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Results of Testing the Antenna System at Duke Hospital (Emergency Department)
June 16, 2003
Dave Johnson, WA4NID
Current situation, and objective:
Currently we have a hardline feed terminated at the station location in a female N connector. This is patched to an ICOM 2700-H rig
(mic missing) with a short length of what looks like RG-58 equivalent (or similar), terminated in a PL-259 connector.
Actual antenna type is unknown to me. I wanted to do some quick checks of the
antenna system's condition.
What was done:
First, antenna analyzer was used to check the SWR pattern across the 2-meter band.
The antenna system is composed of hardline feed into the operating position in the police room in the ED. This is terminated in an "N" style connector. There is a short (couple of feet) patch cord that converts the "N" connector on the hardline to a PL-259 style connector. This PL-259 type connector is attached to the ICOM IC-2700H rig.
I set up an antenna analyzer and frequency counter so that measurements could be made of SWR across the 2-meter band.
Initially, it seemed there was not a broad flat SWR across the band. Instead, there were several sharper SWR dips within the band. Some data were recorded with the patch cord (below), then the patch cord was removed from the setup and the same pattern of sharp SWR minima was observed. The only difference noted with the patch cord removed from the system, was the slight shift in the minima downward a few KHz.
Note that these SWR measurements are not expected to provide data sufficient for a final determination on the health of the antenna system. But it provides some data to compare with future measurements. I RECOMMEND OTHER TESTING WITH ANOTHER SWR METER ALSO.
Here are the results with the antenna analyzer.
SWR over 2:1 except within these sharp dips:
SWR FREQ
2 148.18
1.5 147.99
1.2 147.828
1.19 147.79 LOWEST POINT IN THIS DIP
1.5 147.47
2 147.168
2 146.21
1.5 145.69 LOWEST POINT IN THIS DIP
2 145.12
Also a dip to 1.22 SWR at 142.048
The second phase of the testing involves using my Kenwood HT to try and hit the various area repeaters using the antenna system. Note that being able to bring up a repeater does not necessarily mean that we have a readable signal. It just means the repeater receiver can pick up our signal.
Output power levels that I could hit the repeaters with, using the antenna system at the Duke Hospital Emergency Department:
Repeater
(MHz) |
Power
(Watts) |
| 145.13 |
- |
| 145.23 |
5 |
| 145.39 |
- |
| 145.45 |
0.5 |
| 146.64 |
5 |
| 146.88 |
1 |
| 147.135 |
0.5 |
| 147.225 |
0.5 |
| 147.36 |
0.5 |
| 147.42 |
- |
| 442.15 |
1 |
| 443.275 |
5 |
| 443.425 |
1 |
| 443.475 |
0.5 |
| 443.625 |
5 |
| 444.1 |
0.5 |
| 444.45 |
5 |
| 444.525 |
5 |
| 444.575 |
0.5 |
| 444.675 |
5 |
| 444.925 |
0.5 |
Note that a result of "-" means I could not bring up the repeater using up to 5 watts output. A result of 5 means I could not key the repeater using 1 watt or less, and a result of 1 means I could key the repeater at 5 and 1 watts, but not 0.5 watt.
RESULTS SUMMARY:
Although this was not meant to be a comprehensive test, it does show that the antenna system at Duke Hospital seems to be functioning fairly well.
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