BUMPS (Bike Up the Mountain Points Series) is a cycling series for riders who love the challenge of one good climb after another…for a total of 10 climbs! Each year, BUMPS introduces 10 races on nine mountains in the Northeast. The courses feature varying lengths and pitches. Riders accumulate points from up to five races.
Held on June 27th, The Okemo Bike Climb starts in Jackson Gore, VT and winds it way up 5.8 miles to the top of Okemo Mountain. At 2,200 feet (670m), Okemo boasts the largest vertical drop in southern Vermont. Basically the first two miles offer a brief warm-up, then riders are faced with an aggressive 11% grade to the summit.
We want to share a huge congratulations to Marc for participating in the Okemo Bike Climb, and for finishing 3rd in his class! Thank you for sharing your photos and bringing your XRD jersey along for the ride.
Now you can download the microwave PCB Microapps presentations given by John Coonrod, Market Development Manger, at the International Microwave Symposium, IMS/MTT 2015:
High-frequency circuit designers must often consider the performance limits, physical dimensions, and even the power levels of a particular design when deciding upon an optimum printed-circuit-board (PCB) material for that design. But the choice of transmission-line technology, such as microstrip or grounded coplanar waveguide (GCPW) circuitry, can also influence the final performance expected from a design. Many designers may be familiar with the stark differences between high-frequency microstrip and stripline circuitry. But GCPW circuitry, while also having its differences from traditional microstrip, also offers many benefits for high-frequency circuit designers to consider. In making the choice, it can help to understand just what different types of PCB material can have on the microstrip and GCPW circuits. The differences between the two structures can be seen in the illustration below.
As a quick comparison, microstrip circuitry features a signal conductor fabricated on top of a dielectric layer, with a conductive metal ground plane on the bottom of the dielectric material. GCPW achieves an extra level of grounding and isolation by fabricating a signal conductor in between two ground conductors, all on the top of a dielectric layer, with an additional ground plane on the bottom of the dielectric layer. Conductive-metal-filled viaholes connect the top-layer and bottom-layer ground planes for consistent ground performance. In addition, many GCPW circuits employ ground straps to provide electrical connections for the two top-layer ground conductors for consistency around circuit discontinuities, such as junctions.
As different as the two circuit approaches may appear, the tight spacing of the top-layer grounds and signal conductor for the GCPW approach enables it to achieve low impedances and to tune the impedance by adjusting the spacing between the grounds and the signal line. The impedance increases as the spacing between the top-level ground conductors and the signal conductor increases. In fact, as the spacing of a GCPW circuit’s top-layer grounds from the signal conductor increase, those grounds have less effect on the circuit and a GCPW circuit with enough spacing between the top-layer grounds and the signal conductor electrical resembles a microstrip circuit.
Why use one transmission-line approach over the other? Obviously, microstrip has an “elegant simplicity” to it, which makes it easier to fabricate and even easier to model via computer than GCPW circuits. With their strong ground structure, GCPW circuits are capable of lower-loss performance at much higher frequencies than microstrip circuits, and offer great potential for designs working well into the millimeter-wave frequency range, even to frequencies of 100 GHz and beyond. Microstrip which, with stripline, is one of the most popular transmission-line formats at microwave frequencies, suffers increased circuit losses into the millimeter-wave frequency range, making the circuit technology less efficient for use at frequencies of 30 GHz and beyond.
What roles do PCB materials play in the choice of using microstrip or GCPW transmission-line approaches? Such material parameters as dielectric constant (Dk) and consistency of Dk through the material will impact the electrical performance of either transmission-line approach. The manner in which the electromagnetic (EM) fields travel through each circuit structure will have a great deal to do with the effective Dk that is exhibited for a particular circuit material, since those EM fields can flow within the dielectric material and outside of the dielectric material. In microstrip circuits, for example, with their top-side transmission lines and bottom-side ground planes, the EM fields are contained mainly within the dielectric material between the two metal planes, with a high field concentration at the edges of the signal conductor. For microstrip circuits, the effective dielectric constant is closely related to the specified Dk of the PCB material, such as Rogers’ RO4350B™ PCB material, which has a process specification of 3.48 in the z direction (thickness) at 10 GHz. The material’s Dk is held to impressive ±0.05 tolerance across the material.
