An overview of L-Band Directional Coupler

In the radio frequency field, equipment like “directional couplers” play a major, albeit silent and low-key role. The device is described as “passive devices that are used to couple a specific proportion of the power travelling in one transmission line out through another connection or port”. Directional couplers are used in the different radio frequency bands for a wide array of applications, from RF amplifiers to transmitters and receivers, test and measurement tools and more.

Technically, an L-Band directional coupler refers to directional coupler that has an operating frequency band covering the range of frequencies from 1-2 GHz. However, an L-Band directional coupler typically has a wider bandwidth than this. One of the our L-band directional coupler has an operating frequency from 700MHz to 2.7 GHz.

Refer to this page to see the full range of directional coupler products that we have. AWG Tech also provides customized RF directional coupler. Contact us if you need a directional coupler that is built to your specific requirements.

The Technical Specifications Of L-Band Directional Couplers

Let’s take a brief yet interesting look at directional couplers for the L-band.

Directional Couples Are Constructed In Various Ways

There are a lot of ways for constructing directional couplers, as couplers come in different variants, like L-band directional couplers (and are constructed using stripline, coaxial, lumped element and others). These devices are also packaged differently, from using solder pins to substrate carriers and more.

Directional couplers are basically 4-port devices, and the 4 identified ports are named: Input (Port 1), Transmitted Output (Port 2), Coupled (Port 3) and Isolated (Port 4). The terms in the brackets refer to the port’s alternative names.

Electronics experts point out that the main line would be the one between port 1 and 2, which is generally suited to carry high power levels, and it may be equipped with bigger RF connectors too, as long as it’s a unit that’s equipped with RF connectors.

And despite the different construction methods used, what these devices have in common is that they have the ability to tap a sample of the input power, without considerably affecting the original signal.

What Exactly Is The L-band?

The L-band is actually a remnant of the Cold War, literally, because it was extensively used by the NATO, or North Atlantic Treaty Organization. The L-band was designated to the radio frequencies from 1 to 2 GHz ( or equivalent to the wavelengths between 30 and 15 cm).

The allotted frequency assignments were in line with NATO’s Joint Civil/Military Frequency Agreement. And while they’re regarded as obsolete, they’re still widely utilized to identify military radio spectrum requirements for crisis management planning, training, electronic warfare, as well as in direct military operations.

What Are The Major Directional Coupler Specifications?

Like any other electrical or electronic component or system, there are major specifications associated with directional couplers (especially those used for the I-band). These include Coupling Loss, Main Line Loss, Directivity and Isolation.

Coupling Loss refers to the amount of power lost to the coupled port (port 3) and to the isolated port (port 4). Main Line Loss refers to the “resistive” loss due to heating. Directivity refers to the power level difference between port 3 and 4, and this is a measure of just how independent the couple and isolated ports are. Isolation refers to the power level difference between ports 1 and 4.

An L-band directional coupler separates or segregates signals based on the direction of signal propagation. These are also utilized to unequally split the signal flowing in the mainline, as well as to fully pass the signal flowing in the opposite direction. Thus, they work in as much as the same way as electronic filters, although they greatly vary in their technical specifications and direct tasks.