RSSI Comparison of ESP8266 Modules

The IoT technology has been on the rise recently. Many more everyday objects and devices are now incorporated with wireless connectivity. The ESP8266 WiFi modules have been one of the wireless enabling technologies. Nowadays, there is a wide variety of ESP8266 development boards available in the market. Unfortunately, not much is known about their coverage distance. This paper aims to evaluate their coverage by means of RSSI measurement. Although not the only one, antenna is known as the key factor determining the coverage of wireless transmission. Of all common development boards, there are four models with distinctive antenna types that are chosen for comparison. Measurements are conducted in an open area. As expected, it is found that the one with dipole antenna (model D) has the strongest RSSI, followed by ceramic antenna (model C), meandered PCB antenna (model A), and meandered inverted-F PCB antenna (model B), in descending order. The RSSI at 40m is -61.38 dB,-80.59 dB, -84.51 dB, and -90.94 dB for model D, C, A, and B, respectively.