Questions & Answers on RF Basics

Nov 29, 2017

When an AC current is applied to a conductor, the current concentrates near the surface of the conductor and its strength decreases as you go towards the center of the conductor. The depth till which current flows in a conductor is called as Skin Depth. The figure shows the cross section of a cylindrical conductor, the intensity of the red color represents the intensity of the current in a cylindr...read more

What is dBi?

Why is the 60 GHz Band not good for long-range communications?

Nov 29, 2016

Antenna gain is measured in decibels. It is the ratio between the gain of the antenna compared to the gain of an isotropic antenna. An isotropic antenna is a theoretical antenna which radiates power uniformly in all directions. When we calculate the gain of an antenna and compare it to an isotropic antenna the unit of the gain is dBi (i stands for Isotropic antenna). An Isotropic antenna has a 0 d...read more

RF Basics RF Propagation

Aug 17, 2017

At 60 GHz, Oxygen molecules in the atmosphere interact with the RF signals to cause significant attenuation. Due to this attenuation the 60 GHz band is not a good frequency to use for long-range radar or communication applications. At 60 GHz O2 can cause an attenuation of up to 10 dB/km.As we go higher up in frequency gasses in the atmosphere start to react with RF Signals causing attenuation. As ...read more

ISM Frequency Bands

What are Near Field and Far Field Regions of an Antenna?

Apr 24, 2018

ISM stands for Industrial, Scientific and Medical. The ITU (International Telecommunication Union) had originally reserved a portion of the RF spectrum globally for industrial, scientific and medical applications.The use case was followed initially, however over the years, the use of the ISM Bands become more widespread for short-range, low power wireless communications systems likecordless phones...read more

May 22, 2018

When a signal from a transmitter is applied to an antenna, it sends out electromagnetic waves in to free space. The EM field characteristics vary as a function of distance from the antenna. They are broadly divided into two regions, the near-field region, and the far field region.The Near Field Region is the region right next to the antenna. It is defined by the following equation:In this region, ...read more

What is EIRP?

May 22, 2018

Effective Isotropic Radiated Power or Equivalent Isotropically Radiated Power (EIRP) is a measurement of radiated output power from an ideal isotropic antenna in a single direction.An isotropic antenna is meant to distribute power equally in all directions – When we channel that power into a single direction and calculate the power it is known as EIRP. It will be the maximum power emitted by the a...read more

What is IP3?

What is the difference between EIRP and ERP?

Anjali lahoti

Dec 8, 2017

Third order intercept point is an hypothetical point where the power of third order components will reach to the same level of fundamental component's power.If one draws the power input versus power output, they will observe the different frequency components having different slopes (fig1).So, Third order intercept point is an ideal point as once the device reaches to 1 dB compression point the tw...read more

What is the difference between dBi and dBd?

May 22, 2018

EIRP is the Effective isotropic radiated power is the total power radiated by a hypothetical isotropic antenna in a single direction. It gives the signal strength in the direction of the antenna's strongest beam.ERP is Effective Radiated Poweris the total power radiated by an actual antenna relative to a half-wave dipole rather than a theoretical isotropic antenna. A half-wave dipole has a gain of...read more

Nov 29, 2016

Jul 23, 2018

An amplifier provides a constant gain for a specific frequency range. If we represent the Input power Vs Output power of an amplifier on a graph, we get a straight line (Linear Relationship) i.e 'output power = input power + Gain' - so if the gain of an amplifier is 10 dB, then a 1 dBm input signal will result in an output of 11 dBm and a 10 dBm input signal will result in a 21 dBm output signal. ...read more

What is Antenna Efficiency?

What is a Gain Equalizer?

Jan 3, 2018

Antenna Efficiency is the ratio of power radiated (Prad) by the antenna to the power supplied (Ps) to the antenna. The efficiency of an antenna is usually measured in an anechoic chamber where an antenna is fed with some power and the strength of the radiated electromagnetic field in the surrounding space is measured.An ideal antenna has 100% antenna efficiency i.e., it transmits all the power fed...read more

What is Antenna Directivity?

In general, RF amplifiers demonstrate a characteristic that their gain decreases with frequency as shown in Graph 1 below. Likewise, RF Cables and Passive components have a characteristic that involves insertion loss and frequency, but their insertion loss increases with frequency as shown in Graph 2 below. Those characteristics can pose significant risk when used without compensation in Satellite...read more

Aug 13, 2018

Directivity is the measure of the concentration of an antennas's radiation pattern in a particular direction. Directivity is expressed in dB. The higher the directivity, the more concentrated or focussed is the beam radiated by an antenna. A higher directivity also means that the beam will travel further.An antenna that radiated equally well in all directions would be omni-directional and have a d...read more

What is dBc?