Testing Antenna Systems with Tower Mounted Amplifier
Contents
1. Figure 3 illustrates the RF signal path of a dual duplex TMA with bypass circuitry and its interaction with the YBA250 when testing an antenna system On the Rx side the RF signal path between the YBA250 and the antenna depends on the condition of the bypass circuitry When the bypass relay is closed the LNA is bypassed and the YBA250 sees the antenna through the filter and the bypass connection When the bypass relay is open the YBA250 does not see the antenna but the output of the LNA Under this condition the uplink Rx side of the antenna cannot be tested Typically the DC voltage applied through the center conductor of the feed line is used to control the bypass circuitry How Filters and Amplifiers Affect the Measurement In order to demonstrate the effect of filters and amplifiers on the return loss we are going to measure areal antenna system Figure 4a shows a return loss measurement screen of an antenna system that includes a 42 foot feed line a jumper cable and a Yagi antenna 824 MHz 896 MHz It has a reasonable return loss with values greater than 18 dB 4 www tektronix com wireless AMPS EIA 553 x 15 15 85 Chan 820 00 44 to 900 00 344 M2 Measurement Method ae Calibration Return Loss Fast User aaah Trace 1 Normal l d Y Auto Scale 6 00 7 6 00 l 12 00 PRIA 18 00 Seen ae seed 3 3 VA D 24 00 LSAT 30 00 nn 422. 00 48 00 Stop MHz fo00 00 f 54 00 k 820 00 4 560 00 MHz 900 00 4 834800 0 848 800 Ovo 14 000 A 862 000 Y 820 000 MHz Ml 25 792 M2 24 058 M1 M2 1 735 Max gt 54 Min 16 728 dB gt Figure 4a No TMA AMPS EIA 553 iege e Chan 820 00 744 to 900 00 433 MHz Measurement Method i User Calibration Fast S g Return Loss x uto Scale Trace 1 Normal a do Y 6 007 gt i 0 00 Des A 12 00 f 18 00 VA gt 24 00 30 00 Stop MHz 36 00 42 00 l 200 00 7 48 00 N a 54 00 4 A S S 820 00 amp 960 00 MHz 900 00 4 834 800 0 865 600 9 0 1 29 680 M2 5 144 M1 M2 gt Figure 4b Blue LNA bypassed Yellow No TMA 30 800 A 840 000 Y 820 000 MHz 24 536 Max 43 147 Min 3 759 dB You then connect a TMA DD between the feed line and the Yagi antenna The Rx and Tx frequency bands for this TMA are 835 0 849 0 MHz and 880 0 896 0 respectively It also includes a bypass circuitry If you now measure again with no DC power applied to the TMA so that the bypass relay is closed you will find a result similar to the one shown in Figure 4b It shows both traces together and inside the Rx and Ix frequency bands you can see that the return loss is still greater than 18 dB The performance inside the Rx and Tx bands was not affected Outside these bands the return loss is much lower It is caused by th
3. 54 00 a a a a a ks20 00 4 960 00 MHz 900 00 4 834 800 0 848 800 O40 14 000 A 842 000 VY 820 000 MHz Mi 27 970 M2 21 888 M1 M2 6 082 Max 38 977 Min 3 759 dB gt Figure 4e LNA ON Blue failure Yellow antenna Procedure to Sweep Antennas with TMA Using the YBA250 When making return loss VSWR sweep measure ments the key is to bypass the LNA so that the test equipment can see the antenna on the Rx band The general procedure on the YBA250 is as follows gt Select Return Loss measurement gt f greater accuracy is desired perform a one port User Calibration at the end of the precision test jumper gt Connect precision test jumper to the RF port of the bias tee blue test point in Figure 1 gt Make sure the amplifier is bypassed If a bypass circuitry is not available in your TMA only the Tx band of the antenna will be swept www tektronix com wireless 5 Testing Antenna Systems with Tower Mounted Amplifier gt Application Note gt Select frequency parameters to cover Rx and Tx frequency bands gt Perform measurement Press Auto Scale you might obtained similar results to the blue trace in Figure 4b When the Return Loss VSWR in frequency mode shows a problem with the system a Distance To Fault DTF measurement is performed to find where the fault might be To improve distance resolution DIF requires sweeping with a wide frequency range The wider the frequency rang
