Kind Of Antenna Research Articles

A time domain theoretical method for the analysis of microstrip antennas composed by slots

In this paper, a time domain method is introduced for analyzing microstrip antennas having thin slots. The present method is based on a resolution of Maxwelľs. equtions using the finite difffreence time domain method. A particular investigation has been made for taking thin slots into account, this avoids a prohibitive grid to represent the slots. Two kinds of antennas have been analyzed by this method: the slot antennas and the radiatins patch fed by a line through a slot.

A planar antenna of conductor modulating periodic structure

A novel planar leaky-wave antenna of conductor modulating periodic structure for millimeter wave application is proposed. Using the theory of two-dimensional periodic admittance surface, theoretical analysis, numerical calculation and experimental study are carried out for this kind of antenna. A planar antenna of conductor modulating periodic structure is realized in 8mm wave band. It has an aperture area of 90×90mm2. The measured performances of the antenna are good.

Effects of variations in Earth rotation on extended use of GPS orbits

SummaryTime transfer data, derived from single frequency observations of GPS satellites, have shown a unique bowing characteristic in the residuals with an amplitude which sometimes amounts to about 80 ns. Investigations attempting to explain this characteristic have so far been unsuccessful. The studies have been concerned with hardware and software effects. The hardware studies have:(a) compared data obtained with single frequency receivers with data obtained simultaneously with dual frequency receivers which eliminate the effects of the ionosphere;(b) compared data obtained with different kinds of single frequency receivers; and(c) compared data obtained simultaneously with different kinds of antennas, including one designed to minimize the effects of multipath.

Backfire antennas constructed with coaxial circular loops

The radiation characteristics of backfire antennas constructed entirely of circular loops are studied. A comparison between this type of backfire antenna and the conventional one, made of a solid reflector, reveals that the optimum dimensions of the reflector and the peripheral rim are approximately the same for both kinds of antennas. In addition, it is found that as few as six loops are sufficient to construct the optimum reflector, and almost the same number of loops are required to form the optimum peripheral rim. The new structure reduces the weight, windage, and obstruction of view which accompany solid reflectors. In addition, the new antenna lends itself to exact analytical investigation.

Disc-cylinder Argonne-Maryland gravitational radiation experiments

A new kind of antenna has been developed for gravitational radiation. It consists of a disc operating in the radial mode of circular symmetry, and search has been carried out for a scalar component. The observed ratios of coincidence rates and the observed directivity are consistent with an absence of a scalar component from the observed radiation.

Fundamental Limitations of Small Antennas

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/l <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) 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.