The resonant frequency or frequencies of a cavity depend on several factors, including the dimensions of the cavity, the materials that form the cavity, and how energy is launched and/or extracted from the cavity. A resonant cavity is sometimes referred to as a form of in-circuit waveguide, short-circuited at both ends of the waveguide structure so that EM energy builds within the cavity at a designed frequency or band of frequencies. The size of a cavity resonator, for example, is a function of the desired resonant frequency and the characteristics of the PCB materials used for the resonator. PCB materials with higher dielectric constants will support smaller cavity resonators for a given frequency than circuit substrate materials with lower dielectric constants.

A patch antenna, which is also known as a microstrip antenna, can be fabricated with standard printed-circuit-board (PCB) processes using high-frequency laminate materials. An antenna can be as simple as a rectangular patch above a ground plane or as elegant as a complex array of patches, customized for a specific radiation pattern. As with other printed circuits, the choice of circuit material can greatly impact the performance possible from the final antenna design. That choice should be guided by a clear understanding of how a circuit material’s electrical and mechanical properties relate to the performance of a patch antenna.

Conductor surfaces on a printed-circuit board (PCB) can vary widely, from a “smooth-as-glass” finish to a more typically rough profile. As detailed in an earlier ROG Blog, a conductor surface profile can impact the performance of a sufficiently high frequency circuit, increasing insertion loss and dispersion and even causing propagation delays and changes in the effective dielectric constant of the circuit. But are all RF/microwave transmission-line technologies affected by conductor surface profiles in the same way? What about designs based on coplanar-waveguide (CPW) transmission lines, or stripline? Do they require circuit materials with low-profile conductors, or are they less affected than microstrip by conductor surface roughness?

The ROG Award Contest kicked off in November 2011. We invited customers to enter the contest by telling us about their applications using Rogers?materials. For the next several months, customers shared stories about their Best Digital Application, Most Challenging Board Build, Most Unique and Creative Use of Material, Most Innovative Design, Longest Product Life, and Most Extreme Conditions, all accomplished together with Rogers?materials. One winning application was chosen for each category.

Multilayer microwave PCBs can pack much circuitry into a small volume. But creating a multilayer microwave circuit is more than just stacking layers. It takes planning and knowledge of the multilayer fabrication process. In particular, an understanding of how prepreg materials are used in multilayer circuits can be helpful.

Radiation loss can be a concern in microstrip circuits at higher microwave frequencies. Fortunately, its effect can be minimized by reducing the number of discontinuities in a circuit design, and by carefully weighing the choice of circuit substrate material in terms of thickness and dielectric constant, where thinner materials and higher dielectric constants can both contribute to lower radiation losses.

Evolution of the electronic systems in automobiles and other vehicles is exciting to watch, and many technologies once associated with the military, such as radar systems, are becoming available to average drivers. As highlighted in the previous ROG blog, 24-GHz short-range-radar (SRR) systems are being offered more and more in car models around the world. But vehicle designers and manufacturers are also looking ahead to the greater resolution possible with 77- and 79-GHz automotive radar systems. And for that evolution in automotive electronic systems to truly take place, printed-circuit-board (PCB) materials are important building blocks that will enable the potentially much safer automobiles of the future.

Automotive electronic circuits were once as simple as switches for headlights and windshield wipers. But modern automobiles take advantage of electronic circuit technology more than ever, often working with high-frequency signals at RF, microwave, and even millimeter-wave frequencies. For consumers, these advanced systems promise greater safety and an enhanced driving experience. For the manufacturers of these systems, these automotive applications offer the potential of bringing high-frequency technologies to millions of users. And to suppliers of printed-circuit-board (PCB) materials, such as Rogers Corporation, these emerging applications pose challenges of providing high-performance reliable circuit materials at acceptable prices that help fuel mass-market applications.

As strange as it may sound, the use of circuit defects is a growing trend in high-frequency circuit design, especially for passive circuits such as filters. More precisely, the trend is in the increased use of defected ground structures (DGSs) and defected microstrip structures (DMSs) to alter the responses of microstrip circuit designs. Just what are these DGS and DMS forms, and does incorporating them into a high-frequency circuit change the way the PCB material should be specified?