Wellbrook Communications

Wellbrook Communications

The Wellbrook K9AY directional terminated Loop antenna for long and medium wave.


The K9AY Directional Terminated Loop Antenna is a totally new receiving Antenna System designed to improved Long and Medium wave reception.

The Wellbrook antenna provides a cardioid reception pattern with up to 30dB front-to-back ratio over a very large bandwidth. The antenna uses two Delta Loops with a reversible beam direction to provide a 360 degree coverage.

A unique feature of the K9AY, is the Remote Controlled Variable Termination. This allows the user to optimise the null during changes in the arrival angle of interfering signals and provides a considerable improvement in reception quality.

The K9AY is specifically designed to simplify the construction of this Loop antenna. The K9AY comprises of two assemblies: Antenna Control Unit, and an Antenna Head Unit.

K9AY Antenna Control Unit
K9AY Antenna Control Unit - Null and Direction knobs are at the front, with the sockets for the p.s.u. and receiver output at the side.

The Antenna Control Unit provides the antenna control functions, supplies the power to the Antenna Head Unit, and feeds the signal to the receiver. A 10-15dB Broadband Amplifier is fitted. The Antenna Head Unit provides the variable antenna termination, Beam Reversal and the Loop selection electronics. Integrated into the Antenna Head Unit is a 9:1 Balun. This Balun has the feeder winding isolated from the antenna so that the antenna is magnetically coupled to the feeder. This reduces antenna/feeder interaction and mains borne noise from TVs, computers etc.

The K9AY antenna uses a coaxial feeder cable without an antenna tuner. Low noise performance is assured because there is no antenna return path to mains earth. The K9AY, is also suitable for non-directional short wave reception and will provide far lower noise performance (similar to the T2FD) than an equivalent length Longwire antenna. The electronics are encapsulated in synthetic resin to form a weather proof construction.

Comprehensive operating and installation instructions guide the user to a easy and safe erection. The K9AY is supplied complete with an Antenna Control Unit, Antenna Head Unit. To operate the K9AY, the user must provide a 12volt regulated Power Supply (included for UK users only), antennna wire, the 50 ohm feeder cable and the twin lead control wire.

Wellbrook Communications K9AY Control Unit
K9AY Antenna Control Unit


· Up to 30dB F/B ratio 60kHz to 2MHz · Lower noise than Longwire
· 2 Loops for 360 degree coverage · Coaxial feeder reduces local noise
· Variable Null depth control · Static discharge path to earth
· Rotary beam direction control · Low noise 10-15dB amplifier
· Omni-directional up to 30MHz · Weather proof construction


This antenna was originally designed in the US by a radio amateur, Gary Breed - K9AY, and has been used successfully used by radio amateurs and medium wave listeners.

The unique feature of the K9AY is the constant high front to back ratio over a very large bandwidth. The K9AY is probably the only medium size passive antenna that can provide a significant improvement to medium and long wave reception.

The antenna simply requires up to two 25m wire Loops. A single 8m vertical support is required such as a tree. However, it is important that the antenna is erected away from buildings and sources of interference. The K9AY only requires an area of 9m x 9m to complete the erection. Thus, it will fit into most gardens.

K9AY Antenna Head Unit
K9AY Antenna Head Unit - interface between the loops and the control unit.

Feeder: Up to 50m of RG58 coaxial cable can be used with the K9AY.

The feeder connector should be wrapped with self-amalgamating tape to make the connection waterproof.

WARNING: The K9AY must not be used with a transmitter or a transceiver.
Do not allow the antenna into contact with overhead power lines.
Take extra care to avoid injury when erecting antennas.



Now read: John Wilson's Review in Short Wave Magazine

Wellbrook Communications
The Farthings
Llanwrtyd Wells
Wales LD5 4YD
Phone 01591 620316

Specialists in Broadband Loop Technology!


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Designs and specifications are subject to change without notice

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