Radio frequency/microwave filters (RF/microwave filters) accept or reject signals according to the signal's frequency. The way the signal passes through a filter varies according to the filter design.

There are several performance specifications for RF/microwave filters. These include voltage standing wave ratio, bandwidth, specified frequency insertion loss and ripple. When looking at RF/microwave filters, consider the various types.

1. Bandpass filters are RF electronic filters, such as in surface acoustic wave (SAW) filters and cavity filters, with active or passive circuits that turn away signals from out-of-band frequencies.

2. Band reject filters, also called bandstop filters or notch filters, are RF and microwave filters with tuned circuits preventing signals within a specified band of frequencies from passing through when they shouldn’t.

3. Low pass filters made by microwave filter designers let low frequencies pass and reject high frequencies. High pass filters do the opposite.

Action Steps
The best contacts and resources to help you get it done

Consider RF filter manufacturers who offer a variety in product

Look for a RF filter manufacturer carrying numerous filter designs to find the components that best suits your purposes. Specifically look for companies constantly expanding inventory, and ask what new products are available in the near future.

I recommend: Trilithic offers a wide and varied inventory of filters for commercial and military use. It offers limited quantities of new designs within a two-week period in most cases. If you are looking for filters that can handle a wide range of frequencies, consider MTK Electronics. It has designed over 3,000 different filters according to customer specifications.

Purchase from RF filter suppliers who are knowledgeable in your field

Purchasing microwave electronic filters from a supplier who knows the ins and outs of the business is a smart move. Suppliers frequently know changes in the industry as well as what might be coming down the pipe in regards to equipment that will make your job easier.

I recommend: Masline Electronics deliberately incorporates customers' needs into its stock system. If you want information on complex RF/microwave components, consider Dexter Magnetic Technologies. It maintains an ISO 9001:2000 certification, and it is a manufacturer and supplier of RF/magnetic filters that offers a high level of support to clients.

Order a custom microwave filter to fulfill your product needs

While most manufacturers carry a product in stock that you can use, you may find that a microwave filter design fits your needs better. Manufacturers work with businesses that have unique specifications, and many consult with customers to meet unique criteria.

I recommend: Known for its custom designs in RF filters, Airsan provides solutions for industrial and HVAC use. Another custom provider of RF/microwave filter solutions is Photo Sciences. This ISO9001:2000 certified company uses advanced technologies to create products that meet a client's criteria.

Tips & Tactics

Helpful advice for making the most of this Guide

• •  Consider renting or purchasing refurbished microwave filters to save on cost.