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New product ST940B covert half loop autotune HF antenna - RF Cafe Forums

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 Post subject: New product ST940B covert half loop autotune HF antenna
Posted: Tue Feb 07, 2006 6:30 am 
Tentative batch of 30nos of ST940B antenna system is released. System is developed by request of UN. Please address all comments to george@stealth.ae (Stealth Telecom Ltd.)


RMR assy...


antenna tuning units...


antenna remote control unit


main unit


stealth flyer



General Specifications ST-940B

Frequency Range 2.7 ? 15.0 MHz, ±2%

Power Rating 125 W PEP

Input Impedance 50 ohms

VSWR Not greater than 1.3:1

Pattern Radiation Omni directional, HRP offsets are less than 1 dB at two opposite minimas,

Vertical Elevation ? NVIS lobe @



(Measured at VSWR 2:1) 20 kHz at 3.0 MHz Carrier

260 kHz at 15.0 MHz Carrier


(compared to ideal 1/4? GP*) -0.32dB @ 15 MHz; -1.27dB @ 7 MHz;

-2.17dB @ 3.5 MHz;

Power Supply Voltage 12-14VDC/ 4 A (peak current)

Tuning Method Continuously Variable Tuning

Tuning Time 3 seconds average, 8 seconds max.

Tuning Accuracy ± 1.8º step or :

Approx. ±200 Hz at 3.0 MHz

Approx. ±15 kHz at 15 MHz

Tune Signal 4-30 W PEP CW followed by logic

consequence via 4 I/O programmable interface

Tuned Point Instability

Wind/Vibration Not detected at speeds up to 150 km/h

asphalt and up to 90 km/h off-road

Tuned Point Thermal Instability

(within 3 min under 100 W PEP CW) Less than 500Hz negative

drift @ frequencies below 4 MHz

Less than 10Hz negative drift @

frequencies above 4 MHz

Feeding method Shunt fed, ?-match in series with

preset reactance

System Serial Bus RS-485, differential

Programming Port RS-232

Dimensions H x W x L,

(without mounting brackets) Folded Up: 740** x 1254 x 1852 mm

Folded Down: 175 x 1254 x 1852 mm

Weight (without mounting brackets) 36 kg

Sealing Withstands rain testing per MIL STD 810 C/D/E

Shock/Vibration Protection provided via Impact

resistant vibroframe

Dust and Humidity Protection provided via environmental

resistant housing to MIL STD 810

C/D/E and connections to MIL C26482.

* If compared with mobile loaded whips approx. 0.6 dB to be added at all three frequencies.


Data is specified for +25Cº unless otherwise stated. All specifications listed are typical.

Specifications are subject to change without notice and are issued for guidance purpose only.

Posted  11/12/2012

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