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50/70Mhz 4el Quad

G0KSC SC6-4-4DQ 4el 50Mhz/70Mhz Dual band OWA Quad Antenna with a 2.7 Metre Length Boom

About this Antenna

This is a dual band Quad for both 50Mhz and 70Mhz which has just 4 sets of spreaders which each hold a quad element for each band. There are two feed points too, one for each band.The spreaders have been spaced in order to bias the best front to back upon the 50Mhz band and more gain bias upon the 70Mhz band. 

As with most of my antennas, both driven elements provide a 50 Ohm impedance to direct coax connection with no matching unit (or 1/4 wave lengths of coax of another impedance).

This is a great performing antenna for such a short boom length. Very light weight too. Enjoy!

SWR and bandwidth

As we are using a common set of spreaders the SWR can not be as flat as with a single band 50 Ohm quad.

Sizing and spacing are as follows:

Dimensions in Metres

Element spacing:

  • Ref      =     0
  • Driven  =    1.198
  • D1       =    1.758
  • D2      =     2.752

Element sizes per element half:

  • Ref 6     =      6.288
  • Ref 4     =      4.492
  • Driven 6 =      6.096
  • Driven 4 =      4.412
  • D1-6      =       5.552
  • D1-4      =      4.332
  • D2-6      =      6.016
  • D2-4      =      4.232 

Performance figures @ 50.250Mhz:

  • Froward Gain: 9.64dBi free space
  • Front to Back: 21.08dB
  • Radiation angle at 10 Metres above ground: 10 degrees

Performance figures @ 70.250Mhz:

  • Froward Gain: 10.41dBi free space
  • Front to Back: 12.04dB
  • Radiation angle at 10 Metres above ground: 5 degrees

 

Element diameter:

This model is created with 2mm thick copper wire

 

For construction information see 'G0KSC insulators' and the UKSMG article from the main menu on the home page. 

 

 

 

 

 

 

 

 

 

 

 

 
 
 
 

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