The effective Dk of a PCB material will essentially determine the size of circuit structures required to achieve a specific characteristic impedance, such as 50 ohms. So, for microstrip transmission lines on, for example, RO4350B circuit material, circuit width for 50 ohms will be based on a Dk of 3.48. But for GCPW using the same material, because the circuit’s effective Dk is reduced because more of the EM field is in the air above the circuit rather than in the PCB dielectric material, the effective Dk is lower when compared to microstrip. The difference in effective Dk for GCPW and microstrip depends on the thickness of the substrate used by the GCPW circuitry and the spacing between the ground-signal-ground conductors on the top layer.
PCB fabrication issues have less impact on microstrip circuits than GCPW circuits. For example, PCB copper plating thickness variations have little effect on the performance of microstrip circuits but they can impact the performance of GCPW circuits. Thicker copper plating on PCBs for microstrip circuits can slightly reduce the insertion loss and lower the effective Dk of the circuit. For GCPW circuits, PCBs with thicker copper plating lead to an increase in the EM fields between the top-layer ground, signal, and ground field paths, with more of the EM fields in the air above the GCPW circuit. With more of the fields in the air above the circuit, signal losses decrease and the effective Dk of the PCB decreases for a GCPW circuit, all because of thicker PCB copper plating thickness.
As a quick comparison, microstrip supports moderate-bandwidth circuits through microwave frequencies, although with high radiation loss at higher, millimeter-wave frequencies and difficulty at achieving mode suppression at millimeter-wave frequencies. Microstrip circuits suffer minimal sensitivity to PCB fabrication techniques and material characteristics, such as copper plating thickness and copper thickness variations. In contrast, GPCW suffer only moderate radiation loss at millimeter-wave frequencies, and are capable of moderate or better mode suppression at millimeter-wave frequencies, making this circuit technology a strong candidate for designs at 30 GHz and higher. In addition, GCPW circuits are only moderately sensitive to PCB fabricate techniques and variations, making them well suited for production-volume applications at higher frequencies.
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Technology and Invention is a series by Rogers Corporation about the innovation, pioneering spirit, and transformative technologies that are creating a cleaner, safer, more connected world. Part 1: Historical Milestones.
Part 2: The Promise of Plastic
“Have you ever seen a polypropylene molecule?” a plastics enthusiast once asked me. “It’s one of the most beautiful things you’ve ever seen. It’s like looking at a cathedral that goes on and on for miles.” – Susan Frienkel in Scientific American
The word “plastic” comes from the Greek verb plassein, which means “to mold or shape.” The term was first recorded in the early 1900s, about 100 years after the early chemists starting working with natural rubber.
Plastics can be shaped because of their long, flexing chains bonded in a repeating pattern into one gigantic molecule. This structure promised a glorious revolution.
The plastics revolution of the late 19th and early 20th centuries held out the promise of a new material, even cultural democracy. “[Plastics] freed us from the confines of the natural world, from the material constraints and limited supplies that had long bounded human activity,” said Susan Frienkel in “A Brief History of Plastic’s Conquest of the World.” She continued, “That new elasticity unfixed social boundaries as well. The arrival of these malleable and versatile materials gave producers the ability to create a treasure trove of new products while expanding opportunities for people of modest means to become consumers.”
Parkesine is considered the first man-made plastic, patented by Alexander Parkes, Birmingham, UK in 1856. Made from cellulose treated with nitric acid as a solvent, it won a bronze medal at the 1862 World’s Fair in London.
Modern plastics development took a big turn in the 1860’s when a young printer, John Wesley Hyatt, used cellulose nitrate (celluloid) as a way to produce billiard balls from materials other than the rapidly diminishing supply of ivory.
In 1899, Arthur Smith patented phenol-formaldehyde resins for use in electrical insulation. Shortly thereafter, cellulose acetate, a thermoplastic, was developed; similar in structure to cellulose nitrate, it was found to be safer to process and use.
The commercial development of today’s major thermoplastics began in the 1930-1940’s. The advent of World War II brought plastics — polyvinyl chloride, low density polyethylene, polystyrene, and polymethyl methacrylate. — into demand, largely as substitutes for materials in short supply, such as natural rubber.
During this era, the major thrust of research at Rogers Corp. was centered in the new field of polymeric materials. In 1932, Rogers began a long-term association with Dr. Leo Baekeland, a Belgium-born, American chemist who invented Bakelite in 1907. Bakelite was an inexpensive, nonflammable, versatile plastic that marked the beginning of the modern plastics industry. A popular product, Bakelite was the first plastic to hold its shape after being heated – also known as a thermoset plastic. Rogers’ association with Dr. Baekeland would lead to a family of phenolic resin plastics, Fiberloy, for insulation in early electric motors.
