Design of a Polarization Rotating SIW-Based Reflector for Polarimetric Radar Application

Abstract

Polarimetric radar systems are beneficial to identifying and classifying targets but require multiple transmit or receive channels with different polarizations. This leads to a high hardware effort and thus higher costs. To use a single, linear polarized radar sensor as a polarimetric system, a frequencydependent, polarization rotating reflector which can be placed in front of the radar antenna is presented. The reflector is based on a frequency selective surface (FSS) consisting of slot-excited substrate integrated waveguide (SIW) resonators. Resonator modes are analyzed and an equivalent circuit diagram to describe the filter functionality is developed. For using the described FSS as reflective structure, the design focuses on 45 • oblique incidence. Different field vectors for normal and oblique incident angles are considered and different cavity modes for these cases are analyzed. An undesired mode is suppressed by an additional plated through via hole and slot impedances are matched. Reflector designs for normal and oblique incident angles are presented for 15 GHz (K u-band) and afterward adapted to 35 GHz (K a-band). The frequency band of operation with 12% fractional bandwidth is divided into two 4.5% subbands which allows a frequency-dependent polarization rotation of a linear polarized electromagnetic wave. Investigations on the fabrication accuracies are presented and reflectors for both bands are manufactured. Measurements are performed with a vector network analyzer and results fit well to the simulated curves. In the band of polarization rotation reflection, the matching is better than −13 dB and dielectric losses of less than 1 dB are achieved.

Design Investigation of a Broadband Polarization Rotator Using SIW Technology with T-Shaped Slots

“…The perturbed square SIW cavity using different shapes of the corner cuts has been studied in [21]. Using the slanted cavity edges, two resonate frequencies of TE120 and TE210, are coupled, and so, their resonant frequencies are separated [7,21], leading to obtaining wide bandwidth. In our case, the SIW cavity is disturbed by two symmetrical corner cuts along its diameter.…”

“…Frequency selective surfaces (FSSs) are periodic structures which can be used to spatially filter electromagnetic (EM) waves [1,2]. These are widely used in the microwave, millimeter-wave, and sub-millimeter-wave regions and have found a variety of applications in reflector antennas, radar radomes, and also other offers including polarimetric imaging and remote sensing [3][4][5][6][7]. In recent years, FSSs are used for designing planar polarizers such as polarization rotator to select an EM wave with a prescribed frequency and polarization state and rotate its polarization by a defined angle [6][7][8][9][10][11][12][13][14][15], especially a rotation of 90° is realized to convert a vertically polarized wave to a horizontal wave.…”

“…Recently, cavity-based structures made of low-profile resonators have been adopted to design of FSSs based on the SIW technology [5][6][7][8][9][10][11][12][13][14][15][16]. SIW FSS structure provides a few features including low insertion loss, high Q-factor, high selectivity, and sharp roll-off at the passband edges with low cost and eases to fabricate.…”

Design of a transmissive dual-frequency polarization rotator for linearly polarized electromagnetic wave

“…Polarization converters can generally be categorized into linear polarization converters [9][10][11][12], linear-circular polarization converters [13][14][15][16], and circularly polarized converters [17][18][19][20], depending on their applications. At the same time, the polarization rotator is also a type of polarization converter.…”

Synthesis of a polarisation‐rotating surface with reflective filtering response based on orthogonally inserted coupled slot‐lines

“…Another design concept is utilising multilayer metal layers and substrates to obtain highorder filtering responses [24]. Additionally, the PRSs based on substrate integrated waveguide (SIW) cavity resonators have been reported in [25,26], which have the advantages of low-loss and high-Q filtering, thus sharpening roll-off skirts at the passband edges. Polarisation rotators implemented by graphene metasurfaces have also been reported to operate in THz band [27,28].…”