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A radio transmitter design has to meet certain requirements. These include the frequency of operation, the type of modulation, the stability and purity of the resulting signal, the efficiency of power use, and the power level required to meet the system design objectives. [1]
4×4 array of 2.4 GHz patch antenna elements Patch antenna gain pattern. A patch antenna is a type of antenna with a low profile, usually consisting of a printed circuit board. It consists of a planar rectangular or circular sheet or "patch" of metal, mounted over a larger sheet of metal called a ground plane.
Schematic of an AGC used in the analog telephone network; the feedback from output level to gain is effected via a Vactrol resistive opto-isolator.. Automatic gain control (AGC) is a closed-loop feedback regulating circuit in an amplifier or chain of amplifiers, the purpose of which is to maintain a suitable signal amplitude at its output, despite variation of the signal amplitude at the input.
Paul Voigt patented a negative feedback amplifier in January 1924, though his theory lacked detail. [4] Harold Stephen Black independently invented the negative-feedback amplifier while he was a passenger on the Lackawanna Ferry (from Hoboken Terminal to Manhattan) on his way to work at Bell Laboratories (located in Manhattan instead of New Jersey in 1927) on August 2, 1927 [5] (US Patent ...
The loss in that feed line is 3.2 dB at 1 GHz; approximately 5 dB at the GPS frequency (1.575 42 GHz). This feed line loss can be avoided by placing an LNA at the antenna, which supplies enough gain to offset the loss. An LNA is a key component at the front-end of a radio receiver circuit to help reduce unwanted noise in particular.
Shortwave receivers: 1.6 MHz, [11] 1.6–3.0 MHz, [1] 4.3 MHz (for 40–50 MHz-only receivers). [11] In double-conversion superheterodyne receivers, a first intermediate frequency of 3.0 MHz is sometimes combined with a second IF of 465 kHz. [1] Analogue television receivers using system M: 41.25 MHz (audio) and 45.75 MHz (video).
Typical feeder loops are 1 / 8 to 1 / 5 the size of the antenna's main loop, which gives transform ratios of 64:1 to 25:1, respectively. Adjusting the proximity and angle of the feeder loop to the main loop, and distorting the feeder's shape, both make small-to-moderate changes to the transform ratio, and allows for fine ...
The FDA gain calculated at DC does not apply at higher frequencies. To a first approximation, the gain of a typical FDA is inversely proportional to frequency. This means that an FDA is characterized by its gain-bandwidth product. For example, an FDA with a gain bandwidth product of 1 MHz would have a gain of 5 at 200 kHz, and a gain of 1 at 1 MHz.