Daily Archives: March 5, 2015

Maximum Power Transfer

The power transfer from a source to it’s load is maximum when their respective impedance are complex conjugate of each other. Let and The power delivered to load is given by (1)   The condition for maximum power transfer is Therefore, and Under this condition, power delivered to load is […]

dBm Calculator

dBm is the power ratio of measured power referenced to 1 milliwatt (mW) in decibels (dB).     (1)   A change in power ratio by a factor of 10 is a 10 dB change. A change in power ratio by a factor of 2 is approximately a 3 dB […]

RF Design – Why Zo is 50 Ohms? 1 comment

The impedance of a coaxial cable depends on (1)   where, diameter of outer conductor diameter of inner conductor characteristic impedance of the cable permmitivity of free-space relative permittivity of dielectric From Eq.(1), we can conclude that it is the ratio that defines the characteristic impedance of the cable. The […]

Free-space Path Loss

Friss Equation Friss Transmission Equation gives an estimate of power received by an antenna from another antenna radiating power at some distance away. If the antenna radiates power uniformly in all directions, it is called isotropic antenna. Power() flows out from the transmit antenna in spherical wavefronts. Thus the power […]

Wireless Receiver Architectures

Various architectures of receivers has been proposed in literature, but most popular architectures among them like Heterodyne, Homodyne, Wideband-IF and Low-IF are presented here. Heterodyne Arch. Super-heterodyne Architecture was invented by Armstrong in 1917 and is the most widely used architecture in wireless transceivers so far. It is a dual […]


Duplexing Duplexing is a technique employed in communication system for bi-directional or two-way transmission of voice or data. Down link: data is carried from base station to subscriber terminal. It is also called forward link. Uplink : data is carried from subscriber terminal to base station. It is also called […]

Distortion in Feedback Amplifiers

Consider an amplifier, shown in Fig.1, whose input-output relationship under small signal conditions given by, (1)   Substituting in Eq.(1.1), (2)   To solve for , represent the transfer function of the feedback amplifier by power series as, (3)   and evaluate for , , , From Eq.(1.3), (4)   […]

60 GHz Spectrum

Around 60GHz, about 7GHz of unchannelized frequency spectrum is available for license-free wireless communication applications. It is ideal for applications that demand ultra high speed data rates over short ranges. Products, based on compound semiconductors like GaAs and InP, exits in the market to operate in this range but they […]

Second Order Intercept Point (IP2)

Second order intercept point(IP2) is a used to quantify weak non-linearity in an amplifier or RF system. It is an interpolated point where the fundamental component power curve meets the second order intermod(IMD2) component power curve. Consider a nonlinear amplifier whose input-output characteristic is represented by a 3rd order polynomial […]