A 13el 28 Ohm 144MHz Optimised Wideband Low impedance (OWL) Yagi

Premium commercial versions of this antenna at Innovantennas

The OWL by G0KSC provides the benefits of both OWA (Optimised wideband Array) 50 Ohm antennas with those of traditional low impedance antennas. More information on the OWL can be found in the CONSTRUCTION menu.

Do not look at the gain figure of this antenna and compare with other 13 element 144MHz Yagis. Compare the gain, F/B and bandwidth together against other antennas of a similar boom length. With 16.44dBi (10mm element version) and a boom less than 8.3M long, this antenna will be a winner for field days and the rural Ham radio operator. Class leading G/T figures too!

PLEASE NOTE:

• Visit 'Making the OWL Match' for more information on the recommended matching methods
• Please add 2mm to each element to allow for insulator correction if using insulators similar to G0KSC. If through boom/insulator/element bolts are used, add 3mm

Performance UK/USA Version

Forward Gain:                           16.43dBi at 144.300MHz

Front to Back Ratio:              26.61dBi at 144.300MHz

Peak Gain:                                 16.47dBi

Peak F/B:                                26.81dB

Bandwidth:                               1.9MHz below 1.1:1

Build Dimensions for UK/USA Version

Element           Spacing in metres Half element Length in metres    Element Notes

Reflector               0                                   .512                                 3/8 inch tube

DE                       .202                               .4955                               1/2 inch tube

D1                       .383                               .4775                                3/8 inch tube

D2                       .845                               .465                                 3/8 inch tube

D3                     1.484                               .4555                                3/8 inch tube

D4                     2.236                               .4475                                3/8 inch tube

D5                     3.045                               .441                                  3/8 inch tube

D6                     3.901                               .4355                                3/8 inch tube

D7                     4.779                               .430                                  3/8 inch tube

D8                     5.672                               .4255                                3/8 inch tube

D9                     6.583                               .421                                  3/8 inch tube

D10                   7.508                              .4205                                  3/8 inch tube

D11                   8.256                              .433                                    3/8 inch tube

Build Dimensions for European Version

Element           Spacing in metres Half element Length in metres     Element Notes

Reflector               0                                   .5115            10mm tube

DE                       .202                               .496              12mm tube

D1                      .381 .477                                            10mm tube

D2                       .845                               .4645            10mm tube

D3                     1.484                               .455              10mm tube

D4                     2.236                               .447              10mm tube

D5                     3.045                               .4405             10mm tube

D6                     3.901                               .435               10mm tube

D7                     4.779                               .4295             10mm tube

D8                     5.672                               .425               10mm tube

D9                     6.583                               .4205              10mm tube

D10                   7.508                              .420                 10mm tube

D11                   8.256                              .4325                10mm tube

Antenna Plots

Fantastic Azimuth plot of this 13el 144MHz OWL Yagi

The Elevation plot is really clean too. A quiet antenna compared with most!

This SWR plot is taken with the Coaxial stub embedded within the EZNEC model Ever seen a 28 Ohm antenna like this one before? Watch how many now appear on the Internet but remember where you saw them first!

The G0KSC OWL element layout. Note the close spacing of the first 3 elements which give the OWL its extra gain and wide bandwidth.

As always, or if you have difficulty at all, please Email me!

Justin G0KSC

A Low-Noise 'Urban' 4 element LFA Yagi for 144-145.5MHz

Revised February 2010 V1.0

Premium commercial versions of this antenna at Innovantennas

The LFA design has a patent pending and all G0KSC designs are copyright. Any ham can build for their own use or those of a friend. Where profit or commerical gain exists, express permission of G0KSC must be sought.

If you suffer with noise from living in the city, this is another low-noise antenna from G0KSC

This one is really nice and compact, has good bandwdith (over 1MHz 1.1:1) and yet has maintained an excellent pattern at the same time with more than 10dBi.

PLEASE NOTE:

• This antenna WILL NOT show the true SWR in any antenna modelling package unless you are using one which uses the latest NEC4 calculation engine. Do not confuse your version of EZNEC with nec version. EZNEC uses nec2 by default.
• There are two sets of measurements listed below. One uses imperial sizes, the other uses metirc sizes. Ensure you use the correct one for the material you have
• 'within one or two millimetres' Will not do! take the time to ensure you get the spacing ant element lengths as close as you possibly can to the measurements below to ensure good, solid performance
• Please read the 'how to make the LFA Loop' page here

2 x 9 element versions of this antenna at the RSGB VHF Field day 2009

Note: performance figures centred on 144.300MHz the centre SSB frequency

Performance

Forward Gain:                   10.06dBi at 144.300MHz

Front to Back Ratio:          20.06dBi at 144.300MHz

Bandwidth:                                  1MHZ below 1.1:1

Please read the 'how to make the LFA Loop' page here

Azimuth Plot of this wideband 4el 144MHz LFA

Elevation Plot

SWR Plot from 144MHz to 145MHz

Antenna Layout

Build Dimensions for UK/USA/European version Version

Element                             Spacing in metres Half element Length in metres            Element Notes

Reflector                                0                                                           .5155 3/8 Inch -  .5145 10mm  Tube

DE1                                       .136                                                     .426 Either  1/2 inch or 12mm Tube same size for both

DE2                                       .324                                                      .426 Either   1/2 inch or 12mm Tube same size for both

D1                                         .657                                                      .4625 3/8 inch - .4615 10mm  Tube

D2                                        1.224                                                     .4365 3/8 inch - .4355 10mm  Tube

Notes:

DE1 and DE2 are joined at the ends by either 10mm or 3/8inch tube. Feed point is the centre of DE1

Please read the 'how to make the LFA Loop' page here

As always, any questions please ask!

Justin G0KSC