4. Gain Normal Auto Scale EH to 10 00 EH MHz User Normalization 3 f Trace 1 Normal da Y F ooo 30 00 gt T 3 cit ae a T a a GRRRRREEEET SERRREEEEEEE SEREEREEEEE eeaREaEED seeneooeioaE meee 3 00 eN 14 00 F 25 00 4 ff Vt 36 00 47 00 58 00 M2 69 00 i So ppe 4880 000 k 820 00 865 00 MHz 910 00 Avg Insertion Gain 934 800 ovo I1 13 257 M2 0 150 M1 M2 gt Figure 5c nsertion Gain for a TMA DD Output Power Level 8 60 dB 20 dBm 855 600 MHz 2 6 13 494 Min 67 986 dB 45 200 Vs 842 400 A 13 107 Max Figure 5c shows the insertion gain of a TMA DD for both the Rx and Tx frequency bands 835 0 849 0 MHz and 880 0 896 0 respectively It has a 13 dB gain over the Rx band which complies with the manufacturer s specification For all TMA configurations single single duplex and dual duplex the measurement setup is the same connect the BTS port of the TMA to the bias tee YBT250 side and the ANT port of the TMA to the attenuator at TEST PORT YBA250 side This test setup might be difficult to realize when the TMA is already mounted on the tower www tektronix com wireless 7 Testing Antenna Systems with Tower Mounted Amplifier gt Application Note Testing Tower Mounted Amplifier after Installation Caution Please check your country s laws regarding transmitt
5. Kong 852 2585 6688 India 91 80 22275577 Italy 39 02 25086 1 Japan 81 3 6714 3010 Luxembourg 44 0 1344 392400 Mexico Central America amp Caribbean 52 55 56666 333 Middle East Asia and North Africa 41 52 675 3777 The Netherlands 090 02 021797 Norway 800 16098 People s Republic of China 86 10 6235 1230 Poland 41 52 675 3777 Portugal 80 08 12370 Republic of Korea 82 2 528 5299 Russia CIS amp The Baltics 7 095 775 1064 South Africa 27 11 254 8360 Spain 34 901 988 054 Sweden 020 08 80371 Switzerland 41 52 675 3777 Taiwan 886 2 2722 9622 United Kingdom amp Eire 44 0 1344 392400 USA 1 800 426 2200 USA Export Sales 1 503 627 1916 For other areas contact Tektronix Inc at 1 503 627 7111 Updated November 3 2004 For Further Information Tektronix maintains a comprehensive constantly expanding collection of application notes technical briefs and other resources to help engineers working on the cutting edge of technology Please visit www tektronix com E Copyright 2005 Tektronix Inc All rights reserved Tektronix products are covered by U S and foreign patents issued and pending Information in this publication supersedes that in all previously published material Specification and price change privileges reserved TEKTRONIX and TEK are registered trademarks of Tektronix Inc All other trade names referenced are the service marks trademarks or registered trademarks o
6. about typical TMA HMA configurations and their effects on reflection measurements A special focus will be set on the Insertion Gain and Insertion Loss while performing gain measurements of tower mounted amplifier and antenna isolation measurements Tektronix Enabling Innovation Testing Antenna Systems with Tower Mounted Amplifier gt Application Note Introduction Antenna systems are commonly tested from the ground level of base transceiver stations BTS by using an antenna sweeper such as the YBA250 With the growing demand for higher data rate applications there is a critical need to improve the uplink Rx sensitivity of new networks Tower mounted amplifiers TMA or masthead amplifiers MHA are installed near the receiver antenna at the top of the cell tower in order to increase the uplink sensitivity and improve the reception of weak signals Other benefits are the extension of coverage area the reduction of dropped calls and an increment of handset battery life The relative easy installation of the TMA makes it even suitable for upgrading existing base transceiver stations BTS Figure 1 shows an example of an antenna system with TMA In an antenna system without TMA a return loss or VSWR sweep indicates how well the antenna transmits power by measuring the power that it reflects compared to the power that it receives With the insertion of a TMA the reflected power might not come from the antenna itself b
