umbrella antenna造句

• Umbrella antennas with heights of 15 to 460 metres are in service.
• This type of antenna array is called a trideco or umbrella antenna.
• It is also possible to build an umbrella antenna with a grounded tower.
• Umbrella antennas can be built as single mast antennas or as multiple mast antennas.
• Umbrella antennas radiate omnidirectional radiation pattern.
• Thus the umbrella antenna uses the guy wires as the top-load part of the antenna.
• The umbrella antenna was used for frequencies around 30 kHz, the ring antenna for frequencies around 20 kHz.
• Many smaller anchor blocks providing foundations for smaller towers that supported the umbrella antenna are still visible in the lagoons.
• They used grounded or insulated guyed masts with umbrella antennas, or wire-spans across both valleys and fjords.
• Two further masts of the station carrying an umbrella antenna are 471 metres tall and the tallest structures in India.
• The tallest umbrella antennas are actually used by Lualualei VLF transmitter, INS Kattabomman and the CHAYKA-transmitters at Inta and Dudinka.
• Chabrier Omega Transmitter ( station E ) near Chabrier on R閡nion at used an umbrella antenna, installed on a 428-metre grounded guyed mast.
• Umbrella antennas are in common use for commercial medium-wave AM broadcasting as well as for LF and VLF transmitters for broadcasting and navigational aids.
• Umbrella antennas were invented during the wireless telegraphy era, about 1900 to 1920, and used with spark-gap transmitters on longwave bands to transmit information by Morse code.
• Small umbrella antennas were widely used with portable transmitters by military signal corps during World War I, since there was no possibility of setting up full-sized quarter-wave antennas.
• An "'umbrella antenna "'is a top-loaded mast fed at the ground end, to which a number of radial wires are connected at the top, sloping downwards.
• Eight umbrella antennas 350 metres high are in use in an array at the German VLF communications facility, operating at about 20 kHz with high radiation efficiency even though they are less than 1 / 40 wavelength high.
• Ring roads can also exist around radio masts carrying an umbrella antenna at the basements of the anchor of the wire of the umbrella antenna ( see here ), in order to get easy access to these basements.
• Ring roads can also exist around radio masts carrying an umbrella antenna at the basements of the anchor of the wire of the umbrella antenna ( see here ), in order to get easy access to these basements.
• South of INS Kattabomman, there are 2 radio masts with an umbrella antenna situated at 8.378479 N 77.744043 E and 8.375069 N 77.755834 E, which may have a height between 450 and 500 metres.