Premium band reject filter: Filtronetics, Inc designs & manufactures frequency control products including high, low, band pass, notch, reject, electronic filters, TCXO, VCXO, and related oscillators and quartz crystals in um-1 and SMD packages in the KHz, MHz and GHz range.

FILTRONETICS, Inc. offers a  variety of Quartz Crystals. We have both Surface Mount and Thru Hole parts.

Filtronetics Inc manufactures a wide array of filters, crystals, oscillators, coils, and ceramics.

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designs and manufactures a complete array of filters, oscillators and crystals. 

Band Reject Filter

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An ideal band reject filter completely attenuates frequencies above its lower cut-off frequency and below its upper cut-off frequency. Conversely, for frequencies greater than the upper cut-off and frequencies less than the lower cut-off the signal is allowed to pass. This region is referred to as the passband. In practice, one finds that the attenuation has a finite slope. Thus, either a shape factor or stopband width must be specified. In addition, due to spurious modes both the high side and low side of the passband will eventually degenerate. This necessitates the inclusion of an outer pass bandwidth. Other names for a band reject filter are band elimination filter, band reject filter, band suppression filter, and band reject filter.

Filtronetics, Inc. supplies band reject filters that utilize a wide array of technologies. The most common is LC band reject filter, or lumped element, which is comprised of inductors and capacitors. We also offer crystal band reject filters. For higher frequency applications, microwave band reject filter structures are utilized. Both LC and crystal band reject filters can be made with elliptic or monotonic designs.

The center frequency and stop bandwidth determines the type of technology employed in constructing a band reject filter. A quartz crystal band reject filter is used when a narrow band filter is required. This is due to the crystal’s high, unloaded Q-factor, which is in the range of 10,000 to 100,000. Crystal filters with low insertion loss in the passband are achievable for stopband widths from 0.005% to 0.1% of the center frequency. Moreover, center frequencies are available from 5 KHz to 600 MHz. Passbands are restricted to no more than 25% of the center frequency for wideband crystal band reject filter designs. LC passbands can be much wider.

Microwave band reject filters can be designed as low as 50 MHZ. Conversely; LC band reject structures start at DC and end at 1 GHz. The stopband width is mathematically limited to twice the center frequency. At this upper bandwidth, it becomes a highpass filter. The lower limit is determined by insertion loss limitations and stability. In extreme cases, filters can be as narrow as 0.5% of the center frequency. Filtronetics, Inc. offers custom band reject filters from DC to over 2 GHz.

Our band reject filters have been utilized in systems that are in space, military, undersea, airborne, testing, and commercial applications. We can produce from one to over a million band reject filters for your application. Band reject filters are available in Surface mount (SMD), Through-hole, and connectorized (BNC, TNC, SMA, or N filter) packages.


FILTRONETICS, Inc. located in Kansas City, Missouri was established in 1970. Over the past 35 years, Filtronetics, Inc. has developed a broad line of frequency products for diverse applications ranging from communications to instrumentation for commercial, industrial and military applications. Filtronetics, Inc. is known for the ability to consistently provide the highest quality custom LC, Microwave, Ceramic, SAW and Crystal filters available. Filter types include bandpass, low pass, high pass, notch diplexer and dual band. The company’s mission is to become a valued supplier for all customers, which range from University researchers to Fortune 500 Companies. In addition to custom filters, a broad line of crystals, monolithic filters and oscillators are offered. Filtronetics, Inc. works with our customers to guide them through the development process with technical support for critical filter and oscillator applications such as PCS, GSM, E-GSM, WLL, B-WLL, LMR, ISM 915, ITM 2000, GPS, TRS, LMR, CT-2,E-TACS, SAT COM ATM, SONET, LAN, data processing and high reliability applications. Filtronetics, Inc. offers various alternatives and related pros and cons to optimize the cost benefit rational. Filtronetics, Inc. continually updates its Kansas City facility and equipment with the latest technology.

Quality Team:
Quality is the foundation of Filtronetics, Inc. success. The Quality Control department combines more than 35 years of experience. Current quality standards are based on and registered to ISO-9000. Customer or project specific requirements are also available, as well as conformance to IPC-610, MIL-STD-202, MIL-STD-883 and many other standards.

Filtronetics, Inc. is responsible for the design and production of numerous high reliability filters used by the United States government and government related programs. 

Filtronetics, Inc. has participated by providing electronic components and electrical engineering expertise in many leading government sponsored electrical component testing programs.

Filtronetics Inc • 6010 Parretta Drive • Kansas City, Missouri MO (USA) 64120 • Tel: 816-231-7375 Fax: 816-241-0368 Email:

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