We present Giant Metrewave Radio Telescope ( GMRT ) 323 MHz radio continuum observations toward 13 radio-loud quasars at z > 5 , sampling the low-frequency synchrotron emission from these objects .
Among the 12 targets successfully observed , we detected 10 above 4 \sigma significance , while 2 remain undetected .
All of the detected sources appear as point sources .
Combined with previous radio continuum detections from the literature , 9 quasars have power-law spectral energy distributions throughout the radio range ; for some the flux density drops with increasing frequency while it increases for others .
Two of these sources appear to have spectral turnover .
For the power-law-like sources , the power-law indices have a positive range between 0.18 and 0.67 and a negative values between -0.90 and -0.27 .
For the turnover sources , the radio peaks around \sim 1 and \sim 10 GHz in the rest frame , the optically thin indices are -0.58 and -0.90 , and the optically thick indices are 0.50 and 1.20 .
A magnetic field and spectral age analysis of SDSS J114657.59+403708.6 at z = 5.01 may indicate that the turnover is not caused by synchrotron self-absorption , but rather by free-free absorption by the high-density medium in the nuclear region .
Alternatively , the apparent turnover may be an artifact of source variability .
Finally , we calculated the radio loudness R _ { 2500 \AA } for our sample , which spans a very wide range from 12 ^ { +13 } _ { -13 } to 4982 ^ { +279 } _ { -254 } .