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DUBUS magazine and ARRL Antenna Book 2016 author, Justin Johnson G0KSC writes on the misconceptions of low noise Yagi antennas

I thought it was important for as many potential builders and Yagi users to see this as possible so with permission of DUBUS, the who article on the subject of low noise Yagis has been replublished here.

Within this article we will discuss one common misconception relating to Yagi antennas and what makes them ‘low noise’. One common use of the term low noise is in describing low temperature Yagis. Low temperature Yagis are beneficial for those looking toward weak signal applications such as EME and MS on upper VHF, UHF and up frequency ranges. However, Low noise Yagis and their associated benefits do not start there and I will attempt to explain and demonstrate how low noise Yagis are designed, used and benefited from on lower frequencies including some of the upper HF bands.

While I have presented these fact before, some have misinterpreted what I have referred to in respect of low noise Yagi designs and how they would benefit the user. One good example can be found HERE on the DK7ZB website. I have selected the individual statements from this page and provided a statement on why I believe these statements are not wholly accurate or perhaps not clearly enough written by Martin. Before moving on I need to reiterate that this is not necessarily Martin’s view, others have also interpreted incorrectly. However, Martin’s is publically displayed so a good place to start any correction statements.

‘’VE7BQH writes about 50-MHz-Yagis: Very low side lobes and F/R on this band produce no specific improvement in G/T based on pure sky noise and ground noise. Assuming reasonable side lobes, F/R and good VSWR bandwidth, Gain is the most critical parameter on 6M.

Very Low Side Lobes and F/R (Front to Rear) on this band produce no specific improvement in G/T

We need to pay attention to a part of the reference by Lionel, VE7BQH where he is quoted as saying this:

‘Assuming reasonable side-lobes, F/R (front to Rear) and good SWR bandwidth’

It is this part of the statement that could be easily missed or not noted as being important and is fundamental in ensuring best all-round performance on 50MHz. The part of the statement relating to G/T is true. However, it does need some explaining in order to provide the reasons this is miss-leading for the everyday-ham to be used as a part of a 50MHz antenna selection process. First of all, G/T or Gain over Temperature is a mean opinion score calculated by placing the antennas gain figure over the antennas temperature figure (or noise figure). The resulting G/T figures is a measurement used to determine an antennas ability to receive weak signals for purposes such as EME, MS and so on.

Pure Sky and ground noise are such at 50MHz that the temperature or overall G/T has no bearing on a Yagi’s performance from a reception perspective. However, the fact remains that most hams live in suburbia with noise levels of many S points (way above levels measured for G/T purposes) meaning any weak signals or potential DX that could be worked is generally covered by a high man-made noise floor. G/T will make no difference to these signals but a carefully modelled Yagi WILL reduce these ambient noise levels and in some cases by many S points. This will result in a station using such Yagi being able to hear and work weak stations they would not otherwise be able to hear.

What is not made clear in DK7ZB’s original statement is that as a part of the design process, optimisation for minimal side lobes and F/R (or what I like to call the ‘rear bubble’) plays a role in establishing a better G/T figure and/or a quieter Yagi but this is not the only factor. Additionally, these factors change band to band and what applies on 2m and 70cms (such as G/T and sky temperature) may have absolutely no bearing on receive performance on the 6m band.

As discussed above, G/T applies to upper VHF and up antennas but is only just coming into play on the 2m band (and is very important at 432Mhz and up). On these bands careful optimisation is again needed but the performance parameters and the way the design is addressed should be completely different on 2m and 70cms to the design parameters on 6m. Simply scaling and re-optimising will NOT yield the best results on each band, one-size does not fit all when looking at Yagis for VHF and UHF frequencies.

Let us now take a look at what DOES constitutes a low noise Yagi for bands such as 4m, 6m and upper HF.

Side lobe Suppression

As a Yagi increases in length, side-lobes appear either side of the main, desired lobe. These side-lobes are present in the Azimuth plane (looking down on the antenna from above, the way we mostly look at Yagi pattern) and the Elevation plane too (looking at the antenna from the side) and it is this elevation pattern which is the biggest issue and main reason for noise pick-up in urban environments and therefore needs to be addressed if the best user experience is to be seen.

Take a look at the plots below which compare a 9 element G0KSC LFA with a 9 element DK7ZB for 50Mhz.

