni-directional antennas are considered and the potentiality of a broad band width of an antenna with the maximum dimension of 2a has been shown.

Abstract: The physical limitations of omni‐directional antennas are considered. With the use of the spherical wave functions to describe the field, the directivity gain G and the Q of an unspecified antenna are calculated under idealized conditions. To obtain the optimum performance, three criteria are used, (1) maximum gain for a given complexity of the antenna structure, (2) minimum Q, (3) maximum ratio of G/Q. It is found that an antenna of which the maximum dimension is 2a has the potentiality of a broad band width provided that the gain is equal to or less than 4a/λ. To obtain a gain higher than this value, the Q of the antenna increases at an astronomical rate. The antenna which has potentially the broadest band width of all omni‐directional antennas is one which has a radiation pattern corresponding to that of an infinitesimally small dipole.

1,844 citations

••

[...]

01 Dec 1947

TL;DR: In this paper, a simple formula for the more fundamental properties of small antennas and their behavior in a simple circuit is given for 1-Mc operation in typical circuits, which indicates a loss of about 35 db for the I.R.E. standard capacitive antenna, 43 db for a large loop occupying a volume of 1 meter square by 0.5 meter axial length, and 64 db for an antenna loop of 1/5 these dimensions.

Abstract: A capacitor or inductor operating as a small antenna is theoretically capable of intercepting a certain amount of power, independent of its size, on the assumption of tuning without circuit loss. The practical efficiency relative to this ideal is limited by the "radiation power factor" of the antenna as compared with the power factor and bandwidth of the antenna tuning. The radiation power factor of either kind of antenna is somewhat greater than (1/6π) (Ab/l2) in which Ab is the cylindrical volume occupied by the antenna, and l is the radianlength (defined as 1/2π wavelength) at the operating frequency. The efficiency is further limited by the closeness of coupling of the antenna with its tuner. Other simple formulas are given for the more fundamental properties of small antennas and their behavior in a simple circuit. Examples for 1-Mc. operation in typical circuits indicate a loss of about 35 db for the I.R.E. standard capacitive antenna, 43 db for a large loop occupying a volume of 1 meter square by 0.5 meter axial length, and 64 db for a loop of 1/5 these dimensions.

1,151 citations

••

[...]

TL;DR: The theoretical basis of antenna tolerance theory is reviewed in this paper, where the axial loss of gain and pattern degradation as a function of the reflector surface rms error and the surface spatial correlation are discussed.

Abstract: The theoretical basis of antenna tolerance theory is reviewed. Formulas are presented for the axial loss of gain and the pattern degradation as a function of the reflector surface rms error and the surface spatial correlation. Methods of determining these quantities by astronomical or ground-based electrical measurements are described. Correlation between the theoretical predictions and the performance of actual large antenna structures is presented.

648 citations

••

[...]

TL;DR: In this paper, a high gain planar antenna with an optimized partially reflecting surface (PRS) placed in front of a waveguide aperture in a ground plane was investigated, where the antenna performance was initially related to the reflection characteristics of the PRS array following an approximate analysis.

Abstract: A high gain planar antenna has been investigated, using an optimised partially reflecting surface (PRS) placed in front of a waveguide aperture in a ground plane. The antenna performance is initially related to the reflection characteristics of the PRS array following an approximate analysis. The array geometry is optimised using an analytical formula. The optimisation results are verified using a full wave model taking into account the edge effects. The array size for maximum antenna efficiency has also been investigated.

559 citations

••

[...]

01 Aug 1959

TL;DR: In this paper, the radiansphere is defined as the boundary between the near field and the far field of a small antenna, and the power that can be intercepted by a hypothetical isotropic antenna is that which flows through the radianphere or its cross section, the "radiancircle."

Abstract: The "radiansphere" is the boundary between the near field and the far field of a small antenna. Its radius is one radianlength (?/2?), at which distance the three terms of the field are equal in magnitude. A "small" antenna is one somewhat smaller than the radiansphere, but it has a "sphere of influence" occupying the radiansphere. The power that theoretically can be intercepted by a hypothetical isotropic antenna is that which flows through the radiansphere or its cross section, the "radiancircle." From a small electric dipole, the far field of radiation is identified as a retarded magnetic field. Between two such dipoles, the far mutual impedance is that of mutual inductance, expressed in terms of space properties and the radiansphere. A small coil wound on a perfect spherical magnetic core is conceived as an ideal small antenna. Its radiation power factor is equal to the ratio of its volume over that of the radiansphere. A fraction of this ratio is obtainable in various forms of small antennas (C or L) occupying a comparable amount of space. A radiation shield, in the form of a conducting shell the size of the radiansphere, enables separate measurement of radiation resistance and loss resistance.

556 citations