7. gt Application Note Testing Antenna Systems with Tower Mounted Amplifier CDMA US Cellular Measurement Method Insertion sain Normal Auta Scale 30 00 7 19 00 4 00 3 00 14 00 25 00 36 00 47 00 4 56 00 69 00 50 00 k 520 00 Avg Insertion Gain 6 60 dB 45 200 WY 13 107 Max So 834 800 ooo O 580 000 M1 1s 25 M2 0 1501 M1 M2 chan 820 00 m Trace 1 Nor mal ER s 565 00 MHz J a 7 Le be be Lek L be be to 910 00 cee ser Nor malizaton 380 O00 O10 on i EEE EEE L Le Le Output Power Level 20 dBm 842 400 A 13 494 Min 655 600 pHs 67 986 dB In today s competitive environment it is very easy for mobile subscribers to change their provider This makes customer satisfaction very important for every network operator Network stability needs to be high and dropped calls need to be minimized On the other hand to reduce investment it is important to use a large cell size where possible and still have good coverage Tower Mounted Amplifiers TMAs or receiver preamplifiers or Mast Head Amplifiers MHAs allow the best sensitivity when larger cells and weak handset signals are prevalent To be most beneficial TMAs or MHAs need to be mounted as close to the receive antenna as possible This application note describes how to test Antenna systems with tower mounted amplifiers You will learn
8. cts of filters and amplifiers on your measurement as well as the procedures to sweep antennas with TMA This section now will move away from the Antenna system and uniquely focus on testing the TMA itself The YBA250 is capable of performing two port meas urements Insertion Gain and Loss when used in conjunction with the NetTek YBT250 A normalization kit such as the YBAC2 or equivalent is required to make more accurate insertion measurements Other accessories used for these tests are DC power supply Tektronix Part Number 119 7017 00 or equivalent Testing Antenna rile View Setup Tools LA EDIT o gt 12 6 2004 12 47 20 PM CDMA US Celular e LH 1 25 chan 220 00 galto 1000 p10 00 MHz Measurement Method User Normalization aY Insertion Gain Normal Trace 1 uia amp Fal z E 900 f E a a a es ee oa 6 00 3 7 5 00 4 f y Wa 3 00 4 7 2 00 1 00 Stop MHz a NONE PPD a Ce Se Se OR 1 00 4 mE 910 00 910 00 ogd Output Power Level COOC PET om 23 800 VY 866 000 A 920 400 MHz 0 003 Max 0 003 Min 0 020 dB IiE vea250 SxS Cm 12 47PM P gt Figure 5a G measurement after User Normalization k 820 00 4 965 00 MHz Avg Insertion Gain 850 000 O 873 800 O M1 0 008 M2 0 005 M1 M2 tY Start virtual CE G yBa250K d Bias tee Tektronix Part Number 015 0718 00 or
9. e the smaller better the distance resolution is When no frequency selective components such as antennas bias tees or TMAs are present and a 50 Ohm load is on the far end of the antenna feed DITF technology can work at its best and most accurate When antennas bias tees and TMAs are present two options exist First the DIF sweep can still be made over a wide frequency as in the ideal case mentioned above In this case frequencies outside the pass band of the components will be swept The return loss of the components will be artificially high but the distance resolution of the measurement will be preserved Second the DIF sweep can be made over a reduced frequency range This will allow the measurement to be made with greater return loss accuracy but with less distance resolution As an example of frequency selective equipment the Bias tees normally used for TMA installations may be frequency selective and may contain a 1 4 wave shorting stub for lightning The narrower bandwidth bias tees may limit the distance resolution of the DTF To perform a DIF measurement under ideal conditions and obtain the most accurate results gt Remove all frequency selective components and terminate the end of transmission line system feed line jumpers and connectors with a 50 Ohm load This will allow the best and most accurate measurements to be made gt Select Distance To Fault measurement gt Perform a one por
