John Hambleton No Comments

TYPES OF RADIO ANTENNAS

Radiall designs and manufactures radio antennas for military and defense applications, from soldier radios to military vehicles. We specialize in handheld radio antennas, manpack radio antennas, vehicular antennas and LMR/PMR antennas. Keep reading to learn about each one.

Handheld Radio Antennas

This range includes all types of antennas integrated on soldier radios. The antennas cover VHF, UHF, L and S bands from 30 MHz to 3 GHz and can be offered as multiband. Radiall’s handheld radio antennas are available in overmolded whip or blade form factors. It is possible to attach a gooseneck to the antenna or a sealing foot at the base of the antenna.

Manpack Radio Antennas

Soldiers use manpack radios to communicate during tactical operations. Radiall offers a wide range of tactical communications antennas (VHF/ UHF/L/S Band) dedicated to manpack radios. Several form factors are available including whip, blade and plastic overmolded. These antennas are available as mono-band or multi-band and can withstand harsh environmental conditions (IP67/68, salt, fog, vibrations) per MIL-STD-810G.

Vehicular Antennas

Vehicular antennas are radio communication antennas that can be integrated on any kind of military vehicle. They cover frequency bands from 225 MHz to 2.4 GHz, including the UHF band. We offer vehicular antennas in a robust tubular form factor that can be mounted on a standard NATO base. Multiband versions are also available. Our vehicular antennas have been tested per MIL-STD-810G.

LMR and PMR Antennas

LMR and PMR antennas are used by policemen, fireman, security guards and others for private mobile radio communication. These robust solutions utilize an overmolded form factor. They cover frequency bands from 380 to 490 MHz (TETRA band) and can be offered as multiband, with the option to include GPS. We offer quarter wave antennas with a monopole design.

Discover Radiall’s comprehensive range of antenna solutions.

Mark Hoffman No Comments

WHAT ARE MICROWAVE PHASE SHIFTERS?

Microwave phase shifters are devices that alter the phase of the electromagnetic oscillations at the output of a microwave transmission line, with respect to the phase of the oscillations at the input of the line. The phase of a transmission line can be shifted by increasing the length/time of the transmission line or by altering the wavelength.

In microwave solutions, phase shifters are passive microwave devices that change the phase angle of an RF signal. RF waves can combine to strengthen or weaken a signal, depending on if the waves are identical or different. Identical frequencies will strengthen a signal, whereas opposing ones will weaken it. Phase shifters change the angle of an RF signal so that it doesn’t interfere with the wrong signals. This technology maintains strong performance by providing low insertion loss.

We can understand this concept better by considering noise-cancelling headphones, which use some phase shifting principles. In an audio application, instead of adjusting RF and microwave energy, the shift involves the phase of an audio wave in relationship to another wave. Noise-canceling headphones reduce noise by inserting a sound wave that is 180 degrees out of phase with the surrounding noise. The new sound wave has been shifted to cancel out the first wave, thus reducing the noise you hear.

This noise-cancelling example illustrates an extreme result that we do not typically see in microwave applications. Generally, microwave phase shifters only need to change minor increments of a wavelength to achieve the desired performance results.

Phase shifters are used in a variety of applications, including phase modulators, frequency up-converters, testing instruments and phased array antennas. Radiall designs and manufactures analog phase shifters for microwave components and coaxial phase shifters for space qualified components.

Altum RF is a ACETEC.com principal. Visit Altum RF to find out more about their capabilities.

Mark Hoffman No Comments

Design of a mmWave MIMO Radar

This article written by Tero Kiuru and Henrik Forstén, VTT Technical Research Centre of Finland Ltd., Espoo, Finland. Full article is here: Design of a mmWave MIMO Radar | 2021-01-10 | Microwave Journal

Radar uses reflected radio waves to determine the range, angle or velocity of objects. These detection systems, which were once the exclusive domain of the aerospace and defense industry, are now gaining popularity in the consumer industry, most notably for automotive radar applications used in adaptive cruise control and autonomous driving assistance systems.

The complete article in the January, 2021 issue of Microwave Journal

Mark Hoffman No Comments

Akoustis Technology Optimized for 5G & WiFi 6E

Next generation connectivity architectures are demanding solutions that support high-frequency, ultra-wideband, and high-power coexistence RF filter. Years of R&D have uniquely positioned us to handle the industry’s challenges and push the boundaries of what’s possible bringing you the highest quality filter solutions in the market.

