APM-16射频功率表|射频功率计
Average-Reading Portable Wattmeter
Designed especially for RF power measurement in PCS, cellular,
ESMR, paging and similar communication systems
Equally effective for measuring RF power in conventional analog
systems
Uses APM-series plug-in elements to cover a wide range of frequency
and power levels. Simple Thruline® style operation for instant
forward or reflected power readings
Interchangeable QC connectors for fast hook-up
The Model APM-16 RF wattmeter is designed to keep pace with the
ever growing complexity of digitally-based communication systems.
Bird's Model 43 and most other wattcmeters available today were
designed to measure power of constant amplitude, sinusoidal
waveforms. Modern wireless communication systems can use a variety
of digital techniques to combine many voice data channels into a
complex, composite RF signal. Measurement of such signals with a
conventional wattmeter may yield unacceptable errors. The APM-16
employs active circuitry to deliver accuracy of ± 5% for
multiple-access technologies such as CDMA, TDMA, FDMA and other
digitally-encoded communication systems.
| Accuracy:
| 10° to 35° C ±4% reading, ±1% full scale,
–20° to 50° C ±6% reading, ±2% full scale
|
| Battery:
| Internal 9 volt
|
| Connector:
| QC type (Female N normally
supplied)
|
| Frequency Range:
| 2 MHz to 2.3 GHz
|
| Humidity:
| 95% ±5% max. (noncondensing)
|
| Insertion VSWR:
| (with N connector) 1.05 max. to 1000
MHz
|
| Meter:
| Shock mounted, linear scale with expanded
scales of 25, 50 and 100 for full scale 1 to 1000 W readings.
Mirrored scale includes 5% overrange.
|
| Nominal Size:
| 6 7/8" H x 5 1/8" W x 3 5/8" D, (175 mm x
130 mm x 92 mm)
|
| Peak/Average Ratio:
| In excess of 10 dB
|
| Power Range:
| 1 W to 1000 W
|
| Setting Time:
| < 1 second
|
| Temperature Range:
| –20° to 50° C operating; –25° to 65° C
storage
|
| Weight:
| 3 lbs. (1.4 kg) |
APM-16射频功率表|射频功率计探头选型表
| APM-16 Elements - 7/8" Line
Section
|
|
|
Frequency
Bands (MHz)
|
|
Power
Range
|
2-30
|
25-60
|
50-125
|
100-250
|
200-500
|
400-1000
|
950-1260
|
1100-1800
|
1700-1990
|
1990-2200
|
2000-2300
|
|
1
W
|
-
|
-
|
APM-1B
|
APM-1C
|
-
|
APM-1E
|
APM-1J
|
-
|
APM-1L1
|
APM-1L2
|
APM-1M
|
|
2.5
W
|
-
|
-
|
APM-2.5B
|
-
|
APM--2.5D
|
APM-2.5E
|
APM-2.5J
|
APM-2.5K
|
APM-2.5L1
|
APM-2.5L2
|
-
|
|
5
W
|
APM-5H
|
APM-5A
|
APM-5B
|
APM-5C
|
APM-5D
|
APM-5E
|
APM-5J
|
APM-5K
|
APM-5L1
|
APM-5L2
|
-
|
|
10
W
|
APM-10H
|
APM-10A
|
APM-10B
|
APM-10C
|
APM-10D
|
APM-10E
|
APM-10J
|
APM-10K
|
APM-10L1
|
APM-10L2
|
-
|
|
25
W
|
-
|
-
|
APM-25B
|
APM-25C
|
APM-25D
|
APM-25E
|
-
|
APM-25K
|
APM-25L1
|
APM-25L2
|
-
|
|
50
W
|
-
|
-
|
-
|
APM-50C
|
APM-50D
|
APM-50E
|
APM-50J
|
APM-50K
|
APM-50L1
|
APM-50L2