                       

Fig 1 – The G0KSC LFA 9 (red) and DK7ZB 9 (blue) azimuth plots overlaid

                  

Fig2 – G0KSC LFA 9 (red) and DK7ZB 9 (blue) Elevation plots overlaid

Let us first take a look at fig1 which presents an over-lay of a G0KSC 9 element LFA and a DK7ZB 9 element split-dipole Yagi. Presented gain for both antennas is exactly the same at 14.48dBi. F/B on the DK7ZB is 39.17dB while on the G0KSC LFA 9, F/B (Front to Back Ratio) is just 29.57dB so the DK7ZB has the same gain, much better F/B and 1m shorter than the G0KSC LFA 9, the DK7ZB must be better right? We will come back to this point in just a moment. First, let us take a look at the elevation plot.

Fig2 shows the elevation plots for both antennas, once again overlaid with the field strength of the antenna and pattern from the side. From this plot we can see (or the trained eye can!) that the DK7ZB Yagi has been computer optimised but side-lobe suppression control has been applied to the azimuth plane only during the optimisation process. This is clear because the elevation plane pattern has ‘blown’, the elevation lobes are of significant size.

When optimising a Yagi, if side-lobe control is applied to the azimuth plane, lobes both up and down can extend uncontrollably as is the case on the DK7ZB Yagi elevation plot. If side-lobe control is applied to the elevation plane, the azimuth lobes are controlled at the same time, this ‘blown’ pattern effect does not happen when side-lobe control during the optimisation process is handled in the elevation plane, so what does this mean in the real world?

Imagine the horizontal centre-line in the middle of fig2 being ground-level and absolute center of the plot being your house/shack or tower. The blue and red lines represent the field strength in any respective direction from both the G0KSC LFA 9 and the DK7ZB 9. The largest up and down-facing lobes on the DK7ZB are only 13dB down on the most forward-facing and desired lobe. This means any signal coming towards the antennas frontal, main lobe at the same field strength as any signal from below the antenna at the same angle as the largest side-lobe will both be received just 2S points down on anything coming in from the front!

Some might say that the down-facing lobes are not there when the ground is present, they are reflected away. Again, this is not quite correct. While reflection does occur, the field strength remains in the positions of the free space Yagi along with any respective ‘gain’ these would produce when receiving.

The G0KSC LFA 9 is down at this same point 19dB, this equates to 3S points. If in a particular direction your noise floor is 3 S points on the DK7ZB antenna caused by a noise source coming in at that angle, on the G0KSC antenna noise will be 1S point or more lower (what if that rare DX was just over S2?).

Very deep nulls are present from this first side-lobe backwards on the G0KSC LFA 9 between the remaining heavily suppressed elevation lobes and it is this high-level suppression which drastically reduces noise pick-up from below the antenna and also the reason the outright F/B (front to back ratio) on the G0KSC antenna has been reduced. This reduction is a deliberate sacrifices (in F/B) to ensure maximum suppression from below the antenna occurs to help reduce noise from all sorts of day to day noise generators such as Plasma TV’s, DSL Modems, Alarm systems, WiFi routers and so on.

The same Scenario occurs within the azimuth plane too with noise being drastically reduced outside of the main lobe which results in any unwanted forward-facing noise either side of the desired lobe being greatly reduced.

Application examples and real-world experiences are always good when looking to cover and explain complex subjects such as this and I will use one provided from Peter G8BCG who installed an 8el LFA Yagi to compare with a M2 JHV antenna, the JHV having been designed using similar principles to the DK7ZB antenna.

Like others, Peter was a sceptic of the LFA and the in-built noise reduction properties of the antenna was said to have. Having the luxury of 2 x 60’ tilt and wide-up towers, Peter installed an LFA alongside is existing 6m Yagi to compare. Peter managed to work a station in Mongolia on 50MHz that he could hear on the G0KSC LFA but could not hear on the JHV. There was no noise from beneath either antenna as both were located in a field in the countryside. However, there were power lines in the distance and it proved to be power-line noise being received on the JHV that was the problem which was not present on the G0KSC LFA.

