Find The RF Filters For Wireless Communication

RF filter, or radio frequency filter, comprises inductors, capacitors, and resistors. These are an imperative component in the wireless technology landscape. The purpose of it is to filter the signal frequency in communication channels. It suppresses unwanted frequency signals and allows signals that meet a specific frequency to pass. 

RF filters for wireless communication are governed by frequency, amplitude, wavelength, and phase properties. In addition, the movement and behavior of RF signals are affected by reflection, diffraction, absorption, scattering, free space path loss, gain, and attenuation. These behaviors determine whether the user receives enough RF filters for wireless communication. 

There are four RF filters:

• Band stop filter
• Bandpass filter
• Lowpass filter
• High Pass filter

Functioning of Band Stop | Tunable RF Notch Filter

A band-rejection or band-stop filter passes most frequencies unchanged. However, it reduces or weakens those in a specific range. The purpose of  the Tunable RF filter is to remove a narrow band of frequencies or a single frequency. It is used in the audio system to remove interfering frequencies like powerline hum. In software-defined radio and radio receivers, it is used to remove a single interfering frequency. 

Depending on the design, a notch filter can be either active or passive. An active filter contains amplifying elements like an op-amp, and a passive filter is made of passive elements like capacitors, inductors, and resistors. 

A Tunable RF Filter is one whose band-reject frequency range can be tuned or controlled. A tunable RF notch filter or band-reject filter has the characteristic that the band’s center frequency can be set with different values, whether electronically or mechanically. 

Some of the tunable Rf notch filters are listed below:

Name	Application	Type	Bandwidth	Package Type
K&L Microwave – D5CTN – 4000/6000-100MHZ-O/O-MQI	Wireless Communications	Digitally Controlled	100 to 400 MHz	Module with Connectors
Ranatec – RI 268	WiFi, 5G NR, 4G	Digitally Controlled	5/160 MHz	Rackmount
Micro Lambda Wireless, Inc. – MLFR-0218	Electronic Warfare	YIG Filter	50 MHz	Module with Connectors
K&L Microwave – D5TNF-650/1000-3MHz-N/N-GRI	ATE Labs, Wireless Communications, Military	Digitally Controlled	15 MHz	Benchtop
K&L Microwave – 3TNF-30/76-N/N	ATE Labs, Wireless Communications, Surveillance	Mechanically Controlled	1 to 2.5 Hz	Benchtop
Teledyne Microwave Solutions – F3874	Electronic Warfare	YIG Filter	50 to 90 MHz	Module with Connectors
Micro Lambda Wireless, Inc. – MLFRD-0206	Electronic Warfare	YIG Filter	20 MHz	Module with Connectors
Ranatec – RI 266	Test & Measurement	Digitally Controlled	5 & 100 MHz	Rackmount
WainWright Instruments – WTRCT10-2400-2700-20-40-40M-1	LTE, TD-SCDMA, CDMA, DECT, Wifi, WLAN, WiMax, 5G N	Digitally Controlled	20 MHz	Module with Connectors
Micro Lambda Wireless, Inc. – MLFR – 0618	Electronic Warfare	YIG Filter	25 MHz	Module with Connectors

Difference between Lowpass filter and Band Pass Filters 

Band Pass filters have high-frequency and block unwanted signals in the wireless RF system. These filters have a bandwidth and center frequency and only allow the signals within a specified bandwidth to move through. The signals that are outside of the bandwidth are attenuated. They are widely used in wireless receivers and transmitters.

A lowpass filter (LPF) is a device that allows low-frequency signals to pass through and blocks signals that are above a specific frequency. The difference between a low pass filter and a high pass filter (HPF) is their function. A lowpass filter attenuates content or signals more than its cutoff frequency, and a high-frequency filter attenuates signals below the cutoff frequency. 

Industries That Are Primarily Dependent On RF Filters For Wireless Communication 

RF notch filters are essential as they control the signal so that the data moves with minimal interference. With the help of Rf filters, the external interference created by neighboring communication systems can be easily blocked. 

Additional Read: How Does RF Bandpass Filter Improves Signal Transmission?

RF filters allow global navigation satellite systems, Wi-Fi, public systems, and other bands to co-exist simultaneously. It is among the vital core technologies to address next-generation systems such as telemedicine, intelligent facilities, autonomous vehicles, and other highly connected applications. 

