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A typical SO-239 UHF female, properly hooded, has an impedance bump of about 35 ohms. The length of the bump is typically 1 ⁄ 2 inch, where the female pin flares to fit over the male pin. This bump can be mitigated by using a honeycomb dielectric in the female pin area. Many VHF/UHF amateur operators use special UHF females that maintain a 50 ...
The free end of the stub is either left open-circuit, or short-circuited (as is always the case for waveguides). Neglecting transmission line losses, the input impedance of the stub is purely reactive ; either capacitive or inductive , depending on the electrical length of the stub, and on whether it is open or short circuit.
A four-point probe is used to avoid contact resistance, which can often have the same magnitude as the sheet resistance. Typically a constant current is applied to two probes, and the potential on the other two probes is measured with a high-impedance voltmeter. A geometry factor needs to be applied according to the shape of the four-point array.
Mini-UHF connector, a smaller and much newer design than the standard UHF; SMA connector A 50 ohm screwed connection. The 0.9mm centre pin is the same diameter as the centre of RG402 Coax so that connections to that cable can be made with no discontinuity, forming the pin from the coax itself. Good to 18 GHz
A Z-parameter matrix describes the behaviour of any linear electrical network that can be regarded as a black box with a number of ports.A port in this context is a pair of electrical terminals carrying equal and opposite currents into and out-of the network, and having a particular voltage between them.
The nominal impedance of the transmission line and of the amplifiers and equalisers in the transmission chain will all be the same value. [6] Nominal impedance is used, however, to characterise the transducers of an audio system, such as its microphones and loudspeakers. It is important that these are connected to a circuit capable of dealing ...
Pyramidal horn antennas for a variety of frequencies. They have flanges at the top to attach to standard waveguides. A horn antenna is used to transmit radio waves from a waveguide (a metal pipe used to carry radio waves) out into space, or collect radio waves into a waveguide for reception.
When measuring with a field strength meter it is important to use a calibrated antenna such as the standard antenna supplied with the meter. For precision measurements the antenna must be at a standard height. A value of standard height frequently employed for VHF and UHF measurements is 10 metres (33 ft).