RF & Microwave Community

ANDREI MULLER - 3D Smith Chart Tools S.R.L.

May 23, 2017

Theoretical answer:On a 2D Smith chart one is bounded by the unit circle, all the circles which never get together on a 2D Smith chart "long" to meet again but never do since the points are thrown at infinity in all directions. The circuits which are mapped out of the unit circle Smith chart represent circuits with negative resistance which occur in active circuits design( amplifiers, transistors,...read more

What is the difference between a Diplexer and Duplexer?

Filters

Raghav Kapur - everything RF

Nov 28, 2016

A Diplexer is a 3-port passive device that allows two different devices to share a common communication channel. It consists of two filters (Low Pass, High Pass or Band Pass) at different frequencies connected to a single antenna. In the figure below, Signal A at Frequency A enters the Diplexer and passes through Filter A to the antenna. Singal B at frequency B, passes through Filter B to the same...read more

What is a Virtual Antenna?

Antennas

Carles Puente i Baliarda - Fractus Antennas

Mar 21, 2017

Virtual Antenna is the commercial name for the "Antenna-less" technology based on a new generation of tiny components named antenna boosters. Antenna boosters are miniature, surface-mount (SMT), off-the-shelf, components that replace conventional customized PIFA/Printed antennas for mobile/wireless connectivity applications. Being much smaller than the operating wavelength (typically below 1/30 or...read more

What is an Isotropic Antenna?

Raghav Kapur - everything RF

Jan 5, 2017

An isotropic antenna is a theoretical antenna that radiates equally in all directions - horizontally and vertically with the same intensity. The antenna has a gain of 1 dB in the spherical space all around it and has an efficiency of 100%. The concept of an isotropic antenna is often used as a reference antenna for the antenna gain.Antenna Pattern of an Isotropic Antenna in the Vertical & Hori...read more

What is a Dual Directional Coupler?

Couplers

Raghav Kapur - everything RF

Feb 20, 2017

A regular directional coupler is a 4 port network, similar to what is seen in the diagram below. Port 1 is the input port, port 2 is the output port, port 3 is the coupled port and port 4 is the isolated/terminated port. The power passes from the input port (port 1) to the output port (port 2) in transmission line 1. A portion of the power is coupled with transmission line 2, the amount of power c...read more

Seeing Through the Noise

Test & Measurement

Dr. Jon Bradley

CRFS

Following 20 years in electro-optics and the telecoms industry, I’ve recently shuffled along the electromagnetic spectrum and joined the RF community in earnest. I’m busy preparing a range of educational seminars which we will be announcing soon and thought it might be a great way to introduce those by sharing a few of my own thoughts and experiences in the RF domain.First, what a culture shock!We...read more

What is a RF Limiter?

Active Components Limiters

Raghav Kapur - everything RF

Nov 4, 2016

RF Limiters are used in Transmit/Receive modules to prevent damage to the low noise amplifier due to excessive power at the input of the system. LNA's and other components in the receive chain of a wireless systems are very sensitive, as they are usually designed to accept small signal levels which are then amplified.In ideal situation where the input power to a system is within the limits of the ...read more

Creating an Airport Runway Foreign Object Debris Detection System Based on Millimeter-Wave Radar

Radars

Shunichi Futatsumori

National Instruments

The Challenge:Analyzing and displaying the GB/s class radar data from high-resolution 96 GHz millimeter-wave radar front ends to detect small debris on airport runways.The Solution:Using the NI PXI platform and FlexRIO to achieve the real-time radar signal processing based on the FPGA hardware clock with a high-data throughput rate, and using LabVIEW code for the radar signal processing to reduce ...read more

What is a Bias Tee?

Bias Tees

Raghav Kapur - everything RF

Mar 20, 2017

Bias tees are the components, that are used to supply DC currents or voltages to bias RF circuits. A Bias tee is a three-port device. The structure of the device can be seen below in Figure 1. A signal that consists of RF + DC is incident at port 1 of the Bias Tee. The capacitor blocks all DC signals from getting through to port 2 and only allows the AC/RF Signals to pass through.Whereas, the indu...read more

V-Band vs E-Band for Backhaul Applications

Backhaul Millimeter Waves

Raghav Kapur - everything RF

Nov 28, 2016

With an increase in the deployment of small cells for LTE and 5G, we are seeing more wireless backhaul solutions being used to provide base station connectivity. Most backhaul solutions today operate at Millimeter wave frequencies. However, there is a lot of debate as to which mm-Wave frequency band is the right frequency band for these applications. The two most popular bands being used for small...read more

What is the difference between dBi and dBd?

Antennas RF Basics

Raghav Kapur - everything RF

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

What is the difference between a monopole and dipole antenna?

Antennas RF Basics

Glenn Robb - Antenna Test Lab Co

Jun 21, 2017

All antennas require two terminals, just as a circuit element such as resistor requires two terminals for current flow. It is easy to see that a resistor can have AC (RF) current applied to its two terminals, and dissipate energy.With a dipole, the two terminals are intuitive as well. Each “arm” of the classic dipole is ¼ of a wavelength long, symmetrical, and each is connected to a terminal. Howe...read more

What is Foreign Object Detection?

Wireless Charging

Raghav Kapur - everything RF

Dec 14, 2016

In wireless charging, metal objects that get close to a wireless power transfer system may couple a portion of an electromagnetic field and heat up. The detection of foreign objects around the system (metallic or magnetic objects) is of key importance due to their ability to absorb energy from the wireless power supply field in the form of heat (parasitic heating) and possibly become a hazard.Simu...read more

BeiDou Frequency Bands

GNSS

Raghav Kapur - everything RF

Mar 27, 2017

The BeiDou Navigation Satellite System or BeiDou-2 was formerly known as COMPASS. This system will consist of 35 satellites, which include 5 geostationary orbit satellites for backward compatibility with BeiDou-1, and 30 non-geostationary satellites (27 in medium Earth orbit and 3 in inclined geosynchronous orbit), that will offer complete coverage of the globe. The BeiDou GNSS solution operates i...read more

GLONASS Frequency Bands

GNSS

Raghav Kapur - everything RF

Mar 27, 2017

GLONASS (Globalnaya Navigatsionnaya Sputnikovaya Sistema) is a Russian Aerospace Defense Force-operated satellite-based navigation system.The GLONASS GNSS solution operates in the following frequency bands:L1 Band: 1589.0625 MHz to 1605.375 MHzL2 Band: 1242.9375 MHz to 1248.625 MHzL3 Band: 1201 MHz

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