Dual-Band, Orthogonally-Polarized LP-to-CP Converter for SatCom Applications

Abstract

A systematic design of dual-band, orthogonallypolarized linear-to-circular polarization (LP-to-CP) converters is proposed. This class of polarization converters can transform linearly-polarized waves into right-and left-hand circularlypolarized (RHCP and LHCP) waves in two separate non-adjacent frequency bands. The reported polarizer is made of three cascaded bianisotropic sheet admittances, spaced by two isotropic dielectric slabs. The electromagnetic problem is studied by means of impedance boundary conditions. A transmission-matrix analysis of periodically-loaded transmission-lines is employed in design. An analytic model is developed and closed-form expressions are derived for the frequency response of each sheet admittance. This method avoids the use of multi-parameter optimization procedures. An example of a dual-band, orthogonally-polarized LP-to-CP converter is proposed for satellite communication applications in the K/Ka-band. The polarizer separately performs LP-to-LHCP and LP-to-RHCP conversions over the transmitting and receiving channels of the K/Ka-band. The design is validated with a prototype. Under normal incidence, the polarizer exhibits axial ratios (ARs) lower than 3 dB over the 18-22.2 GHz (∼21%) and 28.7-30.4 GHz (∼6%) bands. The total transmission is above-1 dB within the same two bands. The performance is stable for scanning angles up to ±45 •. For a 45 • angle of incidence, the AR is lower than 3 dB in the bands 17-22 GHz (∼25.6%) and 28.6-30 GHz (∼4.7%) with a total transmission higher than-1.2 dB.

Equidispersive Dual-Mode Long Slot Arrays

“…Furthermore, physical structures, that may realize reactive sheets, rely on metallic patterns printed on grounded dielectric slabs, as done in [17], [18]. These structures resemble anisotropic metawaveguides and can be designed by following the approach outlined in [20]- [22]. Basically, independent circuit models are employed to reconstruct the desired surface reactance, according to the E-field polarization.…”

“…Since surface impedances are here demanded to be inductive and capacitive for yand xpolarized E-fields, respectively, their physical realization can be approached separately. Owing to their geometrical shape, meandered Jerusalem crosses [20], [21] may represent a valid candidate as meta-waveguide's unit cell. Their design can be carried out by following the approach used in [22].…”

Fully Metallic Dual-Band Linear-to-Circular Polarizer for K/Ka-band

“…Moreover, a wide-band multilayer single-band polarizer based on split-rings bisected by strips was proposed in [29]. Dual-band polarizers with orthogonal handedness of the polarization in the two bands have been presented [30], [31] and recently proposed for broadband satcom services [32]- [35]. The aforementioned designs require a mechanical support structure (usually a substrate), which is a source of losses at millimeter-wave frequencies.…”

Passive FSS based polarization converter integrated microstrip antenna

“…Asymmetric unit cells are employed for CP generation 2–8 . For obtaining broadband LP to CP conversion, complicated structures like arrays of split‐ring resonators bisected by metallic strips and rectangular metallic patches, 9 right‐angled FSSs, 10 multilayer FSS, 11–14 meander‐line metasurface, 15 and centro‐symmetric dual loop structures 16 have been employed which revolve around structure optimization, cascading of multiple layers and topology optimization. KOH etched cross and split ring slot, single and double layered PC structures 17 suffer deterioration in axial ratio performance with a decrease in conductivity due to the formation of charge traps on the interface.…”