---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 07/22/20: 5 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:12 AM - Re: DIY LOC/VOR_G.S. Antenna (merlewagner2) 2. 11:34 AM - Re: Re: DIY LOC/VOR_G.S. Antenna (Robert L. Nuckolls, III) 3. 12:19 PM - Re: best practices for Molex? (prestonkavanagh) 4. 05:07 PM - Transponder and/or ADSB Antenna Installation and Radiation () 5. 09:19 PM - Re: Transponder and/or ADSB Antenna Installation and Radiation (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 05:12:07 AM PST US Subject: AeroElectric-List: Re: DIY LOC/VOR_G.S. Antenna From: "merlewagner2" I agree the VHF antenna (without the GS antenna ears) will work very well for receiving the GS freqs. I wanted to see how the performance could be enhanced with the antenna tuned to the different bands. The only verifiable method to prove this would be testing the antenna with and without the GS elements. I just don't have the time to do this at the moment. A future test. I am going crazy getting the Tailwind ready for it's first flight this weekend. Everytime I try something another problem arises. Guess that is why this is experimental aviation. I do know that trimming the GS elements adjusted the antenna VSWR to the freq range I wanted. I did this in real time by watching my NANOVNA output while trimming. So the ears do have a major impact on the freq band. I also ran the antenna to an antenna multi-coupler versus the splitter you show. This also guarantees improved reception as the signal level is reduced with the splitters. -------- KC1DNJ General Radiotelephone Commercial SEL A&P Building scale P51, rebuilding Tailwind W10 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=497393#497393 ________________________________ Message 2 _____________________________________ Time: 11:34:07 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: DIY LOC/VOR_G.S. Antenna At 07:11 AM 7/22/2020, you wrote: > > >I agree the VHF antenna (without the GS antenna ears) will work very >well for receiving the GS freqs. > >I wanted to see how the performance could be enhanced with the >antenna tuned to the different bands. The only verifiable method to >prove this would be testing the antenna with and without the GS >elements. I just don't have the time to do this at the moment. A future test. I'm planning an experiment centered on Jim Wier's suggestion for a dual band 121.5/406 Mhz ELT antenna. These two frequencies are not harmonically related. I've got the elements built. Planning to explore balun options too. I'll document the exercise and post here. > I am going crazy getting the Tailwind ready for it's first flight > this weekend. Everytime I try something another problem arises. > Guess that is why this is experimental aviation. Sounds like the engineering flight test hangar at Beech! >I do know that trimming the GS elements adjusted the antenna VSWR to >the freq range I wanted. I did this in real time by watching my >NANOVNA output while trimming. So the ears do have a major impact on >the freq band. When I get the ELT experiment done, I'll repeat repeat your VOR-LOC/GS experiment and see what I get. We'll compare notes. >I also ran the antenna to an antenna multi-coupler versus the >splitter you show. This also guarantees improved reception as the >signal level is reduced with the splitters. Be wary of distribution amplifier type couplers. The 'ideal' gain is zero. I.e. same output for a given input at the frequencies of interest. Keep in mind that our navigation equipment is sorta tailored to be compatible with legacy practices for transmitted signals, typical (passive) antennas, reasonably low loss coax, etc. Adding active devices into the feedline has some risk for (1) overloading the receiver(s) on the ILS system and/or (2) increasing risks for inter-modulation interference of desired signals by unrelated/undesired signals. Study the specs for your chosen device for assurance that the thing adds value and does not add risk. Bob . . . ________________________________ Message 3 _____________________________________ Time: 12:19:56 PM PST US Subject: AeroElectric-List: Re: best practices for Molex? From: "prestonkavanagh" Thanks to all, for both the pin gender and comments on Molex. I'll revise accordingly. Cheers, PK -------- PBK3 PA-12, BD-4, RV6a, gliders Read this topic online here: http://forums.matronics.com/viewtopic.php?p=497395#497395 ________________________________ Message 4 _____________________________________ Time: 05:07:00 PM PST US From: Subject: AeroElectric-List: Transponder and/or ADSB Antenna Installation and Radiation Greetings, I am a member of a composites aircraft community and the question came up (again) about the installation location of these high frequency antennae. Assuming that the airplane is build of mostly fiberglass (and not carbon fiber) there is the temptation to mount these two antennae inside the airframe so that the antennae are fully enclosed by the fuselage and the airplane is more aerodynamic.sounds good so far.and each antenna will have a ground plane. So the questions are: -Is the ground plane better to be square/ round/ or hexagon/ or some other shape? -If the diameter of the ground plane cannot be exactly a square and the same dimension as indicated on the installation guide what is the problem(s) with it being slightly to wide or slightly too narrow than spec, or if the antenna is not installed in the exact center? -The book says the two antennae should be mounted at least two feet from each other so what if they were installed closer.or even co-located on the same ground plane? -What about mounting these masts near human body parts (ouch)? -What about mounting these masts near other avionics or other electrical equipment? Thanks everyone for you kind assistance!!! ________________________________ Message 5 _____________________________________ Time: 09:19:33 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Transponder and/or ADSB Antenna Installation and Radiation > >So the questions are: > >-Is the ground plane better to be square/ round/ >or hexagon/ or some other shape? Why not eliminate the need for ground planes with vertically polarized dipoles mounted to inside surfaces of empannage? https://tinyurl.com/y3w4hf8y >-If the diameter of the ground plane cannot be >exactly a square and the same dimension as >indicated on the installation guide what is the >problem(s) with it being slightly to wide or >slightly too narrow than spec, or if the antenna >is not installed in the exact center? ditch the ground planes >-The book says the two antennae should be >mounted at least two feet from each other so >what if they were installed closer=85or even co-located on the same ground plane? Mount one on left side forward, the other right side aft. Getting separation shouldn't be a problem. >-What about mounting these masts near human body parts (ouch)? > >-What about mounting these masts near other >avionics or other electrical equipment? back in the tail? 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