In the News

Death Grip Revisited

As every RF and microwave engineer well knows, connecting two separate antennas will ruin the performance or each one. The fact that this elementary point seemed to be lost on Apple's engineering team when developing the iPhone 4 seems to indicate that RF technology remains a "black art," even at Apple Computer. The company's response to angry customers when they connected the two elements by innocuously placing a finger on the "The Hole" on the lower left side of the phone and dropped call after call was disappointing. 

First it was blamed on an overoptimistic determination of signal strength by the phone's firmware, which showed "more bars" than it should have for a given signal strength. Of course, this was irrelevant. The second was not to "hold it like this" (the "death grip"), as demonstrated in person by Steve Jobs. The third was to complain that the signal strength of all phones with internal antennas is reduced when held in certain ways, which is true but also irrelevant, since that was not the problem with the iPhone 4. Fourth was to offer owners free rubber bumpers or cases, thus verifying that the problem was indeed "The Hole".

The point here is not (wholly) to disparage Apple for its BP-like treatment of the problem, but to point out that even at Apple, which arguably has some of the world's finest minds, the problem was still missed. Thus providing that there will always been jobs for RF engineers.

GaN Moves In On GaAs

Is the reign of GaAs as the King of Microwave Compound Semiconductor Materials in jeopardy? Some people say that gallium nitride (GaN) may do to GaAs what GaAs did to silicon since the 1980s. That is, take a massive slice of its market share. GaN has appealing performance characteristics, such as 10 times the power density of GaAs, high efficiency, high operating voltage (higher power well into the millimeter-wave range), and others. It is the current fair-haired boy of RF power technologies in the defense labs, and has been deployed in electronic warfare systems. GaN is now moving in on GaAs and silicon in the commercial arena, particularly for cellular infrastructure and cable hybrid amplifiers, its exceptionally high power density means fewer devices are required to generate a specific power level, which mitigates their higher cost, or so their champions say.

However, GaN devices cost far more than GaAs and silicon LDMOS RF power transistors, their reliability has not been documented over hundreds of millions of parts as have those of the competition, and there are massive portfolios of GaAs devices available from many vendors throughout the world.

One thing is certain, the coming years will be very interesting as GaAs and GaN duke it out in the defense and commercial sectors.

 Trivia Questions 

Greetings {FIRST_NAME},

A Message from Sam Benzacar

   

Get to Know Ceramic Filters

Ceramic filters are less expensive to produce than either LC or cavity type filters and are smaller than all but Surface Acoustic Wave (SAW) or Bulk Acoustic Wave (BAW) filters. They can be realized in bandpass and bandstop configurations as well as duplexers and diplexers, although not broadband lowpass or highpass filters. Their maximum input power is about 5 W and useful frequency range is 400 MHz to 6 GHz.

Ceramic filters are made from ceramic resonators one quarter wavelength of the filter's center frequency, as well as a capacitive coupling network. Ceramics used in ceramic filters have dielectric constants of 30 to 90. The higher its dielectric constant, the more sensitive to temperature the resonator will be. Ceramics with very-high dielectric constants result in filters that are very small but with lower Q and higher sensitivity to temperature variations and extremes. Ceramics with lower dielectric constants produce filters with higher Q but larger size and much less susceptibility to temperature variations.

Ceramic filters are surface-mountable and most have Chebyshev responses. Bandwidths of 20% or more are achievable with stopband attenuation limited to about 40 dB. Ceramic filters are made in two ways discrete resonator and monoblock. Discrete-resonator filters consist of a series of quarter-wave ceramic resonators with capacitors forming a coupling network and the coupling value of the capacitor depends on the desired bandwidth of the filter. The final performance characteristics of the filter are obtained by tuning. The filter's components are soldered onto a printed circuit board and the assembled filter is then soldered onto the host circuit board.

A monoblock ceramic filter is formed from a single block of ceramic material. The shape resulting from the fabrication process has the desired resonance and coupling factor, and tuning ability is limited but rarely required. These filters do not require a printed circuit board to secure their elements together as they are integrated in the molded monoblock structure. The entire block, representing the finished filter, is mounted directly onto the host circuit board.

There is much more to learn about ceramic filters and we would be happy to answer any questions you have. Please contact me at (973) 772-4242 or by e-mail at technical@anatechelectronics.com. You can 

 

What's News at Anatech Electronics

Two New Manufacturers Representatives

We're happy to announce the appointment of new manufacturer's representatives responsible for sales of the company's products in different areas of the U.S.

- Martonix will represent Anatech Electronics in Southern California and Southern Nevada. The has company has been representing high-tech companies for more than 20 years and can be reached at (805) 499-6385.

- Electronic Instrument Associates will represent Anatech Electronics in Illinois, Wisconsin, Iowa, Minnesota, North Dakota, South Dakota, Indiana, and Michigan. Electronic Instrument Associates was founded in 1971 and covers the Midwest via offices in Chicago, Minneapolis, and Indianapolis. The company can be reached at 630-924-1600.

 

 

 

  If you have any questions regarding our products, or comments on our newsletter, please email us at: filters@anatechelectronics.com

Featured Products

30-dB Dual-Directional Coupler

The AM1515DC870 is a 30-dB dual-directional coupler that operates from 30 to 3000 MHz with insertion loss of less than 0.2 dB, coupling flatness of 1 dB, directivity of at least 25 dB, and VSWR of 1.151. The coupler handles 50 W average and 3 kW peak power, measures 6.25 x 1 in. square, and uses Type-N female and SMA female connectors.

This product is available on our webstore AMCrf.com

770 MHz Cavity Bandpass Filter

The AB770B844 cavity bandpass filter has a center frequency of 770 MHz, making it well suited for applications within the new wireless bands soon to be occupied by high-speed wireless data services. It is accompanied by other models in the 700 MHz band as well as custom models available from Anatech Electronics. The AB770B844 has a bandwidth of 13.2 MHz, passband of 763.4 to 776.6 MHz, and insertion loss at 770 MHz of less than 2 dB. Rejection is 50 dBc at 766 and 785 MHz and power handling ability is 20 W. The unit measures 4.7 x 2.3 x 2 in. and employs SMA female connectors.

 This product is available on our webstore AMCrf.com

WiFi Weatherized Cavity Bandpass Filter

The Wifi2412-1O is a cavity bandpass filter with a center frequency of 2412 MHz and is designed for use in WiFi hotspots located outdoors where they are exposed to hostile environmental conditions. The filter has a 22 MHz passband (2401 to 2423 MHz), passband ripple of 1.2 dB, insertion loss at 2412 MHz of less than 3 dB, rejection of more than 60 dBc at +/- 25 MHz of the center frequency and more than 90 dB at twice the center frequency. It handles 50 W, uses Type-N female connectors, and has an operating temperature range of 0 to C.

 This product is available on our webstore AMCrf.com

400 to 500 MHz Circulator

The AM400-500CIR133 circulator covers 500 to 500 MHz handles 100 W average and 500 W peak RF power, and has isolation of 18 dB. Insertion loss is 0.5 dB, isolation is 18 dBm and maximum VSWR is 1.5:1. Operating temperature range is 0 to C.

 This product is available on our webstore AMCrf.com

Answers to last month's Trivia Questions 

1. How much time-- in months-- does the average American motorist spend during his lifetime waiting for the red lights to turn green? Six Months

2. What great thinker proved a lunar eclipse is the circular shadow of the Earth on the moon? Aristotle

3. What essential piece of office equipment did Johnann Vaaler invent in 1900? The paper clip