Asked 3 years, 7 months ago. Active 3 years, 7 months ago. Viewed 3k times. Coplanar transmission line mutual coupling ratios and impedances? A math version? Did you want to include hybrid splitters which are also directional couplers?
Just keep in mind that its not a good idea to understand RF stuff intuitively. I would say ''its not a good idea to only understand RF stuff intuitively''. However, the intuition is a different beast as that from basic circuit analysis, and really requires thinking in terms of waves and interplay of E, H, and I. Show 5 more comments. Active Oldest Votes. The Photon The Photon k 3 3 gold badges silver badges bronze badges.
If I'm wrong, someone else can answer based on a different understanding and OP can give their answer the check mark. Add a comment. Henry Crun Henry Crun 4, 8 8 silver badges 12 12 bronze badges. Sign up or log in Sign up using Google. Sign up using Facebook. Complete coupler catalogs from over manufacturers have been listed in this cateogry.
Use the parametric search tools to narrow down on products based on your requirement. Download datasheets, compare products, request quotations and get pricing. Any queries made via everything RF are directed to the company and relevant distributors who get back to you directly. Key Specifications: Types of RF Couplers: - Directional Coupler: This is a four port device — with an input and output port, a port for the coupled signal and a port that is terminated internally.
Featured Suppliers. More Calculators. What is a Notch Filter? What is the difference between a monopole and dipole antenna? Once you understand the basics, you can invent your own version of a coupler because all it requires is for you to select some transmission line structures not necessarily the same as each other and arrange them in such a way that some portions of the two structures are not isolated from each other and that, over some distance along the lines, the fields and waves of one line interact with the fields and waves of the other line.
The devil is in the details and you are free to manipulate these details until the structure performs as you wish within the confines of your imagination and the difficulty of building it.
For this purpose we will use the nomenclature of the schematic symbol for a coupler, assuming a backward-wave coupler. Let's first look at some definitions using S-parameters. Let port 1 be the input port, port 2 be the "through" port, port 3 the coupled port and port 4 the isolated port. Ideally, power into port 1 will only appear at ports 2 and 3, with no power at port 4, but in real couplers some power leaks to port 4.
For an incident signal at port 1 of power P1 and output powers P2, P3 and P4 at ports 2, 3 and 4 , then:.
Two additional characteristics used to define coupler performance are phase unbalance and amplitude imbalance between the coupled port and the through port over the operating frequency band. Both characteristics are used to define the bandwidth of the coupler.
Note that these numbers are supposed to be positive in dB. Quite often, microwave engineers present these quantities as negative numbers, it is not a great faux pas. Note that directivity requires two, two-port S-parameter measurements, the other quantities require only one. Directivity is the ratio of isolation to coupling factor. In decibels, isolation is equal to coupling factor plus directivity. The earliest directional coupler is generally credited to H. Affel of ATT whose U.
Patent was filed in and granted in The illustration from the patent is shown below and appears to be a two wire transmission line coupled to another two wire transmission line. Shown next to it, doing pretty much the same thing, is a pair coaxial lines joined together with a portion of their outer shields removed to allow for coupling. In the s at the MIT Radiation Laboratory, a wide variety of waveguide couplers were invented and characterized, including the Bethe hole coupler, multihole couplers, and the Schwinger coupler.
In the s coupled TEM line directional couplers were designed by a group at the Stanford Research Institute primarily using stripline transmission line structures. Next came microstrip couplers which were planar and open-sided which made it convenient to mount semiconductor and other devices.
The popularity of these designs was hastened by their low manufacturing costs compared to waveguide couplers. Currently, great strides in new microwave materials and fabrication techniques as well as new computer-aided-design tools for layout and circuit simulation including 2D and 3D EM analysis programs are giving you the opportunity to revise and improve on existing coupler designs as well as to create entirely new families of designs. Flexible substrates, low-loss substrates, multilayer substrates with vias, semiconductor substrates, substrates with thermal expansion rates matched to semiconductor devices, micro-machined substrates, and metamaterials provide additional options for innovative designs.
While specific ports are given labels on a device, this is normally more of a physical constraint as some ports will be manufactured to carry higher powers than others.
In fact any port can be the input, and this will result in the directly connected port being the transmitted port, the adjacent port being the coupled port, and the diagonal port being the isolated port. As with any component or system, there are several specifications associated with RF directional couplers.
The major RF directional coupler specifications are summarised in the table below. Couplers are not as widely used as some RF components like attenuators, mixers and the like, but in areas closer to the antenna where power may need to be sampled, they are widely used.
For example a directional coupler may be used within a meter detecting the standing wave ratio, but they also have many other applications. RF directional coupler basics An RF directional coupler has four ports and these are normally defined as in the list below: Input Port 1, Incident Transmitted Port 2, Output Coupled Port 3, Forward coupled port Isolated Port 4, Reverse coupled port Terms in brackets refer to alternative names for the ports that may be seen on occasions- they give a little more explanation of the function of the coupler port than just the name.
Four port directional coupler symbol While specific ports are given labels on a device, this is normally more of a physical constraint as some ports will be manufactured to carry higher powers than others.
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