Upon experimentation, it was noted that it was not the fact that the G0KSC LFA did not pick up noise from the power-lines, to the contrary, when directly pointed at the power-lines, the noise was as present on the G0KSC LFA as it was on the JHV. However, at the angle at which both antennas needed to be for the Mongolian station to be received, the power-line noise was still present within side-lobes on the JHV which were not there (side-lobes) on the G0KSC LFA. At this point, pay special attention to Fig1 and the dramatic difference between the side-lobes/field strength on the two antennas. We are used to seeing ARRL plots when comparing antennas which while look nice, do not best represent how an antennas pattern really looks to emphasize the comparative differences between the lower-noise G0KSC LFA 9 and the DK7ZB 9, I have included a linear-overlay of the two antennas below in fig3

 

Additional methods of noise suppression and driven elements

Pattern is not the only method of reducing noise on a Yagi (although it can play a major role in reducing noise if optimisation is conducted in the right way). One commonly known issue is a result of static build-up within the driven element. Additionally, the broad-banded nature of split dipoles means that although directional properties disappear quickly when you move away from the design frequency of a Yagi, omni-directional receptive properties remain for many MHz either side of the desired band segment.

With an LFA (Loop Fed Array) loop or folded dipole fed Yagi (and as employed on my OWL (Optimised Wideband Low Impedance Yagis) the side of the loop opposite the feed point can be directly connected to ground. At the design frequency, this point of contact is one of zero current so is ‘not seen’ and has no detrimental impact on performance. It provides a DC ground to the driven element which allows both a static drain and a protection mechanism for the transceiver against natural occurrences such as lightning strikes. One very useful and additional noise reducing property is the band-pass filter effect this arrangement provides.

Unlike the split-dipole Yagi, the grounded loop feed arrangement becomes very high impedance quickly either side of the design frequency. This means you are less susceptible to receiving unwanted out-of-band noise/interference. Combined with a carefully considered computer optimisation exercise, A Yagi for modern-day environments and requirements can be produced which is resistive to modern-day man-made noise generators.

To this end, I will provide two examples of noise reduction comparisons, one on the 6m band, the other on 28MHz! Both independently produced and are 2 of many now place on Youtube and other Internet websites. This is on top of the many hundreds of confirmation Emails received by very happy users of low-noise Yagi antennas.

- 10m LFA comparison with TH6 by VK2GGC

- 6m comparison between 7el 50MHz WOS LFA and M2 7el JHV by VA3NCD - noise level change is significant. Lower gain LFA is louder on received signals due to reduced noise levels.

The next statement which needs clarifying is this one:

‘’Important: Yagis with a resistive input impedance of 50 Ohm must not have the best performance! For best balance of gain, pattern and bandwidth  the input impedance is always lower than 50 Ohm and you need a matching circuit for a feed of 50 Ohm. If you compare Yagis with 50-Ohm-direct feed these Yagis you mostly will see better patterns and higher gain with the 12,5- and 28-Ohm types!’’

What Martin refers to here is that split-dipole Yagis with a feed impedance lower than 50Ω are generally better performers all round if modelled correctly. This statement cannot be extended to generalise Yagis as a whole. Yagis using folded dipoles, LFA loops or bent elements (such as UA9TC, DG7YBN designs and others) are all Yagis which would have a lower impedance if more traditional driven and parasitic elements where used but have been cleverly adapted in order that a 50Ω impedance is seen without having to add third-party matching devices after the design. In so doing, all potential losses and structure impacts on pattern are seen and predicted at the software model stage, there are no surprises once built!

However small this loss may or may not be, there is no method of transforming anything known to science that is 100% efficient and by modelling a ‘self-matched’ Yagi with all aspects considered, a much closer representation of the end result can be achieved and summarised.

As a foot note, some of these steps forward in self-matching Yagis have led to more than just presentation of a 50Ω feed impedance as in some instances, marked differences have been seen in pattern too. As with certain longer LFA models, the re-shaping of certain elements leads to a much tighter, cleaner and quieter pattern than without. Some good examples can be found on the DG7YBN website where the GTV antennas employ bent driven elements to transform a lower impedance Yagi to one of 50Ω.

YU7EF Bent Element Example

In order to demonstrate the enhancements that can be seen from the addition of bent elements, below are two Azimuth plots for the YU7EF EF0213M6. The first marked ‘std’ is the default YU7EF Yagi using all straight elements. The second is the same antenna with no other adjustments other than a UA9TC single reflector replaces the straight one in the original antenna. Note that no other adjustments have been made at all yet the suppression to the rear of the Yagi has improved dramatically over the standard antenna (in the order of 10dB F/B) and a small improvement in gain is also seen.

As no adjustment of any other part of the antenna has been made, and due to the fact that the UA9TC reflector increases feed point impedance, the SWR curve of this antenna remains flat but now at around 1.5:1 across the band from 144MHz to 145MHz. Optimisation of the antenna (including reduction of the feed point impedance to 50Ω should result in further improvements to the antennas performance including higher levels suppression and gain as a result of the impedance drop.

