Max power for E220 30dB module

Hi. First of all thank you for all your great work. I use your tutorials to build a comunication between some vineyards. In each, it is an arduino nano connected to a E220-900T30D and to a relé. Arduino is powered by a 6V battery, by VIN pin; e220 module is powered by 5V pin of arduino. I saw, during message is send, that voltage on 5V pin drops for a moment. This is because of massive current consumption of e220 module during transmission. How i can prevent this voltage drop to improve maximum transmission-power of e220 module? Maybe I can power e220 module directly from battery, with a dc-dc step-down voltage divider? Or maybe placing a super-capacitor (0.1F, 5.5V) between vcc and gnd of e220 module? My goal is to offer constant 5.5V power to e220 module.