10. e very low return loss of the duplexer at those frequencies which dominates the overall antenna system performance Testing Antenna Systems with Tower Mounted Amplifier 444 900 00 Mez MPS EIA 553 ERAAN Chan 820 00 Measurement Method Calibration Return Loss Fast Liser _Calbration A g x Auto Scale Trace 1 Normal tc 6 00 l 1 indy Y 0 00 3 3 3 ae 6 00 Sy i aki 12 00 z 18 00 a 24 00 30 00 Stop MHz 36 00 42 00 200 00 E 48 00 54 00 7 i O e2000 860 00 MHz 900 00 4 934 800 oeo 30 800 A 832 800 VY 820 000 MHz gt Mi 8 765 Mm2_ 5 226 m1 m2 3 538 Max 19 749 Min 3 728 dB gt Figure 4c LNA bypassed Blue failure Yellow Antenna Keeping the LNA OFF and the bypass relay closed you can then simulate a severe failure by disconnecting the Yagi antenna and measure again Figure 4c illustrates how much lower the return loss within the Rx and Tx bands is blue line On the Rx band the resulting return loss is slightly better because it is also affected by the LNA output and the bypass characteristics You can now reconnect the antenna turn the LNA on and measure once more Figure 4d shows both antenna systems the blue line measures when the LNA is ON and the yellow line when the LNA is bypassed Even though the performance of the antenna system in the Rx side changes in shape it is still grea
11. ed to amplify the weak uplink signal There are several configurations depending on the BTS requirements the most common are Received only or simplex configuration S Single duplex configuration D Dual Duplex configuration DD These configurations are illustrated in Figure 2 Received only or simplex configuration S This configuration is used in antenna systems that have separate Rx and IX antennas and separate Rx and TX feed lines to the BTS The TMA is connected to the Rx antenna at the antenna port and to the BTS at the BTS port Single duplex configuration D This configuration is used in antenna systems that have a common Rx Tx antenna and separate Rx and Tx feed lines to the BTS A single duplexer isolates the receiver and transmitter path from the Rx Tx antenna The TMA is connected to the Rx Tx antenna at the antenna port and to the BTS at the BTS port Dual duplex configuration DD This configuration is used in antenna systems that have a common Rx Tx antenna as well as a common Rx Tx feed line as shown in Figure 1 The duplexers isolate the receiver and transmitter paths from the Rx Tx antenna and the Rx Tx feed line reducing the amount of antennas and feed lines in the system The TMA is connected to the Rx Tx antenna at the antenna port and to the BTS at the BTS port All three configurations have a Low Noise Amplifier LNA in the uplink path A bias tee injects DC voltage from the
12. equivalent BNC to DC adapter Tektronix Part Number 012 1686 00 or equivalent Test procedure gt Prepare the YBA250 YBT250 to perform two port measurements for a TMA Set up the cabling as shown in the Normalization section of Figure 5b gt Select Insertion Gain Loss button and Insertion Gain measurement type The default output power level is 20 dBm Check the manufacturer s gain specification to make sure the power at the RF INPUT YBT250 will not exceed its maximum value If it might exceed the maximum you can change lower the output power level gt Select frequency range appropriate to the TMA gt Perform a User Normalization following the wizard s instruction Make sure not to apply DC power to the bias tee during normalization gt Measurements immediately after normalization will display reference trace at O dB as shown in Figure 5a gt Disconnect the through connector and connect the TMA as shown in Figure 5b gt Apply DC power to the DC port of the bias tee gt Perform Insertion Gain measurement and press Auto Scale Systems with Tower Mounted Amplifier gt Application Note Normalization TMA S D DD __ Through connector BTS ANT Test cables Bias tee 10 dB __ __ Attenuators gt Figure 5b Normalization and Measurement Setups OMA US Cellular 7 Ve Ve ve Chan je22 00 Measurement Method Insertion
