An introduction to the LFA Yagi

The LFA (Loop Fed Array) Low-Noise Yagi is very different from the traditional dipole fed Yagi in many ways with its primary benefit being unwanted noise rejection. The LFA has a rectangular shaped, full wave loop driven element that is laid flat on the boom between and in-line with the parasitic elements .  Then there is the way in which the loop functions. The smaller end sections which run parallel to the boom, are engineered to be 180 degrees out-of-phase with each other. This provides the same effect as is seen within ladder-line feeder; each side cancels the other out and therefore, minimum radiation occurs.  In practice this translates to highly suppressed side lobes and side-on signal rejection. This feature also plays a role in reducing F/B (Front to Back ratio), F/R (Front to Rear ratio) and broad-banding of the antenna too. It is these attributes which help give the LFA class-leading all-round performance at almost any boom length and for any given band.

Below are a list of Key Benefits the LFA Yagi provides:

• Full-Wave Closed Loop Feed System
  • The closed loop system helps reduce the reception of man-made noise and static
• 50Ω Direct Feed - No Matching Loss
  • The LFA Yagi has been carefully Optimised in order to ensure a 50Ω feed-point. This ensures no matching loss and minimal resistive (Ohmic) loss
• High F/B ratio
  • Another attribute of the LFA Yagi is the exceptional Front to Back ratio it has for a direct-feed, 50Ω Yagi. Get rid of unwanted signals from behind your antenna!
• Super Wide Bandwidth
  • Another unique characteristic of the LFA Yagi is the excellent bandwidth the antenna possesses. This ensures very large portions of a given band can be used with little return loss
• Constant Impedance & 'All-Weather' Stability
  • A very rare feature is the ability for an antenna to provide the level of performance of the LFA and be stable in all weathers. This is provided by the LFAs constant impedance
• Wide-band Performance Maintenance & Stability
  • Unique to the LFA is Wide-band Performance Maintenance. Many antennas have their best F/B at one end of the band and best gain figure at the other end. The LFA extends its performance across a very wide pass-band

• Class-Leading Sky Temperature and G/T figures
  • For Earth-Moon-Earth and other weak signal modes, no other antenna comes close to the LFA. Search for the VE7BQH G/T Table and compare the LFA with everything else. Nothing comes close
• Highly Suppressed 'Rear Bubble' for All-Round noise reduction
  • With any side lobes being highly suppressed in all areas other than that of the direction in which the antenna is facing, your receiver only 'hears' what you want it to
• The Most Important Part of your Receiver has to be The Best
  • Your antenna is a part of your receiver and arguably the most important part of your station. You have spent thousands on radio equipment, make sure you don't short-change your set-up by choosing anything else other than the InnovAntennas LFA Yagi
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The LFA helps you hear the stations that can hear you. For many stations with power, being heard but not hearing is commonplace. With the installation of the LFA at your station things really can be different! Not only will you have no amplifier SWR issues within any part of the band you wish to work* you can work the DX knowing that much more of what can hear you, can also be heard at your station.

Within weak signal environments such as MS (Meteor Scatter) or EME (Earth Moon Earth) LNAs (Low Noise Amplifiers) are fitted to ensure minimum unwanted noise pick-up is seen and as much of the desired signal is seen and amplified. However, until now the most important part of the receiver (the antenna) has been missed. Installing the LFA will ensure your LNA has the best platform from which to amplify your weak signals. Take a look at just how a long 144MHz EME antenna looks.

Incredible levels of F/B and F/R are seen from this antenna which shows never-seen-before levels of Sky Temperature and G/T on 144MHz. However, it is above 144MHz that the LFA really comes into its own. If comparisons were made between the LFA traditional 432MHz Yagis, huge differences would be seen.  In recent comparison tests, an 18 element LFA Yagi provided better G/T (ability for an antenna to receive signals) figures than  much larger traditional dipole/folded dipole fed Yagis of up to 24 elements in length! This is typical of the LFA on these bands and is one of the reasons the LFA will become known as one of the big steps forward in the development of the Yagi.

Many hams and commercial entities are already experiencing how the LFA can transform what they are able to achieve in terms of performance and many more will continue to do so as time goes by. Do you want to be a follower or a leader? Make room on your tower for an LFA on your favourite band and you too can be surprising others with just how well your station can perform!

* Some LFAs are designed to cover only a given section of a given band not the whole allocation.

 There is a Patent Pending on the LFA Yagi - all enquiries to InnovAntennas Limited