In this paper, we will investigate, design, and construction of a compact ultrawideband antenna that has been amplified utilizing an active amplifier circuit to be used in microwave imaging. There are some principal features regarding the proposed antenna: simple design, compact and small dimensions, and bandwidth. We utilize the Monopole antenna powered by Coplanar Waveguide CPW to diagnose strokes and brain tumors in a heterogeneous brain environment. The wide bandwidth of the designed antenna has been achieved by producing a slot on the ground, forming a non-uniform structure, and applying a split-ring resonator. The size of the designed compact antenna is equal to 0.1𝜆×0.08𝜆×0.005𝜆, which is placed on a substrate of FR-4 material and has a full connection with the biological tissue of the head. The outcomes of simulations and construction confirm that the designed antenna has impedance bandwidth specifications of 1 to 6 GHz (10 dB), efficiency more than 90%, specific absorption rate 0.007 W/Kg, fidelity factor higher than 70%, near field directivity more than 93% and homogeneity more than 90% of the field in the center of the phantom. The proposed active circuits also have impedance bandwidth specifications of 1 to 6 GHz, a gain of more than 10 dB, and a noise of less than 3 dB.