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VOR/GS Antenna

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jtpackard(at)usfamily.net
Guest

Posted: Tue Jun 19, 2007 8:06 am Post subject: VOR/GS Antenna

Can anyone explain why some VOR "cat whisker" antennas are mounted with the 

open end of the 'V' facing forward  and some facing aft?  Is there a 

difference in reception quality and/or drag characteristics?  Secondly, is 

the polyester lamination over the steel for improved precipitation static 

protection worth an extra $60?  Thanks for any answers posted.

TPackard



--- http://USFamily.Net/dialup.html - $8.25/mo! -- http://www.usfamily.net/dsl.html - $19.99/mo! ---

rhdudley1(at)bellsouth.ne
Guest

Posted: Tue Jun 19, 2007 8:35 am Post subject: VOR/GS Antenna

TPackard,

I have been told that the orientation is a matter of preference though 

the reception pattern ahead is slightly better with the tips pointing 

forward. I think many prefer the appearance with the tips pointing aft. 

(looks more aerodynamic:)

Richard Dudley

-6A flying (with tips pointing aft)



jtpackard(at)usfamily.net wrote:



 	  Quote: 	
		   



 Can anyone explain why some VOR "cat whisker" antennas are mounted 

 with the open end of the 'V' facing forward  and some facing aft?  Is 

 there a difference in reception quality and/or drag characteristics?  

 Secondly, is the polyester lamination over the steel for improved 

 precipitation static protection worth an extra $60?  Thanks for any 

 answers posted.

 TPackard



 --- http://USFamily.Net/dialup.html - $8.25/mo! -- 

 http://www.usfamily.net/dsl.html - $19.99/mo! ---

earl_schroeder(at)juno.co
Guest

Posted: Tue Jun 19, 2007 9:52 am Post subject: VOR/GS Antenna

I heard once that the forward facing whiskers were to protect the eyes

of the public [and unaware pilots]...

Can anyone explain why some VOR "cat whisker" antennas are mounted with

the 

open end of the 'V' facing forward  and some facing aft?  Is there a 

difference in reception quality and/or drag characteristics?

bobf(at)feldtman.com
Guest

Posted: Tue Jun 19, 2007 2:37 pm Post subject: VOR/GS Antenna

shouldnt matter - precip/icing might be an issue/ appearance probably drives it. main thing is it should be horizontally polarized while the comm antennas should be vertically polarized

  

 bobf

 W5RF



 

 On 6/19/07, jtpackard(at)usfamily.net (jtpackard(at)usfamily.net) <jtpackard(at)usfamily.net (jtpackard(at)usfamily.net)> wrote:  [quote]--> AeroElectric-List message posted by: <jtpackard(at)usfamily.net  (jtpackard(at)usfamily.net)>



Can anyone explain why some VOR "cat whisker" antennas are mounted with the

open end of the 'V' facing forward  and some facing aft?  Is there a

difference in reception quality and/or drag characteristics?  Secondly, is 

the polyester lamination over the steel for improved precipitation static

protection worth an extra $60?  Thanks for any answers posted.

TPackard



--- http://USFamily.Net/dialup.html 

[b]

BobsV35B(at)aol.com
Guest

Posted: Tue Jun 19, 2007 4:25 pm Post subject: VOR/GS Antenna

Good Evening bobf and TPackard,

  

 May I suggest that consideration be given to using blade antennas?

  

 I have installed several sets with excellent results. They are relatively  low drag, handle precipitation well, have no issues with ice and nobody has  ever gotten an eye poked out by running into one.  

  

 While reception strength and pattern are not very important with modern  radios, the blades do provide excellently balanced reception throughout the  operating range. I generally have fed two VHF navigation receivers and two glide  slope receivers from one set of blades. All in all, very happy with the  results.

