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In same-band repeaters, isolation between transmitter and receiver can be created by using a single antenna and a device called a duplexer. The device is a tuned filter connected to the antenna. In this example, consider a type of device called a band-pass duplexer. It allows, or passes, a band, (or a narrow range,) of frequencies.
In comparison, the lowest channel in the UHF band, Channel 14, is on 470 MHz, a wavelength of 64 cm, or a dipole length of only 32 cm. A powerful VHF antenna using the log-periodic design might be as long as 3 m, while a UHF Yagi antenna with similar gain is often found placed in front of it, occupying perhaps 1 m.
It is difficult to design a single antenna to receive such a wide wavelength range, and there is an octave gap from 216 to 470 MHz between the VHF and UHF frequencies. So traditionally, separate antennas (outdoor antennas with separate sets of elements on a single support boom) have been used to receive the VHF and UHF channels. [6]
Ultra high frequency (UHF) is the ITU designation [1] [2] for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter (one decimeter).
An antenna array (or array antenna) is a set of multiple connected antennas which work together as a single antenna, to transmit or receive radio waves. [1]: p.149 [2] The individual antennas (called elements) are usually connected to a single receiver or transmitter by feedlines that feed the power to the elements in a specific phase relationship.
UHF: 225 TO 399.975 MHz Estimated Range: 5–20 km (3-12 mi) Dependent on conditions. This is the approximate range when not connected to a repeater or a network. Power Output: 2W to 10W Power Source: BA-5590/U non-rechargeable or BB-2590/U and UBI-2590 rechargeable batteries. Antenna: These units use the MPMP100X4 antenna (NSN 5985-01-184-0035).
The dish antenna occupies the high frequencies (typically 950 to 1450 MHz), and the TV antenna uses lower television channel frequencies (typically 50 to 870 MHz). In addition, the satellite also gets a DC to low frequency band to power the dish's block converter and select the dish antenna polarization (e.g., voltage signaling or DiSEqC ).
Standard repeaters require either the use of two antennas (one each for transmitter and receiver) or a duplexer to isolate the transmit and receive signals over a single antenna. The duplexer is a device which prevents the repeater's high-power transmitter (on the output frequency) from drowning out the users' signal on the repeater receiver ...