Standard YU7EF above

YU7EF fitted with UA9TC reflector

To demonstrate the results that can be obtained when using a computer optimisation program along with the UA9TC reflector, I present below a 14 element Yagi having been computer optimised with the UA9TC reflector in place. Control has been given to the computer to adjust the width of the reflector and the length of the forward-facing sections too which can see seen in the element layout illustration below.

 

G0KSC designed UA9TC style Yagi

SWR Plots for the G0KSC Designed UA9TC style Yagi

Substantial increases in F/R have been seen as a result of optimisation with this reflector in addition to a very flat and exceptionally wide SWR being achieved too. It is not just the azimuth plot which shows excellent suppression, the elevation plot is as impressive if not more so. While the first (and only) forward-facing lobe in both plots may appear to be pronounced, it is in fact a result of the rear-bubble being so drastically reduced over what would be considered usual.

 

Elevation plot

Element layout and reflector shape of the UA9TC style reflector Yagi

Above: Elevation plot of the 14 element G0KSC ‘TC’ Yagi using the UA9TC style reflector. Second image, the same antenna element layout showing the reflector, its shape and position.

Conclusion

A low noise Yagi is not something limited to those users of upper VHF and UHF bands and benefits can clearly be seen within noisy environments when a Yagi is optimised in a certain way. Benefits associated with Elevation plane optimisation can be seen at HF frequencies as well as VHF frequencies as a result of the improved signal to noise characteristics of a Yagi optimised in the way we have discussed. Certainly, gain is not the most important parameter in modern-day, suburban environments. In these cases, Signal to Noise ratio remains the most important aspect within a Yagi in these environments, at least it is if we want to hear as well as be heard!

New and exciting techniques to model and optimise Yagis for low noise and super-clean patterns include the ability to optimise without having to use any form of matching methods outside of those already optimised as a part of the antenna itself and as time goes on and more experimenters and modellers adopt these methods, I am sure further enhancements and development will result.

In a future article to appear in DUBUS I will be drilling down into the UA9TC style reflector and other new ‘bent element’ methods of Yagi enhancement and how the type of arrangement chosen, may influence the point at which ‘optimum’ (boom length) balanced performance can be achieved.

Credits:

UA9TC, DK7ZB, YU7EF, DG7YBN

 

Premium commercial versions of G0KSC antennas ONLY at Innovantennas

An Introduction to the Low Noise Yagis

Optimising for Signal to Noise Ratio (SNR)

Updated 26th December 2015 -

NOTES ON MATCHING YAGIS:

A long time has passed since we have to accept the negative aspects of matching Yagi antennas. With modern software, knowledge and optimisation techniques, there is no reason for a Yagi to have any form or matching device. If designed correctly, the Yagi will present an excellent SWR curve over a given operating range when directly fed. There is no reason for any low impedance Yagi to provide better performance characteristics than a 50Ohm type with or without the negative impacts and unmeasured losses matching devices induce.

TRANSFORMING IMPEDANCE:

It is also important to note that there is no method of transforming anything, including impedance which is 100% efficient. This can be seen by the fact that any Yagi with a matching device has an input power limit, why? Because the matching devices gets hot. What makes it get hot to the point of destruction with just a few hundred Watts? The fact that so many of those valuable Watts are being lost as heat and not radiated from the antenna. So why are antenna matching devices so commonly excepted? One reason is highlighted in the next section, Software Desgin Limitations.

SOFTWARE DESIGN LIMITATIONS:

Software packages commonly used by 'amateur' antenna designers are free or cost a few hundred pounds/dollars. While on very simple Yagis - those with straight, un-tapered elements and no complex element arrangements - accuracy can be achieved, once any form of complexity is added to these modelling engines or matching devices are added to the software model, huge inaccuracies occur. This is one good reason that modellers using EZNEC +, MMANA, 4nec2 (without the NEC4.2 engine) do not model, build or recommend non-conventional Yagi fed arrangements. Yes, there ARE hidden agendas!

