A micromultiannular antenna was integrated with Mach–Zehnder modulator in a LiNbO3 electro-optical electromagnetic field sensor to measure multiple frequency response. The center response frequency of the multiannular antenna of the electromagnetic field sensor was 1.4, 2.8, and 5.2 GHz, respectively. The sensor system exhibited an average linear dynamic range of 66 dB. The minimum detectable electromagnetic field intensity of the sensor was 2.24, 3.98, and 7.07 mV/m at 1.4, 2.8, and 5.2 GHz, respectively. Furthermore, a system combined with three similar electromagnetic field sensors had function of detecting azimuth source without the effect of the rotating angle of sensor probe around its axis. The directional sensitivity pattern of the electro-optical electromagnetic field sensor system revealed uniform sensitivity. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:565–567, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25798