Sunday, May 27, 2012

21MHz 7el OWA Yagi

A 7 element OWA Yagi for 21MHz with a 16.3mtr boom

Revised August 2010 v1.0
Premium commercial versions of this antenna at Innovantennas


I WILL MODEL THIS ANTENNA IN ANY TUBE SIZE OR TAPER SECHDULE FOR YOU, CONTACT ME VIA EMAIL

This is a high-gain, wideband OWA (Optimised Wideband Array) Yagi which covers the whole of the 15m band with an SWR of less than1.1:1. It has options with both UK/USA and European sized tube and has a 3 section taper.
This Antenna has been modelled using NEC4 and confirmed by FEKO. This is thousands of dollar of the very latest antenna design software available and the results are highly accurate. When loading into your software, you will see similar SWR but not the same. Please do not alter the model, build to these dimensions for the best results.
Contact me if you are unsure what correction (if any) you require for the element holders/stand-offs you will use or any other questions you may have.

Also read 'An intro to OWA Yagis' and 'Creating a Balun'

Antenna Layout and Construction:


 

Performance
11.89dBi @ 21.200MHz
23.86dB @ 21.20MHz
SWR: Below 1.1.1 from 21MHz to 21.450MHz

Construction details

Refer to the above drawing.

Antenna Dimensions for UK/USA sized tubing - European version below
Taper: Mid Section, 5/8 inch tube (total length 4.8m). Outer section 1/2 inch 2.4m long. End sections as per below schedule

                          Spacing                  End Section Length   (All below sizes in Metres)              
Reflector                0                              1.201                                         
DE1                      2.064                        1.133                                          
D1                        2.798                           .964                                         
D2                        4.881                           .948                                          
D3                        8.150                           .879                                         
D4                        12.452                        .820                                          
D5                        16.835                        .666                                          


Antenna Dimensions for European sized tubing
Taper: Mid Section, 16mm tube (total length 4.8m). Outer section 13mm tube 2.4m long. End sections as per below schedule

                         Spacing                      End Section Length  (All below sizes in Metres)         
Reflector                0                              1.199                                           
DE1                      2.064                         1.130                                            
D1                        2.798                          .962                                            
D2                        4.881                         .946                                            
D3                        8.150                         .877                                            
D4                      12.452                         .818                                            
D5                      16.835                         .664          

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