Below is a good example as to why 'amateur' antenna modellers cannot provide accurate designs for modern-day direct fed 50Ohm Yagis. The same antenna is modelled for SWR using EZNEC version 6. However, the first is using EZNEC+ version 6 (EZNEC Pro/4 with the NEC2 engine enabled), the second using EZNEC Pro/4 version 6. What is the diference? EZNEC + version 6 costs $149.00 and includes the NEC2 calculation engine. This is an electromagnetic design engine which predicts the performance in software of how an antenna might perform in the real World. The NEC2 engine has had no development ofr more than 25 years and is now free for anyone to use and completely open. TYhe disadvantages is more thna 25 years worth of inaccuracies and errors will exist for anything other than the most simple of antennas.

EZNEC Pro/4 version 6 is the professional version of the EZNEC program which costs $675.00 for the base product. The most important aspect of this version of EZNEC is accuracy. The product uses the current continually developed version of NEC, NEC 4.2 which has a license fee of $500.00 for non-commerical use, $1500.00 for commerical purposes. Any bugs found, are fixed. Any inaccuracies reported, are investigated and fixed. Therefore, while the initial investment will be $1175.00 best case scenario, accurancy is assured.

7el 50MHz LFA using EZNEC Pro/4 version 6 with NEC4.2 engine

7el 50MHz LFA using EZNEC Pro/4 version 6 with NEC2 engine enabled to replicate EZNEC + version 6

So perhaps this is another reason why matching devices are still commonly used within Yagi antennas, even with element taper correction algorithms in place, inaccuracies still exist, the antenna when built is still not as the model would suggest in terms of SWR and ultimately presented (software) performance parameters. An easy route to making the antenna look correct in the real world is to add a matching device. This can be adjusted to make the SWR look good wherever you want it to and mask the fact the antenna model has not be replicated. you could even construct the Yagi with elements in the wrong position and in some case, still adjust a matching device to show a good SWR. what on Earth would the antenna be doing performance wise? Makes you think doesn't it?

APPROPRIATE DESIGN PARAMETERS FOR VHF/UHF YAGIS:

Another failure of the 'amateur' antenna modeller that spilled into the commercial World more than 20 years ago is the inappropriate optimisation of VHF/UHF antennas for highest possible gain. This has produced an environment that is not ideal yet VHF and UHF operators have come to accept as being normal. This is one where if using any form of amplified power, you will always be in a position where you can be heard by more stations than you can hear (generally weaker, smaller ones). So what is the issue with optimising for highest possible gain?

Let us take a look at the entire receiver chain form the radio to the antenna. The Antennas is the very front-end of the receiver and is collecting all signals which will be processed by the receiver itself. When a receiver is being setup and tuned, each section of the receiver is not tuned for maximum gain, it is tuned for minimum noise, why? Receiver performance is all about signal to noise ratio - the delta between the desired signal and the noise floor - this is known as the signal to noise ratio. If the receiver is tuned for absolute maximum gain, the difference between the wanted signal and noise floor reduces and therefore, the signal to noise ratio has reduced meaning the ability of the receiver to be able to hear weak signals has decreased too.

So if we tune every aspect of the receiver for minimum noise, why optimise the antenna - the front-end of the receiver - for maximum gain? It goes against the setup parameters of every other part of the receiver chain and is therefore counterproductive. Make no mistake, there is no difference between what happens elsewhere in the receiver chain and that of the Yagi, optimising for every last ounce of gain reduces the ability of the Yagi to receive weak signals.

MISREPRESENTATION OF PERFORMANCE MEASUREMENTS SUCH AS G/T:

Have you ever heard the saying 'A little knowledge is a dangerous thing'? This applies in so many areas of life including antenna modelling. A good example is when Yagi design parameters for one band are confused or integrated into another. A Yagi of a given size which is ideally optimised for one band, may not be an optimal Yagi if scaled for another band and there are many reasons for this but it is often one that is cloudy and the really associated benefits or reasons they need to be different is not widely known.

DK7ZB presents a case on his 50MHz Yagi page that Yagis with reduced side lobes are not needed for this band with the reason given being that G/T - Gain over Temperature a mean opinion score for the measurement VHF Yagis ability to receive weak signals - makes no difference to the antennas performance on the bases that the reduction of side lobes makes no significant improvement to the G/T of Yagis on 50MHz.

The first point of note requires an understanding of G/T and what the temperature measurement is that is described in this passage by DK7ZB. Temperature refers to Sky Temperature which is measured in degrees Kelvin. At upper VHF frequencies and UHF frequencies and where the antenna/station is in very quiet locations away from city environments, background noise levels are extremely low. In these unusual and rare conditions, background noise level changes can be heard when Yagis are in close proximately to or pointing ate ground, or sky based noise producers such as the Moon or Sun.