  

 Happy  Skies,



Old Bob

AKA

Bob Siegfried

Ancient Aviator

Stearman  N3977A

Brookeridge Air Park LL22

Downers Grove, IL 60516

630  985-8503



  

 In a message dated 6/19/2007 5:41:02 P.M. Central Daylight Time,  bobf(at)feldtman.com writes:

  	  Quote: 	
		     shouldnt matter - precip/icing might be an issue/ appearance probably    drives it. main thing is it should be horizontally polarized while the comm    antennas should be vertically polarized

    

   bobf

   W5RF



 

   On 6/19/07, jtpackard(at)usfamily.net (jtpackard(at)usfamily.net) <jtpackard(at)usfamily.net (jtpackard(at)usfamily.net)> wrote:        	  Quote: 	
		  -->      AeroElectric-List message posted by: <jtpackard(at)usfamily.net       (jtpackard(at)usfamily.net)>



Can anyone explain why some VOR "cat whisker" antennas are      mounted with the

open end of the 'V' facing forward  and some      facing aft?  Is there a

difference in reception quality and/or      drag characteristics?  Secondly, is 

the polyester lamination      over the steel for improved precipitation static

protection worth an      extra $60?  Thanks for any answers    posted.

TPackard

	


	


 



See what's free at AOL.com. 

  [quote][b]

nuckollsr(at)cox.net
Guest

Posted: Wed Jun 20, 2007 5:27 am Post subject: VOR/GS Antenna

At 05:49 PM 6/19/2007 +0000, you wrote:

   Distorting the classic linear dipole antenna by moving the ends

   forward or aft on the aircraft will have two significant effects.

   See:



http://www.tpub.com/content/neets/14182/css/14182_186.htm



   The straight dipole in free space will exhibit strong and

   equal responses to the broad sides of the dipole and very

   sharp nulls (near zero response) to the ends. Obviously,

   the "ideal" antenna would have equal and super responses

   all the way around the compass . . . but we don't live in

   a perfect world. Besides, in aircraft, we're MOST interested

   in VOR stations that lie on our path of flight.



   As soon as you distort the classic shape, the responses

   to the broad sides will change . . . one gets weaker while the

   other one gets stronger. This doesn't continue without

   bounds . . . if you keep moving the free ends of the

   antenna closer together, the antenna morphs from an

   effective radiator/receptor of energy to a poorly

   terminated transmission line with exceedingly high

   SWR.



   At the same time the braodside responses are distorting,

   the nulls at the ends become less than "perfect" so

   your ability to utilize VOR stations that lie off your

   heading is improved.



   Whether there is advantage to bringing the tips

   forward or aft is mostly a matter of style. When

   you're flying the Victor Airways, the charts depict

   nav aid changeover points where it's recommended

   that you stop navigating on the station behind you

   and change to the station in front of you. This may

   or may not be at the half-way point. There are

   folks that spend many $killo$ of your tax money

   to survey these routes with the goal of optimizing

   performance based on signal strengths from the various

   facilities. These surveys account for intermediate

   obstructions and other effects of terrain.



   Bottom line is that for 99.9% of the way YOUR airplane

   is going to be used, the VOR antenna configuration

   is not going to be a key component of your recipe for

   success in completing the mission of the moment. I think

   I'd base antenna selection on cost and appearance

   in that order. Bob archer's wing tip antennas are strong

   contenders in this market. Only if Bob's product proves

   inadequate to YOUR tasks would I consider expanding the

   field of consideration for which antenna to use. Obviously,

   the v-whiskers are inexpensive and easy to install

   and attach to a feed line. Consider using a BALUN to

   improve on the interface between dipole and coax. See:



http://aeroelectric.com/articles/BALUN/Balun_Fabrication.html



   For those members of the List interested in some of the

   more esoteric aspect of our craft, cruise the website I

   cited above. Stoke the Next/Back links for a broad and

   well explained dissertation on antenna science. The same

   site has a wealth of other data of interest for the

   curious and motivated reader.



   Bob . . .

nuckollsr(at)cox.net
Guest

Posted: Wed Jun 20, 2007 7:15 am Post subject: VOR/GS Antenna

At 08:25 AM 6/20/2007 -0600, you wrote:



 	  Quote: 	
		  

<nuckollsr(at)cox.net>



At 05:49 PM 6/19/2007 +0000, you wrote:

   Distorting the classic linear dipole antenna by moving the ends

   forward or aft on the aircraft will have two significant effects.

