9el 144-145MHz Yagi OWL-Ultra Super low noise Yagi

Manufacturer InnovAntennas

9el OWL Ultra - 144-145MHz for super low noise Yagi for weak signal operation
Sales price £269.95
gross price
Sales price without tax £224.96
Sales price without tax£224.96
Tax amount £44.99
Total Tax: £44.99
Boom Diameter
Boom Diameter


A 9 element OWL-Ultra (5.1m long) Super low noise, light weight Yagi 144-145MHz Optimised for weak signal (EME) operation - New 2020 Model!

Still the WORLD's BEST 9el 144Mhz Yagi in terms of G/T, beign the first 9el to dip below 6dB (-5.90dB G/T) on the VE7BQH list

X-pol available upon request & full EME system prices available upon request - This email address is being protected from spambots. You need JavaScript enabled to view it.


Modelled and finalised with Ansys HFSS 2020 R2 fully meshed antenna modelling software. All aspects of the antenna are measured and modelled including boom, insulators and coax cable ANSYS.

OWL Ultra

A 9el 144MHz OWL Ultra installed and ready for action

A note on accuracy

In order for a low noise VHF or UHF Yagi modelled in software to stay low noise when built, the whole antenna needs to be modelled, optimised and finalised as it will be built. Elements, boom, insulators, feedpoint and even coax cable being connected to the model. This way no 'correction' needs to be added, the exact element lengths are given within the software which in our case is the World's leader and most expensive simulation package available today Ansys HFSS.

a 'Fixed' length correction such as forumlas given by K1FO and DL6WU, will NOT replicate a wires only model to real world antenna. Any such correction would be percentage based with a lower percentage being needed for first and last elements.

boom with coax

A 70cms LFA Yagi as presented within Ansys HFSS showing all aspects of the antenna being factored into the model

rear antenna balun

A 70cms Ultra Yagi from the front in Ansys HFSS with ferrite core balun attached. All aspects of the antenna are factored into the design

Fully customisable design - what you want, we will make

If you require a larger diameter boom, rear mount, X-pol, a variation in frequency coverage or other variation, contact This email address is being protected from spambots. You need JavaScript enabled to view it. detailing your requirement for a custom quote.

The G0KSC OWL Ultra is another fantastic design by G0KSC. A low impedance Yagi provides excellent performance. However, traditionally, low impedance has meant narrow bandwidth.

G0KSC developed the OWL (Optimised Wideband Low impedance Yagi) with a folded dipole driven element which this has increased the feed point from 12.5Ω impedance to 50Ω. This along with careful, long duration computer optimisation hasresulted in a much wider bandwidth than previously seen in native low impedance Yagis.

THE Low Noise Yagi dubbed the 'Urban Yagi'

The super low noise characteristics of the OWL Ultra mean you can HEAR as well as be heard in today's modern and very noisy city environments. If you want the very best option for minimal nosie pick-up in Urban and city locations, the OWL Ultra is for you.

Best in Class performance in terms of G/T?

Antennas finalised in fully 3Dmeshed packages with thru-boom elements are not easily reverse engineered into EZNEC and the VE7BQH table required NEC based models in order to be listed.

Important Note: 

Convergence correction calculator with bent elements and folded dipoles are in use. Additionally, convergence correction should also be applied when hairpin and T-matching systems are in place in the model. If this is note done, artificially high-performance results may occur. Additionally, if matching devices are not applied to the model, associated matching loss will not be considered in the model either and again, artificially high performance figures may result.


Excellent wet weather performance

The OWL Ultra is usable in all weathers. Unlike some antennas that shift frequency and become unusable when wet, the OWL Ultra remains perfectly usable.

Latest and best G0KSC designs only available through InnovAntennas

The OWL-Ultra is the latest, 3rd generation OWL and provides G/T performance not seen at this boom length previously (VE7BQH independant comparison list). The latest G0KSC designs are ONLY available through InnovAntennas. This antenna is the best every 9el 144MHz Yagi on the list @ -5.90dB G/T

Elevation lobe suppression is key

One of the reasons the OWL Ultra performance is better than other Yagis of the same size is the special attention paid to elevation lobes during the optimisation process. Whether you believe you live in a quiet location or not, elevation lobes will ensure your received noise floor is higher than it would otherwise be if they were greatly suppressed. Even if you have a shack in the middle of open countryside, if your shack is directly below the antenna or in view of the antenna in certain directions, noise from everything in the shack (from  computers, modems, LED lamps, alarms WiFi adapters etc.) will increas your noise floor. The highly suppressed elevation lobes of the OWL Ultra will ensure your noise floor is as low as possible.

