0.14-1MHZ H FIELD ANTENNA
Small Low Frequency Transmitting or Receiving 0.14MHz to 1.0MHz Antenna
Low frequency E field antennas are usually large or have a high antenna factor (ratio of incident E field divided by the voltage developed across a load (usually 50 Ohm) = E/V. A 0.1MHz dipole would be 1500km long. Many small E field antennas are active including a high input amplifier or impedance converter or designed to be connected to a high input impedance amplifier or converter , and so are used for receiving only. Other E field measuring devices are probes providing a dc voltage output but have a low sensitivity. Many low frequency small antennas are H field antennas. Compared to other low frequency E field antennas designed to be loaded with 50 Ohms this antenna’s dimensions are very small 25.4cm (10 inches) x 20.5cm (8 inches) by 5cm (1.75 inches) deep. Because the antenna contains a resonant circuit by changing the component values the frequency range of the antenna can be modified. Although the gain is low and the Antenna Factor is high it is still a useful E field measuring antenna and can develop 1.7V/m at 1m and 2.5V/m at 0.5m at 0.33MHz and with a 75W input. The antenna is useful to measure shielding effectiveness. As an example the shielding effectiveness achieved when a black box is mounted in an aperture in a planes vertical stabilizer. Two of these antennas were used, one to develop the E field and the other to measure the induced voltage. The antenna dimension is slightly smaller than the aperture and the shielding effectiveness is the ratio of the antenna induced voltage when the antennas are measured on an open field test site divided by the induced voltage when the antenna is located in the aperture at the same distances. The dimensions of this antenna can be modified as required.
Front View of Antenna
Rear View of Antenna
The plastic fitting can be supplied with almost any dimension desired. The antenna can be made waterproof. As the antenna measures the near E field the calibration is dependent on the closeness of the source when used as an E field measuring antenna and from the antenna to the object illuminated by the antenna when used as a transmitting antenna. Calibration at 1m is provided under Calibrations. The antenna can be made with almost any dimension. The larger the dimensions the higher the gain, the lower the antenna factor.
Price: $2500US | $3200CAN (Including calibration at a specified distance).