KL7UW

Lindenblad Satellite Antennas



Introduction
   The Lindenblad antenna is originally a design for aircraft tower communication but has characteristics
   that are very good for satellite operations.  The antennas were described in articles by Anthony
   Monteiro, AA2TX: "An EZ-Lindenblad Antenna for 2 Meters" and "A Parasitic Lindenblad Antenna for 70cm".
   In these papers Tony gives a very good review of the Lindenblad design.

   In brief the Lindenblad antenna produces an omni-directional circular polarized radiation pattern
   which is perfect for optimum reception of earth orbiting satellites.  Below I show my version of Tony's
   Lindenblad design.

   Where I differed on design is the use of 1-inch sched-40 pvc pipe.  I found it nested perfectly with aluminum
   sched-40 pipe, easing assembly.  I ran the four foot RG-58 coax inside the UHF driven dipole by drilling a
   small hole for the shield and insulated center conductor to pass thru the 4-way pvc hub (photo-1).  The PVC
   fit to the aluminum well without need for pvc cement.

   Antennas were tuned with a MFJ-269B analyzer.  The VHF Lindenblad was a shade low in frequency so a 8 pF
   silver-mica capacitor was used to shunt the coax connector bringing the frequency up.

   The UHF antenna is fitted with a mgf-1302 preamp so is only usable for receive (mode-VU).  Mode-UV or VU 
   are possible by use of the satellite antennas on tower-3.
   

Construction Details
  • Photo-1,2: Shows the white pvc four-way nipple dilled to accept the vertical dipole with coax run inside
  • Photo-3: Shows the two ferrite-beads at the lower end of the vertical dipole
  • Phtot-4,5: Shows the completed UHF "Parasitic" LIndenblad
  • Photo-6: Shows both VHF and UHF Lindenblad antennas on tower bracket
Installation on Tower-2
  • Lindenblad antennas mounted at 30-feet on Tower-2; HF, dual-6m, 70cm and dual 222-yagis above.
  • The small plastic box houses a coax relay and 432 GasFet preamp that is shared between satellite and the 432 yagi used for terrestrial contacts

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