Mekeng, R., and I. . . Fitri. “Design And Analysis Of Antenna Microstrip Patch Pi Slot Array Four Elements With Proximity Coupling Method For Multi Wide Band Characteristics: ”. Jurnal Mantik, vol. 5, no. 3, Oct. 2021, pp. 1504-13, https://iocscience.org/ejournal/index.php/mantik/article/view/1299.