Antennas are electrical devices that will convert an electric power into a radio wave and vice versa. These are often used with radio transmitters or radio receivers. Antennas are the essential components for all the equipment that have radios. These are often used in broadcast television, communication receivers, cell phones, radio broadcasting, two way radio, radar, and satellite communication. It can also be used in some other devices such as wireless microphones, wireless computer networks, RFID tags, garage door openers, Bluetooth devices, baby monitors.
One type of this which is being used by the military is mono pole. This is consist of only one conductor like the metal rod which is mounted on the ground or in an artificial surface for conduction. An umbrella is one type of a mono pole which is used for military communications in long range. The production of these by military antenna manufacturers can be very useful for them.
An umbrella is a type which is a large wire that will transmit the antenna being used for the VLF band. It consists of mast radiator tower attached to its top with multiple wires which are extending in mast to ground, like tents and umbrellas. It is insulated in the ends. It also contains narrow bandwidth and requires counterpoise ground in low resistance and large loading coils.
Another useful type is the array. A phased array is used in military purposes especially for their jamming system and radar system. It has high gain antennas used in UHF and microwave frequencies which is electronically steerable. It consists of many dipoles with a two dimensional array. Each of the dipole will be fed through the electric phase shifter which is controlled by the computer control system.
One of the oldest type of antenna is the radio kite. It is utilized for carrying the radios in an aloft, that is higher than the practical mast. It is most often associated with a portable radios system and is also used for increasing the radio range in naval ships. The usage of this type is limited since there are some difficulties in the maintenance for its consistent height, an unpredictable wind, and some improvements for transmission, reception, and antenna.
When installing an antenna, it is important to consider its effects on the ground. Factors to consider are height, electrical properties, permittivity, and the conductivity. Particularly, in mono pole antennas, grounds serve as a return connection of the current and this is the reason for the effects.
For those that have a low frequency to high frequency, the grounds will behave as lossy dialectrics. Thus, these are being characterized by conductivity and permittivity. For lower frequencies, it will act as the good conductor.
If the frequency is between 3 to 30 megahertz, a very large portion of energy from the horizontally polarized antennas will reflect on it. While the vertically polarized one will not be well reflected except for the grazing incidence. However, the reflection of grazing angles is in phase with direct waves.
A net quality of a reflection is dependent to surface topography. If irregularities of a surface which are smaller than the wavelength, specular reflection is there. But if these are not big, the reflection is shifted by a random phase.
One type of this which is being used by the military is mono pole. This is consist of only one conductor like the metal rod which is mounted on the ground or in an artificial surface for conduction. An umbrella is one type of a mono pole which is used for military communications in long range. The production of these by military antenna manufacturers can be very useful for them.
An umbrella is a type which is a large wire that will transmit the antenna being used for the VLF band. It consists of mast radiator tower attached to its top with multiple wires which are extending in mast to ground, like tents and umbrellas. It is insulated in the ends. It also contains narrow bandwidth and requires counterpoise ground in low resistance and large loading coils.
Another useful type is the array. A phased array is used in military purposes especially for their jamming system and radar system. It has high gain antennas used in UHF and microwave frequencies which is electronically steerable. It consists of many dipoles with a two dimensional array. Each of the dipole will be fed through the electric phase shifter which is controlled by the computer control system.
One of the oldest type of antenna is the radio kite. It is utilized for carrying the radios in an aloft, that is higher than the practical mast. It is most often associated with a portable radios system and is also used for increasing the radio range in naval ships. The usage of this type is limited since there are some difficulties in the maintenance for its consistent height, an unpredictable wind, and some improvements for transmission, reception, and antenna.
When installing an antenna, it is important to consider its effects on the ground. Factors to consider are height, electrical properties, permittivity, and the conductivity. Particularly, in mono pole antennas, grounds serve as a return connection of the current and this is the reason for the effects.
For those that have a low frequency to high frequency, the grounds will behave as lossy dialectrics. Thus, these are being characterized by conductivity and permittivity. For lower frequencies, it will act as the good conductor.
If the frequency is between 3 to 30 megahertz, a very large portion of energy from the horizontally polarized antennas will reflect on it. While the vertically polarized one will not be well reflected except for the grazing incidence. However, the reflection of grazing angles is in phase with direct waves.
A net quality of a reflection is dependent to surface topography. If irregularities of a surface which are smaller than the wavelength, specular reflection is there. But if these are not big, the reflection is shifted by a random phase.
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