Prominent sectors like below listed are largely dependent on RF filters for wireless communication:

• Aerospace
• Drone systems
• Military
• Automatic vehicles
• Satellite

Things You Should Know About RF Filters For Wireless Communication

Electronic components called RF Filters for Wireless Communication are used to reduce noise or allow or block specific signals or frequencies for the passage of unwanted signals. Lowpass, highpass, and bandpass filters are examples of common types.

Microwave radio frequency filters are the main electronic component of microwave communication systems, including radars, test and measurement systems, Duplexers & Diplexers etc. With proper design and configuration, the filter is a passive circuit that can produce microwave radio frequency filtering.

RF front-end modules are becoming an important component of mobile devices as they become more powerful and support a wider range of network frequency band combiners. 

For example, recent mobile phones must support at least 3G, 4G, 5G, and WiFi, as well as other network standards such as GPS, each standard requiring a specific RF front-end module. Band Combiners play a vital role here. 

Why is an RF filter necessary?

As wireless communication applications develop, people’s demand for data transmission speeds increases. In the 2G era, only a few people will use their mobile phones to access the WAP version of the web and the Internet, and the data speed required is around 1 KB/s. 

Network traffic has increased dramatically in the 3G era due to the widespread use of smartphones, the use of carrier networks to send and receive emails, and the use of multiple applications. The required data rate is approximately 50 kb/s. Increased use of spectral resources and complex communication methods correlates with higher data rates. 

These two problems go hand in hand: due to the scarcity of spectrum resources, spectrum must be used to its full potential to meet consumer demand for data rates. To enable the use of a variety of devices in crowded environments, mobile phones must be able to cover a wide range of frequencies. 

Sufficient spectral bandwidth can then be allocated. Since 4G, carrier aggregation technology has been used to allow devices to simultaneously transmit data on different carrier frequency spectra to meet data rate requirements. Band Combiners can be very useful for this. 

Quality factor Q and insertion loss are, respectively, the two most important signals of an RF filter. Current communication protocols require very excellent selectivity to pass signals within the passband and block signals outside the passband because the frequency difference between different frequency bands becomes smaller and smaller. 

The RF Filters for Wireless Communication passband can be reduced, and its Q increased, thus improving selectivity. Insertion loss is an important parameter in addition to quality factor Q. Insertion loss, or signal power loss, describes how the filter reduces the bandwidth signal.

SAW and BAW are today’s two most widely used RF filter implementation techniques. Surface Acoustic Wave (SAW) is a piezoelectric RF filter. 

When a voltage is applied, the crystal mechanically deforms, converting electrical energy into mechanical energy. The mechanical energy used to crush or disperse this crystal is converted into electrical energy. 

Charges are created on both sides of the crystal structure to create a voltage across the terminals and/or allow current to flow through the terminals. 

Alternating mechanical deformations in solids have the potential to produce sound waves that travel between 3,000 and 12,000 meters per second. The acoustic wave propagates on the surface and forms a standing wave in the surface acoustic wave filter, the quality factor of which can be hundreds.

Basic types of filters: 

The filter is a device used to filter waveforms. It is a circuit that only allows signals of a specific frequency band to flow, interrupting transmissions outside the band. 

Lowpass, highpass, and bandpass filters are the three basic types of filters, and they can be passive or active depending on how the circuit is designed to operate.

• Lowpass filter

Inductance permits low-frequency signals to flow while blocking high-frequency ones, whereas capacitors have reverse properties. A lowpass filter is a filter whose signal can pass through an inductor or a filter connected to the ground by a capacitor, which attenuates low-frequency signals less than high-frequency signals.

• High pass filter

A first-order linear differential equation can typically be used to describe the properties of a highpass filter. It shares the same left side as a first-order lowpass filter. Instead of the excitation source itself, just the right side is the derivative of the excitation source.

• Bandpass filter

A bandpass filter is a circuit that effectively mutes signals at other frequencies while only allowing certain frequencies to pass. 

Band-pass is frequently used in electronic design due to its selectivity to signals. You can trust Duplexers & Diplexers for this. 

Conclusion

RF Filters for Wireless Communication are essential and can help you a lot in making your work easy. If you want any help regarding Duplexers & Diplexers then Anatech Electronics can help you.

Read More – What Are Standard RF Filters And Their Benefits?