Wellbrook CommunicationsWellbrook Communications

Active Loop Antenna ALA1530 for long wave, medium wave and short wave radio reception. This unique broadband magnetic antenna is only 1m diameter, rotatable and provides deep nulls to reject noise and interference. Ideal for users with small gardens...
50kHz to 30MHz
2007 - NEW DESIGN


ALA 1530 (OUTDOOR) and ALA 2000 (INDOOR) BROADBAND ACTIVE LOOP ANTENNAS 150kHz to 30Mhz

NEW ALA 1530+ Upgraded Version NEW

The ALA1530 is a compact Active magnetic loop antenna primarily designed to provide improved performance over conventional passive and active antennas. This loop has been production for over 10 years and has recently had significant design changes to improve LW and MW reception.

Active loop antennaThis Active loop sets new standards for the listener. For the first time it is possible to reject locally radiated and mains borne noise and still provide improved sensitivity compared to larger antennas.

1m dia. Aluminium loop is designed for outdoors, even at ground level. The loop has a frequency range from 40kHz to 30MHz and matches directly to the receiver. The ALA 1530 is probably the only Commercial Active antenna available to the Radio Enthusiast to provide directional reception of the LW and MW bands.

The loop can be mounted remotely from the receiver away from local interference. Whereas, traditional antennas require a lot of space and can pick-up local noise.

Supplied complete with Antenna Interface and a regulated power supply.

BROADBAND LOOP FEATURES

  • Very low intermodulation products ensures good performance in a strong signal environment
  • New design has much lower MW Intermod.
  • Up to 30dB rejection of locally radiated and power-line noise compared to an active whip
  • Figure of eight directivity and deep nulls to further reduce interference.
  • Ideal for LW/MW with antenna rotator
  • Rugged construction, 1m dia. aluminium loop,supplied with Antenna Interface and 12 volt PSU
  • No tuning necessary or matching unit
  • No planning problems, works at ground level

LOOP ANTENNA ADVANTAGES

Suitable for small gardensThe active antenna solves the problem of impedance matching to the feeder and yet the performance is comparable with larger antennas. However, most active antennas are the whip type and respond mainly to the electric-field. The Broadband Loop responds primarily to the magnetic-field, this ensures high rejection of nearby electric-fields.

The intensity of the electric-field is usually higher than the magnetic-field when an antenna is close to interference sources such as TVs florescent lamps, mains wiring etc. Therefore, by rejecting the electric-field there will be a reduction in local interference compared to other types of active and passive antennas. Interference reduction is further enhanced by the deep nulls of the 'Figure-of-Eight' directivity pattern.

INTERMODULATION

Some active antennas generate intermodulation products which can appear as spurious signals interfering with reception. This interference or second order intermodulation is caused by non-linearity in the amplifier, producing signals which are the usually the sum and difference of strong Broadcast stations.

The ALA 1530 Broadband Loop has been specifically designed to reduce intermodulation products to a minimum. The second order and the third order intercept points are typically +70dBm (IP2) and +40dBm (IP3) respectively. Thus the level of the intermodulation products are generally below the atmospheric and man made noise.

ANTENNA DESIGN

The Loop antenna consists of a rigid aluminium loop and a balanced gain optimised broadband amplifier using low noise RF power transistors. The amplifier is encapsulated in resin and housed in a uPVC box, this ensures reliable operation in all weather conditions. The antenna provides low noise performance, large signal handling ability. Rejection of mains borne noise is accomplished by using a balanced amplifier so that the feeder does form part of the antenna return path.

The ALA1530 is supplied Antenna Interface and a 12 volt regulated power supply. RG58C 50 ohm coaxial feeder cable is recommended for the antenna. The maximum feeder length is 100m. A 1m coax. lead connects the Antenna Interface to the receiver. A plastic loop version is available; the ALA1530P.

The ALA 1530 should be positioned approximately 5m away from any buildings.

TECHNICAL INFORMATION

Power consumption: 12 volts at 120mA
Intermodulation typically:
With two signals of 30mV
2nd order -104dB
3rd order -134dB
Intercept point typically:
2nd order +70dBm
3rd order +40dBm
1dB compression point: +25dBm
Output impedance: 50 ohms

NEW ALA 1530+ Upgraded Version NEW


TYPICAL INSTALLATION

 

 

N.B. The Antenna Interface is not used with the ALA 2000

 

CONCEPTUAL ILLUSTRATION OF THE HIGH ELECTRIC FIELD COMPARED TO
THE MAGNETIC FIELD CLOSE TO A LOCAL INTERFERENCE RADIATOR

N.B. The Loop nulls will also further reduce interference by up to 30dB.


An active whip or dipole antenna will also pick up high levels of interference.



 ALA 1530 Calibration Chart  .pdf file (fast download)

Wellbrook Communications



 







The
Reviews

Mike Richards reviews in RadioUser the Wellbrook ALA1530S+ Imperium

2013 RadioUser Review - Click Here

Reproduced with kind permission of the copyright owner PW Publishing Ltd and was originally published in their magazine RadioUser

Steve Nichols review in Radcom of the Wellbrook Communications ALA1530

2012 Radcom Review - Click Here

This article is copyright of the Radio Society of Great Britain (RSGB) and was originally published in their magazine RadCom. It is reproduced here with their kind permission. Please visit www.rsgb.org for more information about the RSGB.

Guy Atkins review of the Pixel Technologies RF PRO-1 and the Wellbrook Communications ALA1530

2011 Review - Click Here

Reproduced with Permission

Passport to World Band Radio

Review - Click Here

Copyright © 2008 International Broadcasting Services Ltd
Reproduced with permission



WRTH 2004

Click Here


PDF reproduced
by kind permission
of WRTH
World Radio TV Handbook


May 1999 - Paul Beam

Nov 2000 - John Wilson

Apr 2001 - John Wilson

Nov 2001 - John Wilson

K9AY - Oct 2002 - John Wilson

Radio Active

WRTH 1998
World Radio TV Handbook

CQ Magazine -
Japanese


Medium Wave Circle

 


Intermodulation - further explanation (should you want it!)





Related Links:

Willi Passman's Media Consulting

Werner Funkenhauser's Whamlog Pages

HamRad - Amateur Radio Operator's Guide to manufacturers,
dealers and organisations, as well as the home of the HamRad Trader.



Visit DXZone - Click Here



"Threat to Shortwave Broadcasting"


 

Specialists in Broadband Loop Technology!

Sales@Wellbrook.UK.com

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Designs and specifications are subject to change without notice

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