13. ers before using the NetTek analyzer to transmit a test signal When the Tower Mounted Amplifier is already mounted to the tower you can only measure its relative gain as opposed to the absolute gain value as described in previous section The purpose of this test is to verify that the TMA is working properly The relative gain is obtained by comparing the signal change at the BTS when the amplifier is ON and when it is bypassed For this test you may use the bias tee and the DC power supply from the PDU already in your system The key point for this test setup is to transmit the test RF signal up to the TMA within the Rx frequency band There are several options to accomplish this and some of them are Use a directional antenna as the Ix antenna at ground level pointing the Tx Rx antenna where the TMA under test is mounted Use an available Tx antenna mounted in the tower Test procedure gt Setup YBA250 two port measurement Select to Insertion Gain measurement type Setup frequency parameters according to the Rx frequency range of the TMA Verify the output power level is in compliance with transmission regulations Adjust the level if necessary 8 www tektronix com wireless TMA BTS ANT Tx antenna RF amp DC gt Figure 6a TMA testing when using a directional antenna gt Using a YBAC2 or equivalent normalization kit perform a User Normalization following the wizard s setup and
14. f their respective companies 1 05 FLG WOW 2EW 18514 0 Tektronix Enabling Innovation
15. instructions gt f using a directional antenna you may use a setup as illustrated in Figure 6a Connect the 10 dB attenuator at TEST PORT YBT250 to the directional Tx antenna Secure the antenna to make the signal path as constant as possible during the test Testing Antenna Systems with Tower Mounted Amplifier gt If using a transmit antenna on the tower set up as illustrated in Figure 7 When using a Tx antenna that is mounted at the tower you might need to increase the output power level to counteract the isolation between antennas Make the antenna a YAGI pointing at the tower gt Connect the 10 dB attenuator at RF INPUT YBT250 to the coax from antenna gt Bypass the LNA by removing DC power and make the insertion gain measurement Save trace File gt Save gt Filename gt Turn ON LNA by connecting DC power and make insertion gain measurement You may make several sweeps to ensure that the TMA is being powered on gt Using the dual trace capability of the NetTek analyzer display both traces on the same screen Edit gt Insertion Tab gt Gain gt View Trace 2 gt Filename gt You can view marker M1 on trace 1 View gt Marker 1 gt Trace1 and market M2 on trace 2 View gt Marker 2 gt Trace 2 Then you can use the M1 M2 indicator to obtain the relative gain For more details on how to work with traces refer to the YBA250 User Manual Figure 6b shows the relative gain re
16. ountry s laws regarding transmitters before using the NetTek analyzer to transmit a test signal Antenna to antenna isolation becomes more important as more antennas are located on a common tower The easiest method of improving isolation by increasing the distance from each other is limited Even though antennas in different sectors are pointing to different directions signals that are transmitted from one sector can also be received at another sector This is also known as co channel or co band interference The lower the isolation between antennas the greater the potential of interference signals at the receiver The basic setup to measure antenna Isolation is similar to the one illustrated in Figure 8 Test procedure gt Setup YBA250 two port measurement Select to Insertion Loss measurement type and setup frequency parameters to cover Rx and Tx frequencies gt Perform a two port normalization following the wizard instructions 10 www tektronix com wireless BTS ANT gt Figure 7 Installed TMA testing when using a transmit antenna Testing Antenna Systems with Tower Mounted Amplifier gt Connect the 10 dB attenuator at TEST PORT YBT250 to the Tx antenna s coax gt Connect the 10 dB attenuator at RF INPUT YBT250 to the Rx antenna s coax gt Make insertion loss measurement Press Auto Scale The insertion loss measured at the Rx band is the amount in dB that a signal sen
