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For instance, if a radio wave passing a given location has a flux of 1 pW / m 2 (10 −12 Watts per square meter) and an antenna has an effective area of 12 m 2, then the antenna would deliver 12 pW of RF power to the receiver (30 microvolts RMS at 75 ohms). Since the receiving antenna is not equally sensitive to signals received from all ...
The first, a 665 foot (203 m) half-wave mast was installed at radio station WABC's 50 kW transmitter at Wayne, New Jersey in 1931. [ 4 ] [ 5 ] During the 1930s it was found that the diamond shape of the Blaw-Knox tower had an unfavorable current distribution which increased the power emitted at high angles, causing multipath fading in the ...
Tropospheric scatter, also known as troposcatter, is a method of communicating with microwave radio signals over considerable distances – often up to 500 kilometres (310 mi) and further depending on frequency of operation, equipment type, terrain, and climate factors.
The bow-tie antenna is a dipole with flaring, triangular shaped arms. The shape gives it a much wider bandwidth than an ordinary dipole. It is widely used in UHF television antennas. Cage dipole antennas in the Ukrainian UTR-2 radio telescope. The 8 m by 1.8 m diameter galvanized steel wire dipoles have a bandwidth of 8–33 MHz.
A single antenna radiating at high power (a) is replaced by a group of low-power antennas to cover the same area (b). The idea was described in a paper by Saleh et al. [2] in 1987. These antennas have recently been employed by several service providers in many areas around the United States.
A spiral antenna is a type of radio frequency antenna shaped as a spiral, [1]: 14‑2 first described in 1956. [2] Archimedean spiral antennas are the most popular, while logarithmic spiral antennas are independent of frequency: [3] the driving point impedance, radiation pattern and polarization of such antennas remain unchanged over a large bandwidth. [4]