Wireless Sensor Networks (WSNs) are expected to evolve significantly in the future.Wireless sensor networks typically operate at low radio frequencies and include 2.4 GHz, 868 MHz, and 433 MHz. In the future, networks are likely to use larges radio frequencies in mili meter wave because they offer more bandwidth and speed. The high bandwidth and low latency of future generation networks will enable WSNs to transmit large amounts of data quickly and reliably. Mixer applications can help to improve the efficiency and reliability of data transmission in WSNs, especially in situations where there are many nodes transmitting data simultaneously. When the frequency is high, a WSN mixer may have trouble with integration and linearity, and it will need more power.In this research, a down-conversion Gilbert cell mixer that uses a Schottky diode and a BALUN is suggested as a way to enhance the efficiency of mixer in WSN. The input frequency of the mixer is 122.5GHz, and the LO signal frequency is 120.1GHz. This mixer simulation was done with ADS 130 nm RF-CMOS. This mixer changes RF signals from 122.5 GHz to 2.4 GHz using Schottky diodes and baluns to improve RF-LO isolation (70dB), noise figure (11.0dB), and conversion gain (7.9dB). The purposed CMOS mixer possesses a 1-dB compression point in the RF bandwidth of -6.0 dBm and an IF output power of -4.9 dBm.