Radiation Pattern Of Antenna Array Research Articles

Null steering by real-weight control-a method of decoupling the weights

A method for independent steering of each null in the radiation pattern of a linear antenna array using real weight control is introduced. The method depends on decoupling the weights such that each real weight is associated with a given null. It has the capability of tracking the direction of jammers by changing only the weight corresponding to each jammer. Phase shifters are used solely to steer the main beam in the direction of the desired signal. The price for using this method is that the number of steerable nulls is equal to or less than half of the total number of array elements. >

The possibility of parametric control by means of the directional radiation patterns of antenna arrays

The possibility of parametric control by means of the directional radiation patterns of antenna arrays

An investigation of the design of a log-periodic dipole array with low side-lobe levels for broadcast applications

The problem of cochannel interference is addressed. The ability of the Numerical Electromagnetics Code (NEC2) computer program to predict the radiation pattern of an antenna array on a mast is investigated. The evaluation and validation of NEC2 is undertaken by the comparison of measured and computed radiation patterns of log-periodic dipole antenna arrays. Emphasis is placed on the correspondence of the side-lobe levels -30 to -40 dB down from the main lobe. This is important in the synthesis of an array with predictable null positions and depths.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Customized pattern applications of the FM CBR antenna

The CBR (cavity-backed radiator) panel element has been proven to have high versatility and predictability in multiplexed FM antenna array radiation patterns. Special customized patterns with deep nulls (notch patterns) are discussed. The desired patterns can be accomplished by skewing the corresponding CBR elements off center by an appropriate amount and by adjusting the electrical phase of the corresponding feedline in order to obtain the necessary phase difference between the adjacent cavities.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Effect CF Power Lines on AM Radio Broadcast Radiation Patteins

A power transmission line can create distortion of the radiation pattern of a nearby AM radio broadcast antenna array. Techniques have been developed to study this effect and remedial measures are proposed to minimize it. Three types of tower stubs have been tested. These consist of lengths of wire connected to the tower near the top and terminated near ground with capacitors that are tuned to the desired frequency. The effectiveness varies with the complexity of the stub. Two types of skywire stubs were also tested. These were difficult to tune, difficult to test and perhaps not as effective as tower stubs. Isolating the skywire fran transmission towers remains the least expensive but least predictable remedial measure. A systematic masurement technique for verifying the effects of remedial measures is presented.

Smoothing of Omnidirectional Horizontal Radiation Patterns of tfd TV Panel Antenna Arrays With Progressive Current Phase Shift Feeding

This paper shows how the mechanical panel displacement technique can be used effectively in order to smooth out omnidirectional patterns of TFD TV panel antenna arroys fed by progressive phase shift currents (Fig. la).

A study of the effect of buildings on the radiation patterns of simple antenna arrays

The effect of a building on the radiation pattern of a two-element broadside array and an endfire array is studied by the moment method and the unimoment method. Buildings are made in the similitude of square and rectangular conducting or dielectric cylinders of infinite length.

Partial radiation patterns of phased antenna arrays

Partial radiation patterns of phased antenna arrays

Linear antenna arrays with broadened nulls

It is shown that a null in the radiation pattern of a linear antenna array can be broadened into a null sector by the use of suitable forms of amplitude taper. For a uniformly spaced array, binomial taper coefficients with alternate positive and negative signs produce a maximally-flat null broadening. Null slewing by means of phase taper and null broadening by means of amplitude taper can be regarded as two independent operations.

A Computer Program for Calculating the Radiation Pattern of a General Antenna Array

A Computer Program for Calculating the Radiation Pattern of a General Antenna Array

FM effect on the radiation patterns of high-gain antenna arrays

FM effect on the radiation patterns of high-gain antenna arrays

The radiation patterns of antenna arrays consisting of dipoles coupled to a two-wire transmission line

In this paper the radiation patterns of antenna arrays consisting of dipoles coupled electromagnetically to a two-wire transmission line are reported. The numerical calculation was made on an IBM 650 computer.

A GENERAL DISTRIBUTION FUNCTION OF NULLS ON THE UNIT CIRCLE OF LINEAR ANTENNA ARRAYS

The present author suggests a new distribution function for the roots of the complex polynomial corresponding to the nulls of the radiation pattern of a linear antenna array on the unit circle in a complex plane which is more general than the one suggested by the same author in a previous paper. The new distribution function is of the form ψ K =ψ 0 {1+ξK ((ln(ψ m /ψ 0 -1)-lnξ)/(ln m)) }. When ψ 0 and ξ are chosen properly, the suggested distribution includes the following distributions or arrays as special cases: (1) the uniform end-fire arrays; (2) the uniform broadside arrays; (3) the Schelkunoff's distribution in the range of ψ; (4) the Dolph-Tchebyscheff's distribution for number of elements not greater then seven. But the suggested distribution has the advantage of improving all of them, especially for the suppression of side-lobes near-by the main beam which is very important in certain practical applications.Moreover, since the primary patterns of many types of radiating elements fall off with increasing angle from the main maximum so that the wide-angle lobes would be at a lower level than those close to the main beam, it is necessary to design an array pattern in such a way so that the side-lobes should increase in magnetude with increase in angle from the position of the main beam in order to achieve an over-all pattern with side-lobes all equal or approximately equal in magnitude which is useful in many practical applications. Neither Schelkunoff's distribution in the range of ψ nor Dolph-Tchebyscheff's distribution meets this requirement but the suggested distribution does.In this paper, explicit expressions for the relative antenna currents have been put in closed forms convenient for calculation and semigraphical method has been used for all the pattern calculations.

Parasitic excitation of circular antenna arrays

A method of calculating the radiation pattern of a circular antenna array of parallel monopoles or dipoles using symmetrical components is presented. The results obtained when only one element of the array is excited are not particularly good. However, if an additional element is added at the center of the array a fairly good directional pattern results. The sidelobe level is dependent upon the tuning of this central element, and a graphical analysis is given which optimizes this tuning. Calculated and measured patterns are shown and compared. Sidelobe levels of 15 db, and a beamwidth of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">78\deg</tex> are typical. The principal advantage of this antenna lies in the fact that the pointing of the beam can be changed by simply changing the element that is excited.

Charts for the Determination of the Root-Mean-Square Value of the Horizontal Radiation Pattern of Two-Element Broadcast Antenna Arrays

A set of two charts is presented from which the root-mean-square value of the horizontal radiation patterns of two-element antenna arrays may be determined guickly without calculation. These charts are based upon the formula E rms =E 1 VI + M2+ 2M Jo( 2irS/ 360) * cos 4. Observations on the fact that the root-mean-square value is independent of phasing for 138 degrees spacing are made.