The G/T measurement provides an indication as to the level of noise a Yagi will pick-up from warm earth or sky based noise generators when the Yagi is pointed away from these subjects. This information is very useful for ham wanting to use very weak signal modes such as Earth Moon Earth (EME), meteor scatter and other such modes. However, the issue here is the exceptionally low levels of noise generated by 'warm earth' are irrelevant at 50MHz as Sun noise is significantly higher than warm Earth on this band. Therefore, quoting G/T performance at 50MHz has no bearing at all.

For most of us however, there are much higher noise sources in urban or city environments that will impede our ability to enjoy the bands we love. 50MHz is one which suffers with a lot of high-level man-made noise and significantly reducing side lobes in all directions (specifically straight up and down) by optimising the Yagi for minimal noise, not maximum gain - optimising for signal to noise ratio - drastically improve the user experience by increasing the stations ability to hear weak signals.

 

 

The image above shows DK7ZB designed Yagi (blue) overlaid with a G0KSC Low Noise Yagi (red) of a similar boom length, in the elevation plane. Elevation meaning the lobes on the '0dB' line which are lobes looking directly upward, and straight down below the antenna (maybe your shack, your house or neighbours house are in view of these lobes?). Optimising for minimum noise has drastically reduced side lobes in these directions by between 1 and 2 S points in some cases. Can you imagine the impact on your user experience if in some directions you have a noise floor of S3 and this could be reduced to S1? This is the reality of giving up a few tenths of a dB of forward gain - the ability to hear more as well as be heard!

Not a G/T measurement in sight for this reality check. So how real is this? Take a real world example. This ham in Canada had the luxury of being able to install a new 50MHz 7 element LFA along side his original antenna, a popular 7 element antenna designed by a well-known American brand which has been designed using the 'gain, gain, gain' concept. Note that no just is the noise floor a lot lower on the LFA Yagi, this received signals are comparable which means they are far better received on the LFA. In some instances, the signals are beaering heard on the traditional style Yagi but Q5 on the LFA.

So is it just 6m that the Yagi optimised for Signal to Noise Ratio works best on? No, it will show improvements on any band where you are in a high-noise location, city lots, urban locations infact anywhere other than a shack that is in the middle of no where! Take this next example, a 28MHz LFA Yagi installed at a relatively quiet club station. Note again the background noise difference and the delta between the signal and noise as the antennas are switched.

What more proof? There are many noise comparasion examples on YouTube, take a good look around. Also, ask LFA users (not those that don't have LFAs) about their experiences and the difference between what they have now and what they have used in the past.

''MY ANTENNAS ARE AS GOOD AS AN LFA SEE THE PLOTS'':

The above statement is made by others often, I have seen this on many a website. You are sold on the low noise benefits of G0KSC antennas optimised for SNR, so are many amateur and ham antenna designers are too. However, having promoted their more traditional style Yagis for many years means it is difficult to pull away from and now recomend something else, credibility and integrity are at stake. Additionally and as we have discussed, they do not have the means to accuratley model such antennas in software anyway. As a result, they stick to their traditional, simple designs and provide cleverly presented comparisons. Could potential G0KSC Yagi users to go another route if an antenna appears to be the same or better? It is possible, ultimately, the decision is yours but ensure you compafre apples with apples. If this pattern is the same at one frequency, is the bandwith the same? How about the side lobes either side of the compared frequency, still good? Check VERY carefully because ultimately, you could be sold out of every-day usable performance.

There is far more to a low noise Yagi than spot-frequency side lobe reduction, so many that it would need a chapter in a book such as The ARRL Antenna Book 2016 (which I am a contributing author of) to explain it all. Antenna bandwidth is important too, as is the optimisation of the Yagi in the Elevation plane rather than the Azimuth plane in order to enhance wet-weather stability. It is far easier to obtain a low noise looking Yagi with a very narrow bandwidth than it is to produce a very wide band antenna like the G0KSC LFA, OWL, OP-DES (etc.) that remains stable pattern-wise over a wide bandwidth. The narrow-band Yagi looks good on paper and at one frequency but how is it at either side of the band? What does it perform like when wet or covered in snow?

Make sure that low noise antenna you see is not all smoke and mirrors. If there is any doubt, stick with the G0KSC Yagi!

Contact me with any questions you may have

Justin G0KSC

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