VOR/GS diplexer on a shoestring

[H.Zwakenberg]

Hi Group,

 

for my IBIS project I purchased a KN53 VOR/LOC/GS receiver. I didn't fancy installing two antennae (VOR/GS), so I need a device called a "diplexer".

I didn't like the idea of $helling out some $100+ for a diplexer either, as this would be as expensive as an antenna would have been.

 

That's why I rolled my own VOR/GS diplexer design. You can download the documentation on http://ibis.experimentals.de Just go to the download section and from there select 'documents' from the submenu. Scroll down the table of downloads and you'll find there.

 

Enjoy!

 

Hans

[dpaton]

6th order filters...very nice. I assume it's impedance-corrected too?

[H.Zwakenberg]

yes, 6-th order Chebyshev filters are nice...

 

Input impedance is 50 Ohms, on both outputs the impedance is slightly higher (only 10% - caused by having to stick to standard value components), which causes only a minimal mismatch.

 

One more note: this diplexer is for two receivers only, DON'T think about putting a transmitter on one end.... Today I'm going to put a rev. 1.1 on my site with warnings to that extent.

 

Hans

[argoldman]

I gotta dumb question:

 

What about just making a glide slope (foil) antenna nested on the bottom of the canard. They are quite small. Any splitter is going to decrease the signal to your receiver which means less range.

 

The cost of the foil antenna is restricted to the BNC fitting and foil. You could probably get the foil from someone who has put these type of antennas in already.

[David Staten]

I gotta dumb question:

 

What about just making a glide slope (foil) antenna nested on the bottom of the canard. They are quite small. Any splitter is going to decrease the signal to your receiver which means less range.

 

The cost of the foil antenna is restricted to the BNC fitting and foil. You could probably get the foil from someone who has put these type of antennas in already.

Not a dumb question at all.. we've got the glide slope antennae on the floor of the velocity.. one nav antenna in the wing.. the other on the back of the floor of the fuse... all foil.

 

no diplexer needed. no splitting of signal and signal loss.. Just foil.. glass, toroids, coax and tape.

 

And this is on a dual ILS setup (and marker beacon antenna on the keel too, just for grins)

[argoldman]

Not a dumb question at all.. we've got the glide slope antennae on the floor of the velocity.. one nav antenna in the wing.. the other on the back of the floor of the fuse... all foil.

 

no diplexer needed. no splitting of signal and signal loss.. Just foil.. glass, toroids, coax and tape.

 

And this is on a dual ILS setup (and marker beacon antenna on the keel too, just for grins)

Actually, my post was in the line of a suggestion with canard in cheek. I, indeed have my VOR and GS nested on the bottom of my canard. The only problem that I ran in to was when mounting the BNC connector for one of them (can't remember which one) while measuring where the bulkhead would be, and giving clearance for the thickness of same, the BNC mounting flange interfered with the bulkhead when installing and removing the airfoil,making placement and removal of the canard difficult.

 

For those of you thinking of putting your antennas on the canard (recommended) be aware that when the canard is removed it must move forward and be rotated upward. Keep the BNC away from that arc.