The EFS 9221 is an active, symmetrical biconical antenna with a wide frequency range of more than 5 decades and a remarkable flat frequency response. In contrast to the frequently used unsymmetrical vertical monopole or rod antennas the EFS 9221 allows precise fieldstrength measurements, thanks to a very high common mode rejection. Because of its small dimensions and a built in rechargeable NiMH battery the EFS 9221 is a perfect choice for portable applications. The sensitivity can be improved by approx. 11 dB using the optional BBUK 9139 M4 biconical elements. Frequency range: 9 kHz – 1 GHz.