|
-
|
|
100
W
|
APM-100H
|
APM-100A
|
APM-100B
|
APM-100C
|
APM-100D
|
APM-100E
|
APM-100J
|
-
|
APM-100L1
|
-
|
-
|
|
250
W
|
APM-250H
|
APM-250A
|
APM-250B
|
APM-250C
|
APM-250D
|
APM-250E
|
-
|
-
|
-
|
-
|
-
|
|
500
W
|
APM-500H
|
_
|
APM-500B
|
APM-500C
|
APM-500D
|
APM-500E
|
-
|
-
|
-
|
-
|
-
|
|
1000
W
|
APM-1000H
|
_
|
APM-1000B
|
APM-1000C
|
_
|
APM-1000E
|
-
|
-
|
-
|
-
|
- |
APM-16射频功率表|射频功率计|产品说明书下载
如何使用驻波比表
BV3FG 若以功率的观点来看 驻波比可以表示为：
SWR = (√Po + √Pr)／(√Po - √Pr)
Po：进入天线系统的功率 Pr:从天线系统反射回来的功率
经过运算 SWR 与 Pr/Po (反射功率百分比)的关系如下：
Pr/Po = [(SWR-1)/(SWR+1)]^2
驻波比表基本上就是功率表。它可以量测输入功率及反射功率。但根据上式，不管输入功率为何，反射功率一定和输入功率成一定的比例。也就是说，对同一驻波比，不管输入功率为何，只要是在量输入功率时利用可变电阻调整驱动表头的电流使指针达到满刻度。那麽你量测反射功率时，指针一定是指在同一个位置。把这些相关位置标出来，我们的功率表上就多了一排刻度，叫做"驻波比"，而您的功率表马上摇身一变成为"驻波比表"了。
说穿了，驻波比表就是功率表。在量测功率时它预设了几组功率(如5W,20W,200W)使输入功率恰好是这个位准时(5W, 20W,
200W)，指针会达到满刻度。当你拨在CAL位置时就是量输入功率，只不过你可以调整指针位置。当你拨在SWR位置时就是量反射功率，只不过您这时候看的是SWR的刻度。
以DIAMOND系列的驻波比表而言，它有一个 Calibration 旋钮及三个选择开关：Power
Range，Func，FWD/REF SWITCH。用法如下。
量输入功率：
1.将 POWER RANGE 拨到200W，FUNC 拨到PWR，FWD/REF 拨到FWD；
2.按下无线电机的发射键；
3.适度选择 POWER RANGE 以精确读出功率。
量反射功率：
1.将 POWER RANGE 拨到200W， FUNC 拨到PWR， FWD/REF 拨到REF；
2.按下无线电机的发射键；
3.适度选择 POWER RANGE 以精确读出功率。
量驻波比：
1.将 FUNC 拨到CAL 位置，CALIBRATION 旋钮反时针方向旋转到底；
2.按下无线电机的发射键，调整 CALIBRATION旋钮使指针达到满刻度；
3.将 FUNC 拨到 SWR 位置，由表头的 SWR 刻度读出驻波比的读值。
使用驻波比表量测天线的驻波比时要尽量将驻波比表靠近天线端，因为传输线的传输损耗会使得所量出来的驻波比数值较小，变成
"快乐驻波比"。例如，原本天线的驻波比为 1.92 (反射功率百分比为10%)，现在加上一段 cable 衰减量为
3dB，假设无线电机的发射功率为10W，则经由 CABLE 传到天线的输入端时只剩下5W，然後反射10% 即 0.5W，0.5W
经由传输线送回来只剩下0.25W，所以驻波比量到的是输入 10W，反射 0.25W，反射功率百分比为 2.5%，即 SWR=1.03
量起来真是快乐的不得了。
此外，目前大部份的驻波比表都是利用感应的方式将信号感应到驻波比表内的量测电路，所以在量测时可以一边发射一边切换驻波比表上的开关，这并不会损坏无线电机。如果小心一点，不要让指针瞬间打到底。驻波比表要坏掉也蛮难的。
最後提醒一点，天线的好坏不能单看驻波比。现在大家如此迷信驻波比的原因很简单，因为驻波比表到处都买得到。我的意思是说，不要因为天线驻波比很低就觉得一切OK而沾沾自喜，多研究天线的其它特性才是真正的乐趣.
美国鸟牌（Bird）射频功率计（RF功率表）选型一览
|
功率计型号
| 43
| 4304A
| 4391A
| 4410
| APM16
| 4305
| 4431
| 4314B
| 4308
| 5000/5010
|
| 频率段（MHz）
| 功率段
|
|
| 2-30
| 50W-10KW
| √
| √
| √
| √
| √
| √
| √
| √
|
| √
|
| 25-60
| 50W-1KW
| √
| √
| √
| √
| √
|
| √
| √
|
| √
|
| 50-125
| 25W-1KW
| √
| √
| √
| √
| √
|
| √
| √
|
| √
|
| 100-250
| 25W-1KW
| √
| √
| √
| √
| √
|
| √
| √
|
| √
|
| 200-500
| 25W-500W
| √
| √
| √
| √
| √
|
| √
| √
| √
| √
|
| 400-960
| 10W-500W
| √
| √
| √
| √
| √
|
| √
| √
|
| √
|
| 950-1260
| 5W-250W
| √
|
| √
| √
| √
|
| √
| √
|
| √
|
| 1100-1800
| 1W-50W
| √
|
| √
| √
| √
|
| √
| √
|
| √
|
| 1700-1990
| 1W-50W
|
|
|
|
| √
|
|
|
|
| √
|
| 1990-2200
| 1W-50W
|
|
|
|
| √
|
|
|
| √
| √
|
| 2200-2300
| 1W-25W
|
|
|
|
| √
|
|
|
|
| √
|
| 2400-2500
| 1W-25W
|
|
|
|
| √
|
|
|
|
| √
|
| 2600-2700
| 1W-25W
|
|
|
|
| √
|
|
|
|
| √
|
| 3400-3500
| 1W-10W
|
|
|
|
| √
|
|
|
|
| √
|
| 3500-3600
| 1W-10W
|
|
|
|
| √
|
|
|
|
| √ |