Abstract
In this paper, a two-dimensional true time delay optical beamforming network (OBFN) has been proposed with sub partitioning capability for 3X3 phased array antenna (PAA) with operating frequency in X-Band. The architecture is based on raised cosine apodised chirp fiber Bragg grating (CFBG) and Mach-Zehnder delay interferometer (MZDI). Compared to unapodised CFBG, raised cosine apodization drastically reduces the ripple as well as sidelobes and gives a flat response in the passband of reflection spectrum. Multiwavelength optical signals with a wavelength difference of 0.3 nm are used to steer 10 GHz RF signal in elevation and azimuth direction. Further, broad angular control of beam radiation due to sub partitioned PAA is also demonstrated. The RF signal beam is steered in elevation at -62.2,-31.9, and-10.8 degrees, and in azimuth at 123.6 and 55.9 degrees. Theoretical analysis of the OBFN has been presented and validated with the experimental results. At the best of our knowledge, delay characteristics of raised cosine apodised CFBG have been theoretically explored for the first time with mathematical formulation and a comparative discussion is given with the measured data.
Highlights
T HE high demand for phased array antennas (PAA) in remote sensing applications, which can be used to tune the direction of transmission and reception of microwave signals. [1]
At the best of our knowledge, delay characteristics of raised cosine apodised chirp fiber Bragg grating (CFBG) have been theoretically explored for the first time with mathematical formulation and a comparative discussion is given with the measured data
The performance of PAA is highly affected by the characteristics of beam forming network (BFN) in terms of electromagnetic interference (EMI), frequency of operation, and phase tuning [2]
Summary
T HE high demand for phased array antennas (PAA) in remote sensing applications, which can be used to tune the direction of transmission and reception of microwave signals. [1]. In [9], multiple optical signals are individually modulated by external modulators and dedicated to photonic crystal fiber of unique length These techniques are committed to one dimensional phased array antenna where elevation control of RF beam is well represented. Two dimensional PAA with wide radiation direction shows the capability of subarray partitioning which is based on cascading of fiber Bragg gratings and commercially available variable delay lines [12]. In this technique, two CFBGs with a reflection bandwidth of 5 nm were used.But, no theoretical details regarding delay and reflection of CFBG have been discussed with the variation in wavelength. The proposed technique reduces the optical components in terms of modulators and delay elements, minimising complexity and power requirements
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