17. power distribution unit PDU through the center conductor of the feed line A second bias tee gt Application Note JASN DC DC RF RF BTS BTS BTS Receiver only or simplex Single duplex Dual duplex gt Figure 2 Typical internal TMA configurations within the TMA separates the DC voltage and the RF signal The TMA might also have circuitry to bypass the LNA when no DC power is detected This is used in case of TMA malfunctioning or as an emergency bypass The provision of the bypass circuitry is essential when sweeping the Rx band of the antenna and to measure the relative gain on mounted amplifiers Configurations of TMAs are sometimes illustrated using Rx and Tx filters instead of duplexers The overall operation is the same Duplexers and filters are frequency selected devices They pass signals with very little loss inside its frequency bands while attenuating all signals outside its bands A duplexer isolates the receiver and transmitter signal paths www tektronix com wireless 3 Testing Antenna Systems with Tower Mounted Amplifier gt Application Note RF signal at Tx frequencies only RF signal at Rx and Tx frequencies RF signal at Tx frequencies RF signal at Tx frequencies RF signal at Rx RF signal at Rx c frequencies frequencies RF OCc gt Figure 3 AF Signal path with and without bypass Importance of the Bypass Circuitry When Testing Antenna Systems
18. sult for a similar setup as of Figure 6a Each trace represents the total gain or loss which includes loss of cables and path gt Application Note CDMA US Celular 25 15 42 gt A chan 825 00 4 8 to 849 00 ajma biscerataules ll Te ae ae Insertion Gan High Resolution x Auto Scale Trace 2 Saved 0000C dy Bi ie H i Stop MHz 51 00 i nm 835 00 542 00 MHz 842 00 a 8 z Output Power Level Avg Insertion Gain STEER o dam 841 500 o 0 000 Y 877 900 822 100 MHz Mi 14 576 M2___ 29 114 M1 m2 14 538 Max 24 933 Min 73 144 dB gt Figure 6b Relative gain measurement result The yellow trace is the total gain loss when the LNA is bypassed and the blue trace is the total gain loss when the LNA is ON since both measurements are performed using the same signal path except at the LNA the difference between trace 1 and trace 2 at Rx frequencies gives approximately the gain of the LNA minus the loss of bypass circuitry This result is approximately 14 5 dB in Our setup It s interesting to Know that the measurement when the LNA is bypassed actually is the antenna isolation measurement There are more details on this in the next section www tektronix com wireless 9 Testing Antenna Systems with Tower Mounted Amplifier gt Application Note Measuring Antenna to Antenna isolation Caution Please check your c
19. t User Calibration at the end of the precision test jumper 6 www tektronix com wireless gt Connect precision test jumper to the feed line or the jumper in your system before the feed line gt Setup DIF measurements using the Distance Options setup page Edit gt Distance Option Select Cover Distance and set the distance to somewhat longer than the feed line gt Perform measurement Press Auto Scale If under these conditions the DIF measures a healthy system high return loss for connectors jumpers and feed line any problems may be due to the TMA To perform measurements with frequency selective components in place the procedure is similar but instead of selecting Cover Distance in the procedure above select Limit Bandwidth and set the band width as wide as possible given the components installed In the case that a TMA Is present you likely will need to cover only the uplink or downlink frequency band Also make sure that the TMA is in bypass mode Limiting the frequency of the sweep will reduce the distance and return loss accuracy but can give a useful indication of the health of your antenna system particularly when compared to other similar antenna systems Testing Tower Mounted Amplifier before Installation In previous sections we described the use and advan tages of antennas with Tower Mounted Amplifier You learned what to consider when testing such antenna systems the effe
