This example shows how to determine the Direction of Arrival (DoA) when the transmission source is an antenna located in the far-field region or by assuming that the incident signal behaves like a plane wave incident on the receive array. DoA can be denoted by two angles phi and theta in the spherical co-ordinate system. It is a common practice to use a receive antenna array to scan for any incoming signals and to calculate its angles of arrival with respect to the center of the array. The incoming signal is commonly assumed to arrive from a far-field transmission source. Proper accounting of receive array’s electromagnetic behavior is one of the key elements in determining the angles of arrival of the incident signal.

Radar cross section benchmarking example.

Will use an elementary dipole and loop antenna and analyze the wave impedance behavior of each radiator in space at a single frequency. The region of space around an antenna has been defined in a variety of ways. The most succinct description is using a 2-or 3-region model. One variation of the 2-region model uses the terms near-field and far-field to identify specific field mechanisms that are dominant. The 3-region model, splits the near-field into a transition zone, wherein a weakly radiative mechanism is at work. Other terms that have been used to describe these zones, include, quasistatic field, reactive field, non-radiative field, Fresnel region, induction zone etc. [1]. Pinning these regions down mathematically presents further challenges as observed with the variety of definitions available across different sources [1]. Understanding the regions around an antenna is critical for both an antenna engineer as well as an electromagnetic compatibility(EMC) engineer. The antenna engineer may want to perform near-field measurements and then compute the far-field pattern. To the EMC engineer, understanding the wave impedance is required for designing a shield with a particular impedance to keep interference out.

Analyzes the impedance behavior of a monopole at varying mesh resolution/sizes and at a single frequency of operation. The resistance and reactance of the monopole are plotted and compared with the theoretical results. A relative convergence curve is established for the impedance.

Analyzes the impedance behavior of a center-fed dipole antenna at varying mesh resolution/size and at a single frequency of operation. The resistance and reactance of the dipole are compared with the theoretical results. A relative convergence curve is established for the impedance.

Compares the impedance of a monopole analyzed in Antenna Toolbox™ with the measured results. The corresponding antenna was fabricated and measured at the Center for Metamaterials and Integrated Plasmonics (CMIP), Duke University. The monopole is designed for an operating frequency of 2.5 GHz.

Calculates and compares the transmit and receive manifolds for a basic half-wavelength dipole antenna array. The array manifold is a fundamental property of antenna arrays, both in transmit and receive configurations. The transmit and receive manifolds are theoretically the same due to the reciprocity theorem. This example validates this equality thus providing an important verification of the calculations performed by the Antenna Toolbox™.

Compares results published in [1] for a two-arm equiangular spiral antenna on foamclad backing(ϵr≈ 1), with those obtained using the toolbox model of the spiral antenna of the same dimensions. The spiral antennas belong to the class of frequency-independent antennas. In theory, such antennas may possess an infinite bandwidth when made infinitely large. In reality, a finite feeding region has to be established and the outer extent of the spiral antenna has to be truncated.

Studies a helical antenna designed in [2] with regard to the achieved directivity. Helical antennas were introduced in 1947 [1]. Since then, they have been widely used in certain applications such as mobile and satellite communications. Helical antennas are commonly used in an axial mode of operation which occurs when the circumference of the helix is comparable to the wavelength of operation. In this mode, the helical antenna has the maximum directivity along its axis and radiates a circularly-polarized wave.

The turnstile antenna invented in 1936 by Brown [1] is a valuable tool to create a circularly-polarized pattern (RHCP or LHCP). It is commonly used in mobile communications.

Calculation of the radiation efficiency of the antenna and antenna arrays in Antenna Toolbox. The radiation efficiency of an antenna is defined as the ratio of the outward radiated power by the antenna to the input power fed to the excitation port of the antenna. The power loss due to the port impedance mismatch is not considered here.