Cross Country Wireless Loop Antenna Amplifier ++
The Loop Antenna Amplifier ++ contains all the electronics needed for home DIY construction of an active loop (magnetic loop) low noise receiving antenna.
The amplifier consists of two units, a weatherproofed outdoor head unit for connection to a suitable loop and a bias tee unit to provide DC power up the coaxial cable to the outdoor unit. The head unit can also be used on it's own powered by the internal bias tee inside a SDRPlay receiver.
The outdoor unit is housed in a polycarbonate box with stainless steel antenna connections and a BNC socket. The bias tee unit is a PCB with two BNC connectors and a DC socket to take DC power from a battery or power supply.
Like our other active antenna products it has RF overload protection to allow it to be used very close to transmit antennas without damaging the amplifier or the attached receiver.
The loop depends on what the user has available. We have tested it with simple wire loops or deltas, coax loops and an alloy loop made from a bicycle wheel rim. We supply a 2.5 m (8 ft) length of wire as a simple loop to make a first loop for testing.
The photograph on the right shows the prototype with a 1m diameter loop of LDF4-50 coax cable as a test loop.
The standard version is the V4. We use this version in our HF Active Loop Antenna v4.
This now has a frequency range of 90 kHz to 55 MHz and is recommended for long wave, medium wave and HF use.
The Bias Tee unit is intended for use with a 12 V feed which allows the head unit amplifier to have a greater dynamic range than with the 5 V available from a SDRPlay receiver. The components in the internal bias tee inside a SDRPlay receiver limits the minimum frequency to 500 kHz. Using our bias tee unit allows the antenna amplifier to work over it's full range. This is ideal for fixed station operations with high quality loops and high performance base station receivers or transceivers.
Specifications:
Frequency range (Loop Antenna Amplifier ++ V4): 90 kHz to 55 MHz
Output impedance: 50 ohms
OIP2: >+70 dBm
OIP3: >+32.5 dBm
Gain (head and base units Loop Antenna Amplifier ++): 25 dB at 14 MHz
Noise figure: 0.79 dB
Supply voltage (head unit): 4.5 to 15V from a bias-tee feed via the coaxial cable
Supply current (head unit fed with 5 V from bias-tee ): 30 mA
Supply current (head unit fed with 13.8 V from bias-tee): 40 mA
Loop antenna outdoor unit connectors: Two M6 stainless steel threaded studs and BNC female (RF out 50 ohms)
Loop antenna amplifier bias tee board connections: BNC female (RF input and DC feed to outdoor unit), BNC female (RF output to receiver), DC connector (for 4.5 to 12 V DC power input)
We use eBay for our individual customers as they look after the import tax and fees involved in international transactions.
The eBay listing for the Loop Antenna Amplifier++ is here.
If the eBay listing is sold out we have a regular stock situation post on the Cross Country Wireless Groups.IO forum..
We also announce new batches of our products on the Groups.IO forum.
For our professional and commercial customers we now have a Wise.com account so we can accept bank transfers in local currencies worldwide.
Contact us for a quotation.
The Loop Antenna Amplifier ++ is also available from our authorised reseller SDR-Kits.
An early version of the Loop Antenna Amplifier was reviewed in the March and April 2020 issues of Radio User magazine.
Here is a ink to the review web page.
Here's a video of the prototype of the Loop Antenna Amplifier in use with a loop made out of a 700C bicycle wheel rim. The video is made during a field test in a very quiet rural environment. Watch the volume control during the early few seconds of the video due to wind noise on the camera phone used. It clears up later.
Contact Chris Moulding via info@crosscountrywireless.net