By the end of World War II, Rogers Paper Manufacturing Company was renamed Rogers Corporation, reflecting the broad diversity of products, services, and markets.
The Modern World of Plastics
The first decade after World War II saw the development of polypropylene and high density polyethylene and the growth of the new plastics in many applications. “In product after product, market after market, plastics challenged traditional materials and won, taking the place of steel in cars, paper and glass in packaging, and wood in furniture,” said Frienkel.
In 1949, Rogers introduced fiber-reinforced polymer materials – named Duroid® – for gaskets and electrical insulation. In 1953, RT/duroid® glass microfiber and ceramic fiber-reinforced PTFE materials were developed, initially as chemical resistant gasket materials. Rogers entered the Space Age when Duroid® 5600 was incorporated in the Jupiter space vehicle as the electronic window material.
In the mid 1950s, Rogers acquired a small elastomer fabrication company in Connecticut, which developed Mektron® molded circuits for use in mechanical switches and timers in appliances, automobiles, and other industrial applications. This was the beginning of an extended period of sustained growth for Rogers Corp., for polymers, and for the new world of electronics.
Next: The Age of Electronics
Rogers Corporation provides innovative solutions for power electronics, advanced foams for cushioning and protective sealing, and high-frequency printed circuit materials. For over 180 years, we have empowered breakthroughs in reliability, efficiency, and performance, to help our customers build a cleaner, safer, and more connected world.
A plethora of standards have been developed or are in the works for connected car / intelligent transport system (ITS) technologies. Implementation is now largely in the hands of automotive manufacturers.
In 2015, more than 20% of vehicles sold worldwide will include embedded connectivity and more than half will be connected by embedded, tethered, or smartphone integration. By 2025, every new car will be connected in multiple ways.
A variety of development projects are in the works related to in-car, car-to-driver, and car-to-x connectivity. In a recent survey of 250 CxOs in European automotive companies, challenges remain in software development, security, and testing (Figure 1).
Jaguar, for instance, has added a new pothole warning system to the Land Rover. Using data from the road-sensing magnetic shocks, “the system records the magnitude of road impacts, tags their location, and uploads them to a cloud server where other drivers would be warned of a potential pothole, sunken manhole cover, or deep storm drain. When combined with a stereo camera – two optical cameras positioned close together for judging depth – the car could precisely locate that hole in the road, snap a pic, and report it to the local public-works authority. The Range Rover’s shocks would also prepare for impact if the driver doesn’t heed the warning, tensing and slackening accordingly.”
The next stage of the project at Jaguar Land Rover’s Advanced Research Centre in the UK is to install new road surface sensing technology in the vehicle, including an advanced forward-facing stereo digital camera.
When it comes to infotainment and smartphone integration, several competing vendor-initiated connectivity systems are in play.
Google Android Auto leverages the strength of Google Maps, and also supports messaging, music, weather, and other smartphone apps. Following closely on Google’s heels, Apple’s CarPlay integrates iPhone apps with a car’s digital systems. It works with Siri voice control and the car’s control knobs, buttons, or touchscreens. Functions include maps, phone, messaging, music, news, audiobooks, and more.
But Toyota hasn’t jumped on board either yet. Their engineers are studying whether to adopt SmartDeviceLink (SDL) technology, an open source version of Ford AppLink. AppLink gives drivers command and control of smartphone apps through dashboard buttons, display screens and voice recognition technology.
The Hyundai Sonata is the first car to integrate Google Android Auto. Chevy will offer both Android Auto and Apple CarPlay in 14 models that will debut this year. But Ford’s SDL technology is already in more than 5 million Ford vehicles globally, giving it a big head start.
The automotive radar market is evolving into a mix of frequencies – 24 GHz, 77 GHz, and 79 GHz – as technology allows and economics permit, said John Coonrod, Market Development Manager at Rogers’ Advanced Connectivity Solutions. For circuit designers and component specifiers, the rules change at these higher millimeter-wave frequencies.
The RO4000 Series High Frequency Circuit Laminates are an excellent choice for cost/performance for 24GHz radar applications. The RO4835has been developed for extreme stability, even when exposed to the harsh environments of automotive applications. For high moisture environments, the RT/duroid® 5870 and 5880 high frequency laminates have a very low dielectric constant and extremely low water absorption characteristics. For 77GHz automotive radar applications, the RO3003 laminate is the preferred choice due to high material uniformity.