ET plus Antenna Amplifier 03/20/06

Transcription

1 INSTALLATION TIP: CB_ ET plus Antenna Amplifier 03/20/06 Products: Versions: ET plus Series 9,12, 18 & 24 stations All Software Versions Overview This Installation Tip identifies how to install an antenna remotely from a controller and how a single antenna can be shared by two ET plus units. Application In applications where the antenna needs to be mounted at a distance from the controller, the signal strength drop due to the coax cable used may prevent consistent communication with the controller. A way of countering the loss is to install an amplifier to amplify the signal before sending it down the cable. Examples of where this application might occur is when controllers are located in concrete reinforced parking garages or deep within basements where an externally mounted bow tie or similar antenna does not provide sufficient phase integrities. The solution discussed below works for a single controller connected to a single antenna and two Plus controllers connected to a single antenna. Solutions Amplifier Only 1. Place an amplifier in-line between the controller and the antenna at the antenna end of the cable. You can purchase an antenna amplifier (model AMP-900/23 M) for $250 at (See Figure 1 for picture of amplifier).! Note: This is presently not a service kit and serves merely as one possible solution for the applications noted on page one. 2. It is possible the mating ends of the amplifier may not be the same as the SMA connector or TNC connectors found on HPDS antenna cabling. In these cases you may need to purchase and additional cable adapter one such adapter is shown in Figure 1 below. CB_ ET plus Antenna Amplifier 1

2 Figure 1 Cable Gender Adapter TNC to BNC You may need to purchase several of these adapters depending on the installation. RG58 antenna cable provides the best performance. A local radio shop can make custom cable lengths with the specific adapters as needed. Figure 2 below shows an amplifier with a RG58 antenna cable. Figure 2 Amplifier and the roll of cable! Note: The output of an amplifier is power plug end of this device. CB_ ET plus Antenna Amplifier 2

3 Amplifier with Two (qty) ET Plus Controllers 1. Place an amplifier in-line between the controller and the antenna. You may need to purchase antenna cable adapters depending on the model of amplifier purchased. 2. Add a splitter downstream from the amplifier. (See Figure 3 for a picture of the splitter.) Again depending on the splitter connections, additional adapters may need to be purchased. Figure 3. Splitter The splitter comes from Mini-circuits and costs around $62 and the model number is ZFM-4 ( Test Results of Amplifying the Antenna The amplifier noted above was tested in the following manner: A WeatherTRAK ET plus controller was connected to an antenna via a short coax cable and the phase integrity numbers recorded. The amplifier was then inserted in the lines, making sure the lengths of the lines did not change, and the integrity numbers again recorded. The following table depicts results of this configuration: External antenna no amplifier External antenna no amplifier Average Signal Strength With Antenna Amplifier CB_ ET plus Antenna Amplifier 3

4 With Antenna Amplifier Average Signal Strength 24% 56% 109% % Improvement Amplifier and Coax Cable Test Next a 50 foot length of RG59/U cable was used between the antenna and the WeatherTRAK ETplus controller. The amplifier was then inserted. RG59/U cable is 50 ohm inexpensive coaxial cable with a loss of about 14.4 db per 100 feet. For 50 feet this gives a loss of 7.2 db. The results were: External Antenna w/ 50 of RGB59 cable External Antenna w/ 50 of RGB59 cable Average Signal Strength External Antenna w/ 50 of RGB59 cable External Antenna w/ 50 of RGB59 cable External Antenna w/ 50 of RGB59 cable Average Signal Strength 159% 73% 100% Improvement in % Test results indicate the amplifier brought the phase integrities way up to acceptable levels for signal reception. Two Controllers Sharing One Antenna Next we tested a Mini Circuits ZFSC-2-4 splitter to see the effect of running two controllers off the same antenna. The splitter was located next to the controllers. 50 feet of the RG59/U was between the splitter and the antenna amplifier. The results were: Controller Type WT plus 9/ Splitter, no amplifier & 50 ft. of cable WT plus 18/ CB_ ET plus Antenna Amplifier 4

5 WT plus 9/ No splitter, no amplifier 0.00% 0.00% 18.75% Splitter Effect in % WT plus 9/ Splitter & 50 ft. of cable WT plus 18/ % 81% 56% Improvement in % Test results indicate the splitter had a small effect at the lower signal levels but no effect at the higher strengths. Adding the amplifier caused considerable improvement in signal strength. It is interesting to note the improvement was even more than the case without the splitter. This is probably caused by a better impedance match of the cable to the controller caused by the splitter addition. Conclusions The RF links AMP-900/23 M model amplifier can easily overcome the signal reduction caused by 50 feet of low grade RG59/U cable. Based on the numbers it would work on 100 feet of the cable. A splitter had little effect on signal strength except at low signal strengths. The amplifier and splitter combination with 50 feet of cable worked better than no cable or amplifier or splitter. For further assistance, contact WeatherTRAK s Customer Service, toll-free CB_ ET plus Antenna Amplifier 5