20. t by the transmitter at Tx antenna side is reduced by before interfering in the receiver at Rx antenna side Conclusion Tower Mounted Amplifiers TMA and Masthead Amplifiers MHA are playing a key role In order to maximize the sensitivity of the receiver link This enables antennas to receive even weak signals extends the coverage area and helps to reduce the number of dropped calls To ensure the proper func tionality there is the clear need to test such systems as well as the TMAs themselves The Tektronix YBA250 and YBT250 with is Insertion Gain Insertion Loss measurement capabilities are perfectly equipped to meet these needs To find out more about other measurement functionalities application notes or technical briefs please visit www tektronix com wireless gt Application Note Rx F Isolation insertion loss gt Figure 8 Antenna isolation measurement www tektronix com wireless 11 Contact Tektronix ASEAN Australasia Pakistan 65 6356 3900 Austria 41 52 675 3777 Balkan Israel South Africa and other ISE Countries 41 52 675 3777 Belgium 07 81 60166 Brazil amp South America 55 11 3741 8360 Canada 1 800 661 5625 Central Europe amp Greece 41 52 675 3777 Central East Europe Ukraine and Baltics 41 52 675 3777 Denmark 80 88 1401 Finland 41 52 675 3777 France amp North Africa 33 0 1 69 81 81 Germany 49 221 94 77 400 Hong
21. ter than 18 dB Changes are more noticeable on the edges outside the Rx band which is due to the different transient properties of the LNA and the duplexer Keeping the LNA ON you can simulate a severe failure by disconnecting the antenna Figure 4e shows that the degradation on the Rx side is not nearly as severe as the degradation in the Tx side This confirms that when the LNA is ON the YBA250 does not see the antenna but rather sees the output impedance of the LNA gt Application Note AMPS EIA 553 welis ke Chan 820 00 iiil to 900 00 EH MHz Measurement Method User Calibration paT Trace 1 Normal x EE Return Loss Fast x Auto Scale 6 00 0 00 band 12 00 4 fo f 8 19 00 24 00 30 00 36 00 42 00 48 00 54 00 4 k 820 00 gt 8348000 848 800 0 1 33 024 m2 30 568 Mi M2 gt Figure 4d Blue LNA ON Yellow LNA bypassed 860 00 MHz 900 00 4 H 14 000 A 840 800 VY 820 000 MHz 2 456 Max 44 090 Min 3 739 dB AMPS EIA553 v Hisli E Chan 820 00 33 to 200 00 ipj MHz Measurement Method l User Calibration Return Loss Fast x EA x Auto Scale Trace 1 Normal 7 Fa S dy Y 6 00 r 1 0 00 3 IPAR 6 00 a 3 a eee bg 12 00 3 3 re 7 Vat 18 00 M2 24 00 SON 848 800 i 30 00 36 00 42 00 48 00 _
22. ut from one of the components of the TMA Because of this it is important to understand the TMA s configuration and basic operation to properly test antennas with TMA The inclusion of a TMA not only introduces new challenges when testing antenna systems but also introduces the need to test the TMA itself The YBA250 offers Insertion Gain Loss measurement that in conjunction with the YBT250 suits this need Insertion Loss measurement can also be used to perform antenna to antenna isolation measurements which is becoming more important as more antennas are located on one tower 2 www tektronix com wireless Antenna A Jumper E amp 2 Transmission line feeder feed line oO Possible Test point YBA250 BTS House Bias Tee Note for simplicity this graphics shows only one sector gt Figure 1 Antenna system with TMA In this application note you will first learn about typical configurations of tower mounted amplifiers the role of bias tees and duplexers as well as the effects that amplifiers and filters have on reflection measurements We will then describe the procedure to sweep antennas with TMAs and how to properly use the distance to fault measurement DTF to locate faults Then we will move to specific gain measurements of tower mounted amplifiers and antenna isolation using two port measurements Testing Antenna Systems with Tower Mounted Amplifier Common TMA Configurations A TMA or HMA is us
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