KA7U 1 Meter Active Loop

KA7U receive loop antenna, active loop antenna

Coax Loop with differential amplifier.

Outdoor Utility box.

LNA mounted in box

LNA & Balun/Power inserter boards.


This RECEIVE ONLY antenna comes with 100 feet of outdoor rated CAT6 F.P.A. cable, terminated in RJ45 Jacks. A LNA and 2:1 balun with a power inserter, an RJ45 input and a BNC output board is also included. If you need more than 100 feet of cable, add 20 cents a foot for the overage at checkout. Or if you need less cable, deduct 20 cents a foot at checkout.

A user provided BNC cable connects to the Balun/Power Board to your receiver. The supplied FPA cable connects to the Balun/Power Board, and a user supplied 12-14VDC power source connects to the power plug. A demo of this antenna is providing signals to a websdr which can be listened to @ http://ka7u.no-ip.org:8074 .

Shipping is included to the United States. Postage elsewhere will be quoted at time of order.

The antenna is made from RG213/U coax cable, the vertical supports are 1/2″ schedule 40 PVC water pipe, and the box containing the amplifier is a plastic outdoor electrical box.  The amplifier board is not encased in epoxy and is user accessible.

This is a great antenna for shortwave listening and diversity reception for Ham radio enthusiasts. It works very well with SDR radios and covers from DC through 30MHz. The antenna is broadband and does not require tuning or other adjustment to use.

The antennas are custom made by K7RHB and KA7U, so if you have special requirements, feel free to ask and we might be able to adjust it for you.

Please use the contact form for questions and inquiries.

Differential LNA

LNA & Balun/Power inserter boards.


Differential amplifier and balun/power inserter board, RJ45 to BNC to interface 4 pair cable to coax. 100 ohms to 50 ohms.

This amplifier is designed to be used with a 1 meter loop antenna. It works well from DC to 30MHz. It uses 12 to 14vdc power. The transistors have been matched for performance in each stage to obtain a good differential effect, reducing common mode noise. This combination provides a shielded RJ45 on the balun board to ground the FPA cable shield at the receiver, but the RJ45 is not grounding the shield at the LNA. This is usually the best configuration to reduce common mode currents in the system. The antenna input is diode limited to 0.7v and has VHF/UHF filtering to help protect the amplifier from very strong signals and static noise.

This Differential LNA is providing signals to a websdr using a 1 meter loop antenna like the one advertised elsewhere on this site. You can listen to the websdr to evaluate the amplifier @ http://ka7u.no-ip.org:8074

These boards are custom made by K7RHB and KA7U. You can ask about having specific things concerning these amplifiers and we may be able to adjust the circuits to your needs.

Free shipping within the U.S.A. Please contact for a shipping quote outside of the U.S.A.