All the latest news from Akoustis

Mark Hoffman No Comments

The Study of Pulse Recovery Times in GaN LNAs: Part I

The Gallium Nitride (GaN) high electron mobility transistor (HEMT) is well known for its use in microwave and millimeter wave power amplifiers due to its high breakdown voltage and ability to handle high RF power. Recently, GaN technology has also been used to create low noise amplifiers (LNAs) in the microwave region, as the noise properties of GaN are similar to other semiconductor materials, most notably Gallium Arsenide (GaAs). In many microwave systems, LNAs are subject to unwanted high input power levels such as jamming signals. One of the features of LNAs made from GaN is the ability to withstand these input power levels without the need for a limiter, due to the inherent robustness of the device. Indeed, this is one reason GaN LNAs are supplanting their GaAs counterparts, since GaAs LNAs typically require a front-end limiter, which adds to the cost and degrades the performance of the LNA.

Despite the ability to operate without a limiter, GaN LNAs, however, are not completely immune to the effects of high input power. The problem occurs when both a high power jamming signal and the desired signal are input to the GaN LNA, and then the jamming signal is suddenly turned off. Under this scenario, the GaN amplifier does not recover immediately, as there is some residual distortion of the desired signal before normal operation returns. This phenomenon is known as pulse recovery time and is fast becoming an important parameter with regards to LNAs in general. Past researchers have studied pulse recovery times in GaN LNAs, although this work has been limited in scope. One study presented recovery times of less than 30 ns in some amplifiers, but these measurements only utilized a coherent jammer, and the overall number of measurements was limited. A second investigation of pulse recovery time was performed on a GaAs LNA with a limiter. The limiter not only effected the small signal performance, but it also increased the recovery time when high power was applied. Further research has been performed on the degradation of GaN HEMT noise performance after exhibiting DC and RF stress, which can cause forward gate current and damage the gate device. However, this work did not explicitly address pulse recovery times in LNAs. Other papers have similarly analyzed the survivability of GaN amplifiers to high input power overdrive, but again this work offers little understanding of pulse recovery times.

MEASUREMENT TEST SETUP

A setup designed by Custom MMIC uses two signal generators, where the first provides the out-of-band interfering signal at 8.5 GHz, and the second provides the desired continuous wave (CW) in-band signal at 7.5 GHz. The interfering RF signal from #1 is pulsed using a single pole single throw (SPST) switch controlled by a square wave with a low duty cycle. We chose to pulse the signal path, as opposed to the bias circuitry of the interferer amplifier, due to the fast rise/fall time of the SPST, which is on the order of 1.8 ns. Additionally, pulsing the power supply caused high levels of ringing to appear at the output. The interfering signal was amplified by an external power amplifier (PA) and then added to the desired signal with a passive power combiner. We utilized a circulator, terminated in a 20 dB pad and a high power 50 Ohm load, between the combiner and the device under test (DUT) in order to prevent any high power mismatch signal from reflecting back into the PA. The output of the DUT was then attenuated with an additional 20 dB pad, sent through a band pass filter with a pass band of 7.25 to 7.75 GHz, and then input into a digitizing oscilloscope. The filter attenuates the interfering signal to allow for an accurate measurement of the pulse recovery time. Finally, we utilized two different oscilloscopes for the measurement. A Tektronix digital serial analyzer oscilloscope was used to measure the recovery time for the shorter pulse widths, while a Hewlett Packard Digitizing Oscilloscope was used to measure the recovery time when longer pulses were used.

The test procedure consisted of varying the pulse width and the input power of the interfering signal, while keeping the power of the desired signal constant at -10 dBm. A summary of the test conditions including pulse widths, repetition rates, and power levels of the interfering signal are presented in our tech brief . Notably, the input power of the interfering signal was varied between 15 and 27 dBm, with the total energy delivered to the DUT being the important parameter of concern. All measurements with short pulses were performed on the Tektronix oscilloscope, whereas the long pulse measurements were performed on the Hewlett-Packard oscilloscope.

Blog by Custom MMic

Learn more about the study of pulse recovery times in GaN LNA’s.