All elements and dipole perfectly in-line

All of the thru-boom OWL and LFA Yagis, all elements, including the feed point are perfectly in-line and as there are no 'lossy' matching devices standing off of the driven element to distort pattern pattern remians perfectly clean and this means the low noise properties of the antenna remain.

Grounded driven element

There are many associated benefits of having the driven element electrically connected to the boom and therefore grounded. This is much more difficult to achieve in a split dipole Yagi and in addition, not possible to model within NEC based simulation tools. The folded dipole or LFA loop is grounded to the boom opposite the feed point. This is a point of zero current (everything radiated by this point) and therefore, is not seen at the design frequency. However, the dipole will become very high impedance either side of the design frequency very quickly and this, a Band Pass Filter property is added to the antenna 'for free'. Another associated benefit is having the driven element grounded means static cannot build up in the folded dipole as it could with a non-grounded driven element system and potentially damage the receiver as with the grounded system, static can drain harmlessly away.

Mechanical design

The new OWL Ultra is designed in a light weight and very strong package with this particular model using a 1" square boom with through boom (insulated) 1/4" solid rod elements. The driven loop is adjustable in order to ensure absolute minimum return loss figures can be seen and is made from 1/2" tube with 3/8" diameter loop ends which trombone to provide the finalisation tuning ability. The folded dipole is through the boom as are the parasitic elements although the section of loop opposite the feed point is grounded to help reduce noise and to help protect the receiver front-end against static. Grounding the loop in this way also provides a band pass filter characteristic. The feed impedance goes very high quickly once moving away from the 2m ham band and this results in a filter property being added to the antenna for out-of-band signals, received or transmitted.

G0KSC variable element correction applied

SWR characteristics are unparalleled as a result of the applying of G0KSC variable, percentage based correction to all through boom elements. Fixed length element correction does not match software models precisely. The correct method is to apply a % to the elements which vary greatly between the first (reflector) and last (final director) elements. However, an added complication is that the first and last few elements at either end of the boom, require less correction than those centrally mounted on the boom. Don't woory, all these correction issues are taken care of by G0KSC during the design and testing process.

Other benefits include:

  • Marine grade stainless steel fittings
  • Super-light but rigid construction
  • Mill finished boom and elements for highest levels of accuracy
  • Unparralleled after-sales support and assistance when needed


For more information Email Here


Gain: 14.6dBi @ 144.3MHz (Ansys HFSS 2020 R2 verified)

F/B: 33.25dB @ 144.3MHz

Peak Gain: 14.23dBi

Gain 10m above ground: 22.83dBi

Peak F/B: 37.43dB

Power Rating: 5kw

SWR: Below 1.2:1 from 143MHz to 145.2MHz

Boom Length: 5.15m

Weight: 3.5kg/7.7lbs

Safe Wind Speed: 160Kph/100Mph

Turning Radius: 2.74m/9ft

Vertical Stacking: 2.7m for minimum under-lobes

Custom Stack: Provide you requirements, location, height above ground and intended use and we will custom-produce the ideal stack

G/T: -5.90dB - Wolrd's best 9el 144MHz Yagi as December 2020 - current (January 2022)


9el plot

Elevation Plot of the 9el OWL Ultra presented within Ansys HFSS


SWR Plot of the 9el OWL as presented in Ansys HFSS


Measured SWR on a built 9el OWL Ultra by G8FJG

 3D model

The fully 3D model as presented in Ansys HFSS - all factors of the antenna are represented in the model from the boom with insulated elements passing through it, insulators set in the boom and grounded driven loop. NO correction needs to be added to any of the elements, the antenna element sizes are finalised in the model and the built antenna respresents the model perfectly.


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