If you have used cable and antenna testers before, you will understand that before each measurement is performed, Reopening the circuit – short circuit – load calibration is a very cumbersome and time consuming task. However, here you will be happy to see that in most cases you will use FieldFox's calibration ready (CalReady) And with the QuickCal feature, you no longer have to use the calibration kit. It saves a lot of time and is especially suitable for measurements in difficult environmental conditions. For example at the top of the mast. First, scan the X-band horn antenna with a shorter test cable. Just like we did the acceptance test at the factory before we went to the field. First I press the Mode button to make sure the meter is in CAT (cable and antenna test) mode. Then I press the Meas button and select the return loss test.
Set the start frequency to 5 GHz and the termination frequency to 14 GHz. At this point you can see the return loss of the instrument being scanned. Change the scale to 5 dB/div, This way we can see more clearly, we are measuring the return loss. The return loss is represented by the Y axis, and the frequency is represented by the X axis. But now I have not calibrated. If I press the Cal button, you will see many calibration options: Simple response calibration and fast calibration, the latter can make Our calibration eliminates the need for mechanical calibration parts. We can also perform a complete open-short-load calibration as needed. Each FieldFox meter is pre-calibrated at this reference point before leaving the Agilent facility. We are happy to be able to measure the response of the cable and antenna.
The cable is a very short, good quality low loss cable. Therefore, the return loss shown is from both the antenna and the cable. Then we no longer need to perform any calibration. This is before the field test A factory validation test that can be accepted. If you need to eliminate the effects of the test cable, Or if you have a longer cable, then we use a quick calibration method. First disconnect the cable attached to the antenna, press the Cal button and select Quick Calibration. The on-screen diagram shows the order and manner of connections. Start calibration, it will display "Keep port 1 open (no connection)". Then press the Measure button and it will proceed with the optional Step 2 step: Connect a 50 Ω load to the end of the cable. I will skip this step and press the Finish button. FieldFox has now been calibrated without any mechanical calibration kits. I will reconnect it to the antenna. Without considering the influence of the test cable, Now we measure the return loss of the antenna. As you would expect, Press the Marker button to open several cursor markers, I will open the cursor 1 marker.
Then open another cursor. And we can save the current result to the U disk Or SD card and save it as a test report. Let us consider another situation here, That is, we have to diagnose the problems that may occur in the antenna installation on site. In this case, we need to check the antenna, wiring and connectors. All aspects must work in an orderly manner to ensure that the antenna transmits and receives signals efficiently. Common mistakes include: damage to the antenna or cable, usually caused by lightning strikes, corrosion, Accidental damage during maintenance, or improperly installed connectors on the RF cable, Or water ingress due to inadequate waterproofing of the connector. In order for the antenna and wiring system to work properly, all parts of the system must Similar to a 50 Ω transmission line at the transmit and receive frequencies. Any deviation (deviation of 50 Ω) will cause damage on the cable Any deviation from 50 ohms will cause the signal to reflect along the cable, and these reflections will decrease.
The power to the antenna or receiver. Fault location function in FieldFox It is possible to verify these reflected signals. It will tell us how serious these mistakes are, And where these errors are transmitted along the cable. Under this setting, I will still use a shorter one. Test cable and the same X-band horn antenna, between the two, now I have a length At 10 meters or 20 meters, if we want to test the cable, And any components added to the entire loop, then we press the fault point positioning button. We use the Y-axis to represent the return loss (dB) and the X-axis to indicate the distance being measured. The starting distance is 0 meters. The calibration plane is at FieldFox port 1. Now I use the calibration ready feature again. The termination distance is 100 meters. The length of the cable is no more than 30 meters.
If I press the Freq/Dist button, the termination distance is 30 meters. Also need to change the scale to 5 dB/div. It’s now showing a distance of 0 to 30 meters, and we can clearly See the reflections at various points on the cable. To ensure distance measurement and The accuracy of the return loss measurement, we have to set it in FieldFox The type of cable used. Press the Meas Setup button, Select the DTF cable specification, edit it, save it and load it into the cable, and you will see that we loaded the pre-set cable. It is a RG8 or LMR or LDF standard cable loaded directly into the FieldFox memory. If the cable you are testing is not on this list, you can simply add it manually. Simply enter the speed factor and loss value. I have chosen the cable type LMR195. Now we press the downstream button and open the cursor 1.
If I set it to 0 meters, you will see a slight rise in the track line. It will return a return loss value of approximately 40 dB. This is the quality test cable and The junction of the FieldFox port 1 RF connector. If we move the cursor along the trajectory, we can see the second lift. The return loss at the point where the test cable is connected to the LMR195 is 40 dB. I can prove that when disconnected, you will see 100% reflection in a distance of 1 meter. I reconnected the cable, as we can find Other errors that may exist on the cable. Here, these small lifts are due to Caused by minor cable damage, the peak here is at the connector to Between the antenna fly leads. All are in compliance with the test index's 25 or 30 dB return loss value. Finally, very large, the rise at the end of the antenna is the response of the antenna itself.
So you can see that the antenna is 19.44 meters away from FieldFox. I am replacing this very good connector now, plugging in a cheaper adapter. You immediately observe that this response is significantly increased. If we use a cursor here to identify, you will see a return loss of 26.9 dB. This is acceptable in the real world. But this may indicate that the signal is attenuated. You may need to fix it during the next field test. There is an easier way to set the cursor at the peak instead of rotating the button. If I press the downstream button 2 and then press the Peak button, the cursor 1 will be immediately Reach the peak on the screen. We open the second cursor, Then move to the next right peak. Then open another cursor and continue to set to the right peak. I can press the downstream button and open the cursor list.
You will see the distance (meters) and return loss value of each cursor that has been opened in the list below the track. This is a great way to generate test reports. We can save the contents of the screen to U disk or SD card, and put it in the report or send it to the customer by email. You may notice that under the measurement button, In addition to the DTF that can be expressed in dB, the DTF can also be represented by the standing wave ratio. This is similar to the previous measurement of return loss, we can only measure the standing wave ratio of the antenna. We can also display return loss and fault point distance in the same display at the same time. If I press the More button, we can even perform a single port line loss test.
This is very useful. If the meter has a network Or tracking function, which will make it easy to measure the loss of two ports. But both ends of the cable must be connected to FieldFox. When the cable is placed at the antenna mast, you can only touch one end of the cable. Simply connect the FieldFox to one end of the cable to measure the line loss. This makes it very convenient to make measurements in the field. In short, we are able to measure the return loss of the antenna And standing wave ratio, can also measure the DTF, return loss and standing wave ratio of cable and antenna systems. In addition, we can measure the loss of the cable by simply connecting one end of the cable. We don't have to use a calibration kit at any time. However, you can still calibrate using traditional open circuit shorts and loads. But with FieldFox, you don't have to use them many times. For more information on the Agilent FieldFox Microwave Analyzer, Please contact your local sales representative or visit the website below.