Fresnel Zone Plate Lens Antenna Research Articles

Additively Manufactured Millimeter-Wave Dual-Band Single-Polarization Shared Aperture Fresnel Zone Plate Metalens Antenna

Fresnel zone plate (FZP) lens antenna, consisting of a set of alternative transparent and opaque concentric rings arranged on curvilinear or flat surfaces, have been widely used in various fields for sensing and communications. Nevertheless, the state-of-art FZP lens antennas are limited to a single band due to the frequency-dependent feature, which hinders their use in multi-band applications. In this work, a shared aperture dual-band FZP metalens antenna is proposed by merging two single-band FZP metalens antenna operating at distinct frequency bands seamlessly into one. Instead of using conventional metallic conductors, double-screen metagrids are devised in this work to form the concentric rings. Because the metagrids show distinct transmission/reflection properties at different frequencies, the performance of one set of concentric rings operating at the one band will not be affected by the other operating at the different band. In addition, to compensate for the phase shift introduced by the metagrids, an additional dielectric ring layer is added atop the FZP taking advantage of additive manufacturing. Thus, the radiation performance of the dual-band FZP lens antenna is comparable to that of each single FZP metalens antenna. For proof-of-concept, an antenna prototype operating at the dual band, 75 and 120 GHz with a frequency ratio of 1.6, is fabricated using an integrated additively manufactured electronics (AME) technique. The measured peak gains of 20.3 and 21.9 dBi are achieved at 75 and 120 GHz, respectively.

270-GHz LTCC-Integrated High Gain Cavity-Backed Fresnel Zone Plate Lens Antenna

A compact cavity-backed Fresnel zone plate (FZP) lens antenna, integrated in low-temperature co-fired ceramic (LTCC) is proposed to achieve high gain at 270 GHz band. The gain is enhanced by using the back cavity formed by a via sidewall and a ground plane. A compact feeding transition is proposed to realize the broadband impedance matching in order to reduce the considerably large reflection at high permittivity substrate-air interface when the antenna is directly fed by an external air-filled waveguide. The measured results show that the proposed cavity-backed FZP lens antenna achieves a boresight gain of 20.8 dBi at 270 GHz and a 3-dB gain bandwidth of 9.1 GHz (266.2-275.3 GHz).

Focusing Properties of Fresnel Zone Plate Lens Antennas in the Near-Field Region

Some focusing properties of Fresnel zone plate (FZP) lens antennas in the near-field region are presented at the ka-band. Simulated and measured results of the FZP antenna show displacement of the maximum intensity of the electric field along the axial direction from the focal point toward the antenna aperture. This displacement increases as the antenna's focal length increases. In addition, the focused beam scanning of the FZP lens antennas in the radiation near-field is examined.

Reference Phase in Diffractive Lens Antennas: A Review

We review a free parameter in the design of Fresnel zone plate lens antennas. Historically, zone plate antennas have been designed with a specific choice for this parameter, which can be taken as a type of phase reference. Two methods of interpreting the parameter have been identified, either in terms of a reference radius or equivalently a reference phase. Here, for simplicity, we treat this variable parameter as a reference phase. Importantly, the reference phase can be chosen to have non-standard values which have been shown to improve important aspects of antenna performance and to add a new functionality to zone plate antennas.

Terahertz Harmonic Operation of Microwave Fresnel Zone Plate Lens and Antenna: Frequency Filtering and Space Resolution Properties

This paper examines the binary Fresnel zone plate (FZP) lens frequency-harmonic and space-resolution focusing, and its application as a FZP lens antenna. A microwave FZP lens antenna (FZPA) radiates both at design (90 GHz) and terahertz (THz) odd harmonic frequencies. Frequency and space domain antenna operation are studied analytically by use of the vector diffraction integral applied to a realistic printed FZPA. It is found that all harmonic gain peaks are roughly identical in form, bandwidth, and top values. At each harmonic frequency, the FZPA has a beamwidth that closely follows the Rayleigh resolution criterion. If the lens/antenna resolution is of prime importance and the small aperture efficiency is a secondary problem the microwave-design FZP lens antenna can be of great use at much higher terahertz frequencies. Important feature of the microwave FZP lens is its broader-zone construction compared to the equal in resolution terahertz-design FZP lens. Thus, unique and expensive microtechnology for the microwave FZP lens fabrication is not required. High-order harmonic operation of the FZP lens or lens antenna could find space resolution and frequency filtering applications in the terahertz and optical metrology, imaging tomography, short-range communications, spectral analysis, synchrotron facilities, and so on.

Conical Double-Dielectric Fresnel Zone Lens and Antenna

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A conical double-dielectric phase-reversal Fresnel-zone plate (FZP) lens is introduced. We present the lens design equations as functions of cone opening angle. As an example, the phase-reversal lens has been applied to four millimeter-wave antennas with different lens opening semi-angles: 45<formula formulatype="inline"><tex>$^{\circ}$</tex></formula>, 60<formula formulatype="inline"> <tex>$^{\circ}$</tex></formula>, and 75<formula formulatype="inline"><tex>$^{\circ}$</tex> </formula> (conical lenses) and 90<formula formulatype="inline"><tex>$^{\circ}$</tex> </formula> (plane lens). The radiation characteristics of these antennas have been calculated and contrasted one-to-another, and to those with the same semi-angles and linear dimensions binary (half-open) FZP lens antennas. The double-dielectric FZP conical arrangement can serve as a conical antenna lens and a radome simultaneously. </para>

Array of hexagonal Fresnel zone plate lens antennas

An array of overlapping single-zone hexagonal Fresnel zone plate lens antennas was designed and tested at 30 GHz. By arraying smaller-diameter lenses, a significantly lower overall profile can be achieved compared to a single lens of equivalent diameter. These arrays can also find use in spatial power combining or in imaging applications.

Curvilinear Fresnel-Zone Plate Lens Antenna: Vector Radiation Theory

A generalized vector diffraction theory of the half-open curvilinear Fresnel zone plate (FZP) tens antenna that is valid for any lens profile shape is presented. It is an extension to the vector Kirchhoff diffraction theory for the plane half-open FZP lens antenna and is based on the conical-segment lens profile approximation. An equation for the electric far-field vector is derived from which follow the expressions for the co- and cross-polarization radiation patterns and directive gain. The proposed theory is utilized for a numerical analysis and comparison of 140-GHz curvilinear half-open FZP lens antennas grouped in two distinct sets: (a) Set I: antennas with different in shape FZP lenses (plane, conical, parabolic and spherical) having the same number of zones. All eurvilinear FZP antenna lenses are designed for similar gain, co- and cross-polarization performance and bandwidth, regardless of the lens-profile. (b) Set II: antennas with different in shape FZP lenses and different number of zones. Since this affects gain, polarization and bandwidth performance, to make the characteristics of these FZP lens antennas practically equal to those of Set I, antenna feeds with different gain patterns have been used.

Theoretical and Experimental Studies of the Fresnel Zone Plate Lens Antenna†

ABSTRACT A family of multi-layer Fresnel Zone Plate (FZP) lenses is proposed to enhance the aperture efficiency, and suppress the backward radiation. In order to analyze the field distribution in the focal region of the lens, an improved full-wave analysis based on vector Hankel transform and spectral domain immittance matrix is developed. Various fundamental properties of FZP lens are given, these properties will provide guidance for designing a FZP lens antenna.