The EFS 9218 was designed because of the growing demand for a small, lightweight receiving antenna to cover the frequency range below 300 MHz. Because of the fact that dipole length is very short compared to the wavelength, symmetry has to be extremely high. So optimum symmetry was the main goal of this development. Above 300 MHz small Log.-Per.-Antennas with high gain and symmetry are a good choice.

Application

A typical application is frequency selective E-Field-Measurement outside and inside of buildings and rooms using test receivers or spectrum analyzers. The wide frequency and dynamic range cover the limits of human protection as well as the very low limits for medical implants (heart pacemaker). Field sources are AM and FM radio- and TV-stations. Furthermore, there is a variety of military and civilian radio services, not to forget CB- and amateur radio.

The antenna (conversion) factor is constant over nearly the complete frequency range giving a very natural field strength image when spectrum-analyzers are in use. In order to eliminate power supply problems and stray coupling, NiMH rechargeable batteries are built in the mounting tube. The state of the battery is monitored by a multicolor LED. After more than five hours of continuous operation, charging with the automatic charger takes about 2-4 hours. The suitable charger is the Ansmann ACS 410 or ACS 110 traveler.

The small biconical elements come with a male M4 thread, which fits into the element fixture nuts of the holder. When mounting the biconical elements care should be taken in order to avoid overtightening the threads. It is absolutely sufficient to tighten the elements with two fingers.

Options:

Opt. ACS 410: Automatic charger ACS 410 for EFS9218