Active Receiving Crossed Dipole Antenna HD 2 A
The main advantage of the active dipole antenna HD 2 A is its extremely large bandwidth and dynamic range. The antenna is ideal for applications requiring NVIS reception over a large frequency range (1.5 - 30 MHz).
NVIS (Near Vertical Incidence Skywave) is a radio-wave propagation method that provides usable signals in the range between groundwave and skywave distances. The majority of the NVIS antenna radiation pattern is at an extremely high angle.
NVIS provides excellent communication at distances of 300 km … 500 km whereas the typical application is within distances from approx. 50 km to 700 km. It should be noted the maximum frequencies involved is at approx. 2 MHz under poor conditions and approx. 15 MHz under very good conditions.
The usable frequencies are moving during the day time. This is caused by attenuation of the lower layer of the ionosphere for low frequencies during day time. With regard to this effect NVIS communication typically takes place between 2 MHz and 4 MHz at night and 5 MHz to 8 MHz during day light.
The very small dimensions and associated low weight makes this antenna ideal for both stationary - where space is at a premium - and transportable applications.
The system can be extended to a receiving antenna system for vertical and horizontal polarization, if necessary also subsequently, by combination with an active monopole from aas.tech STA series.
The antenna amplifier for the horizontal dipole is installed in a watertight and seawater resistant cast aluminum alloy housing, the antenna head. The antenna rods are made of glass fibre reinforced plastic fitted with stainless steel screw connections.
The cable connector is fitted to the bottom side of the antenna head's bottom flange. It is protected against the environment by means of a trumpet shaped mounting support (the funnel) which is mounted to the bottom flange of the antenna head. The opposite end of the funnel fits the size of 2" supporting pipes.
With regard to the robust construction and the use of weatherproof materials our active antennas can be used under extreme environmental conditions.
The operating voltage for the antenna is 39 Vdc. The AAN power supply series or an aas.tech Antenna Distribution System is used to feed the operating voltage to the active element via the coaxial cable.
For further information please contact
aas.tech GmbH & Co. KG