Focal-Plane Arrays with Improved Scan Capabilities

This article investigates the limits of focal-plane array (FPA) technology by studying a double-reflector antenna system with wide-Angle scan capabilities. The proposed reflector configurations are analyzed in terms of effective isotropic radiated power (EIRP) maximization, minimization of the required total number of array elements for a wide-scan range, and the highest number of simultaneously active array elements of the phased-Array feed. Presented configurations have capabilities to operate in the scan range up to ± 30° in azimuth (±35 beamwidths scan) and ± 3° in elevation. It has been demonstrated how different optimizations could allow to build systems with varying performance in terms of the key operation parameters, such as array size, EIRP, and the number of active array elements. A detailed analysis is provided that demonstrates the potential applicability of this concept in future millimeter-wave (mm-wave) applications

Miniaturization of robust UHF RFID antennas for use on perishable goods and human bodies

Design guidelines for electrically small and robust UHF RFID antennas are derived for operation in complex environments, such as perishable goods (e.g. meat and milk) or human bodies. A prototype UHF RFID antenna tag with an embedded Integrated Circuit (IC) is developed and tested in a RFID system. Water and meat tissue are used as environments. The obtained range of operation appears to be very robust. Measurements show a range of 3 m for the meat case and 2.5 m for a water environment at 868 MHz

Increased operational range for implantable UHF RFID antennas

This paper discusses the main design challenges of implantable UHF RFID antennas in lossy environments. A novel cylindrical implantable antenna concept is presented. The proposed antenna shows good performance inside lossy environments, like a human body. The RFID tag is able to work in a range up to 3 m for implantation depths in the range of 1 - 2.5 cm. A basic demonstrator with RFID integrated circuit (IC) was manufactured and tested in order to prove the proposed design strategy

Reflector synthesis for wide-scanning focal plane arrays

A new complex offset double-reflector configuration for a wideband focal plane array (FPA) is presented which is optimized for Ka-band applications with a scan range of ±20° in the azimuth plane. This configuration is obtained by using a mathematical framework based on geometrical optics which allow us to optimize complex double-reflector FPAs with limited computational effort. The proposed reflector configuration maximizes the number of simultaneously active array elements of the phased-array feed and minimizes the required total number of array elements for this wide scan range. To realize an aperture efficiency of at least 80% at 30 GHz, our concept allows half of the antenna elements in the array to be active during scanning for a scan range of ±10° and at least a quarter of the array elements to be active for a scan range of ±20°. This is a major improvement as compared to the scanning capabilities of focal-plane arrays based on conventional single- and double-parabolic reflector configurations. In addition, the FPA configuration has been optimized for wideband optical true-time-delay beamforming which requires a linear phase distribution along the array elements. We obtained a phase linearity with rms error of 2.81° at 30 GHz. The experiments from the realized prototype demonstrate a good agreement between simulation and measurements and fully prove the required scanning performance over a ±20° scan range. The prototype demonstrates a high directivity up to 46 dBi at 30 GHz and 48 dBi at 40 GHz and reflector efficiency up to 83% at 30 GHz and 77% at 40 GHz

Wideband focal plane connected array

\u3cp\u3eThis paper discusses the main design challenges of wideband antenna elements which can be used in wideband focal-plane arrays and phased arrays. The impact of significant mutual coupling on the active impedance matching is presented for the case of wideband focal plane arrays (FPAs). Two novel FPA designs are presented. The array elements are based on a modified version of the well-known bow-tie antenna. The proposed array shows excellent active matching properties. It is shown that the center element of a 5×5 array, operating at a center frequency of 30 GHz, has an impedance bandwidth of 20 GHz. Moreover, a further optimized concept provides a similar bandwidth with a twice as high element density.\u3c/p\u3

Reflector synthesis for wide-scanning focal plane arrays

\u3cp\u3eA new complex offset double-reflector configuration for a wideband focal plane array (FPA) is presented which is optimized for Ka-band applications with a scan range of ±20° in the azimuth plane. This configuration is obtained by using a mathematical framework based on geometrical optics which allow us to optimize complex double-reflector FPAs with limited computational effort. The proposed reflector configuration maximizes the number of simultaneously active array elements of the phased-array feed and minimizes the required total number of array elements for this wide scan range. To realize an aperture efficiency of at least 80% at 30 GHz, our concept allows half of the antenna elements in the array to be active during scanning for a scan range of ±10° and at least a quarter of the array elements to be active for a scan range of ±20°. This is a major improvement as compared to the scanning capabilities of focal-plane arrays based on conventional single- and double-parabolic reflector configurations. In addition, the FPA configuration has been optimized for wideband optical true-time-delay beamforming which requires a linear phase distribution along the array elements. We obtained a phase linearity with rms error of 2.81° at 30 GHz. The experiments from the realized prototype demonstrate a good agreement between simulation and measurements and fully prove the required scanning performance over a ±20° scan range. The prototype demonstrates a high directivity up to 46 dBi at 30 GHz and 48 dBi at 40 GHz and reflector efficiency up to 83% at 30 GHz and 77% at 40 GHz.\u3c/p\u3

A comparative study on the parabolic and spherical FPA-fed reflector antenna

\u3cp\u3eFocal and axial fields of the parabolic and spherical quasi-optical antenna systems are analyzed. The effects of axially displaced focal plane array (FPA) in both systems were investigated. The axially displaced FPA-fed parabolic reflector can broaden the field patterns across the FPA. FPA-fed spherical reflector if carefully tuned along its paraxial line can broaden the field patterns across the FPA as well. The broadening in both systems can results in a larger reuse of the antenna elements in the FPA during beam scanning, hence a smaller FPA size can be utilized. The advantage of the FPA size reduction is that it can reduce the complexity of the FPA feeding-lines and chip-sets integration.\u3c/p\u3

Gain-maximization of FPA-fed reflectors by means of linear regression

\u3cp\u3eMutual coupling has a demonstrable impact on the embedded pattern of the focal plane array (FPA). Therefore, it is necessary to optimize the FPA complex weighting to achieve the antenna system maximum gain. A system level model based on a hybrid combination of an in-house developed PO tool, an EM tool (CST). It turns out that the mutual coupling effects on the embedded patterns of the FPA can be can be optimized through the application of a minimum least squares (LS) residual method. Subsequently, the geometry and pattern of the FPA can be further optimized to increase the efficiency of the reflector antenna system.\u3c/p\u3