SW2012N                                                 Amtronix Instruments, Inc.
  0.5 - 1500 MHz  Return Loss Bridge    
Amtronix Instruments, Inc. 
Ph 716-763-9104
Amtronix Instruments, Inc. has discontinued the SW2012N Return Loss Bridge, however,  Masters Communications  is now making them. We have worked with Masters Communications and can report that all specifications including accuracy, directivity and overall quality of their RLB1500 is the same as our SW2012N. The Masters Communications RLB1500 is a direct replacement for the Amtronix SW2012N.

SW2012N Return Loss Bridge
    Turn your service monitor or signal generator / signal receiver into an accurate antenna analyzer. This will provide the same accuracy as antenna analyzers costing thousands more. The SW2012N is a commercial duty 0.5 - 1500 MHz return loss bridge (RLB) for your antenna/feed line testing. Bridges are individually tested and include a performance graph. This unit has a 0.5 - 1500 MHz range and minimum 35 db directivity (40 dB typical).  The unit has high quality type N connectors for all ports and a new configuration with the input and output ports conveniently on one side. The new design will withstand 4 watts of accidental power input to the DUT port. Use your existing rf generator and receiver/power meter/spectrum analyzer to make accurate measurements.
    Please note: This product is being discontinued. We have just a few units left in stock. The SW2012N continues to be an excellent working rugged and dependable product. We originally manufactured this bridge to provide a lower cost alternative that had compairable or superior performance to more expensive units. The profit margin has been slim and for that reason, this product will soon be discontinued. We will continue support should it be necessary. Another company will soon continue the manufacturing of this bridge with some design changes. Their contact information will be posted here as soon as they have the product to sell.
The Basics of a Return Loss Bridge
      In simple terms, the return loss bridge is a device used to measure RF power reflected from a load or device under test (DUT) when power is sourced to the device through the RLB. The return loss bridge has 3 ports. An RF signal generator is applied to the input port. The output port provides an RF signal to go to a measuring device such as a spectrum analyzer, power meter or other device used to measure this signal. The DUT port connects to the device that you are testing (antenna, coax, etc.). A signal is generated into the input port. The RLB applies this signal to the DUT.  The DUT will reflect a portion of the signal that it receives (due to impedance mismatch).  This RF signal appears at the output port. The closer your DUT impedance is to 50 ohms, the lesser the signal will be at the output port. A perfect 50-Ohm DUT will have no reflected power so a perfect RLB will have no output signal at its output port (infinite return loss). If a non-50-Ohm load is at the DUT port, there will be an RF signal at the output port. The extreme cases are for the DUT to be a short or an open connection. This will cause maximum reflected power and, therefore, maximum signal at the RLB output port. Return loss is measured from the worse case (short or open) with 100% power reflected. It's the difference amount in dB of the reflected signal of your DUT compared to the worst case reflected signal. The further you go from "worse case" the better. The higher the return loss number, the closer the DUT is to 50 ohms. This is somewhat the opposite when compared to SWR ( high SWR means high reflected power or poor match) For example: with an open or short connected to the DUT port and an RF signal source generating into the RLB input port, let's say we measure the RF power at the RLB output port to be -22 dBm. If the open or short were replaced with your load at the DUT port, the amount of power at the RLB's output port would then change. If the output signal is now measured to be -42 dBm, this would be a return loss of 20 dB. The amount of reflected power is 20 dB less than the worst case. This is equal to an SWR of 1.22:1. If this were an antenna, it would be considered an excellent match with about 1% of the power to the antenna reflected. A return loss of 10 dB would correspond to an SWR of 1.91:1 with 10% of your power reflected. This is generally considered a poor match. Most commercial systems want to see a return loss of 18 dB or better.

Directivity
    Directivity is the measure of how well the RLB isolates 2 opposite traveling (foreward and reflected) signals. As the reflected signal becomes smaller and approaches the specified value of the RLB directivity, the measurement uncertainty becomes larger. To get accurate return loss (SWR) measurements, it's important to have a bridge with directivity of 10 to 20 dB higher than what you want to measure. The higher the directivity, the greater the accuracy the RLB can measure small signal levels of reflected power. A perfect 50-Ohm load should have infinite return loss, which translates to no output signal from an RLB. If we could build a perfect RLB, the output port would show no signal with a perfect 50-Ohm load. In the real world, the highest quality RLB would show a return loss of up to 50 dB.  50 dB would be pushing the physical limits because the N connector itself has a tiny amount of return loss. This is great, but most techs really don't care about directivity above 20 dB. A higher quality bridge will have higher directivity than needed to provide better accuracy at all levels. The SW2012N has guaranteed directivity of 35 dB with typical directivity being  40 dB or better over the 0.4 - 1500 MHz range. A 20 dB directivity means that you'll see as little as 1% of reflected power. A directivity of 30 dB is 0.1% and 40 dB is 0.01% ( 1/10000 of worse case reflected power level). The SW2012N Return Loss Bridges are individually tested and include a performance evaluation graph.


SW2012N Return Loss Bridge



SW2012N Return Loss Bridge

Using your RLB