Title :
The Performance of a Fiber-Optic Link Using Unbiased Balanced Photodiodes for Antenna Array Calibration
Author :
Diehl, John F. ; Urick, Vincent J. ; McDermitt, Christopher S. ; Bucholtz, Frank ; Devgan, Preetpaul S. ; Williams, Keith J.
Author_Institution :
Naval Res. Lab., Washington, DC, USA
Abstract :
A quadrature-biased dual-output Mach-Zehnder modulator is used to drive unbiased balanced photodiodes for use in antenna array applications. The RF gain is measured as a function of frequency and photocurrent. Balanced photodiode two-tone measurements at 6 GHz are compared with those of a single photodiode to show 26-dB suppression of the second-order distortion. This results in a second-order limited spur-free dynamic-range improvement of 12 dB. The phase error introduced in unbiased photodiodes is compared to that of the biased case to demonstrate that it would have minimal effect on the performance of the antenna array system.
Keywords :
microwave antenna arrays; microwave measurement; microwave photonics; modulators; optical links; photoconductivity; photodiodes; photoemission; RF gain; antenna array calibration; balanced photodiode two-tone measurement; fiber-optic link; frequency 6 GHz; frequency function; phase error; photocurrent function; quadrature-biased dual-output Mach-Zehnder modulator; second-order distortion; second-order limited spur-free dynamic range improvement; unbiased balanced photodiode; Arrays; Calibration; Gain; Optical distortion; Photoconductivity; Photodiodes; Radio frequency; Balanced photodiodes; microwave photonics; unbiased;
Journal_Title :
Microwave Theory and Techniques, IEEE Transactions on
DOI :
10.1109/TMTT.2011.2175238