   See:



http://www.tpub.com/content/neets/14182/css/14182_186.htm


	




   I thought I recognized some of the stuff in the link

   I cited. The Navy's Electricity and Electronics Training

   Series are available from the a variety of websites including

   my own. They are part of the downloadable CD materials which

   you can access at:



http://www.aeroelectric.com/CD/



   You'll need a high-speed internet connection to get these

   documents with any reasonable dispatch. They are big. But

   you can't beat the price for acquiring some excellent texts

   on matters electronics. I taught out of earlier versions of

   these documents at Great Lakes about 40 years ago.



   If push comes to shove, you can order the CD from us . . .

   or better yet, attend one of the seminars. You get the

   CD for free. If you DO have a way to conveniently download

   the CD, please duplicate and share with your local aviation

   enthusiasts. Our charge for the CD is a nuisance-fee. It's

   not our goal to turn a profit on the activity. The goal is

   to maximize availability of the offered materials to any folks

   who have an interest.



   You can get the individual Modules for this series of

   documents at:



http://www.phy.davidson.edu/instrumentation/NEETS.htm



   Download, share, learn and enjoy . . .

   Bob . . .

jtpackard(at)usfamily.net
Guest

Posted: Wed Jun 20, 2007 7:55 am Post subject: VOR/GS Antenna

Thanks for the suggestion Bob.

One question though.  I see the Comant CI-120 blade set for VOR/GS 

Navigation sells for approx. $800.  Do you know of any priced closer to the 

"cat whisker' style?

Thanks,

Tom Packard

Super Rebel 90%(you know what that means!) 



--- http://USFamily.Net/dialup.html - $8.25/mo! -- http://www.usfamily.net/dsl.html - $19.99/mo! ---

BobsV35B(at)aol.com
Guest

Posted: Wed Jun 20, 2007 8:15 am Post subject: VOR/GS Antenna

Good Morning Tom,

   

 No, I do not.

  

 The price is a major detriment.  

  

 I was using Dorne Margolin units until they raised their price into the  stratosphere. I then went to Comants and just last year installed a set of  Sensor Systems blades. They have a stainless steel insert in the leading edge  which MAY be helpful on unimproved strips.  Don't know yet. Those were  mounted below the stabilizer on a model E18S Twin Beech which frequents many out  of the way landing strips. 

  

 The cost factor IS terrible, but they work great!

  

 The "hidden in the wing tip" solution sounds great if it will work!

  

 If that is not an option, I would pop for the blades.

  

 Happy  Skies,



Old Bob

AKA

Bob Siegfried

Ancient Aviator

Stearman  N3977A

Brookeridge Air Park LL22

Downers Grove, IL 60516

630  985-8503



 In a message dated 6/20/2007 10:57:56 A.M. Central Daylight Time,  jtpackard(at)usfamily.net writes:

  	  Quote: 	
		  -->    AeroElectric-List message posted by:    <jtpackard(at)usfamily.net>



Thanks for the suggestion Bob.

One    question though.  I see the Comant CI-120 blade set for VOR/GS    

Navigation sells for approx. $800.  Do you know of any priced closer    to the 

"cat whisker' style?

Thanks,

Tom Packard

Super Rebel    90%(you know what that means!) 

	


 



See what's free at AOL.com. 

  [quote][b]

nuckollsr(at)cox.net
Guest

Posted: Wed Jun 20, 2007 8:46 am Post subject: VOR/GS Antenna

At 10:51 AM 6/20/2007 -0500, you wrote:



 	  Quote: 	
		  



Thanks for the suggestion Bob.

One question though.  I see the Comant CI-120 blade set for VOR/GS 

Navigation sells for approx. $800.  Do you know of any priced closer to 

the "cat whisker' style?

Thanks,

Tom Packard

Super Rebel 90%(you know what that means!)


	


   No, blade antennas are relatively simple with respect

   to the antenna part . . . Bob archer could easily

   fabricate a suitable pattern on a piece of copper clad

   but a couple of 1/16th inch thick, fiberglas "flappers"

   bolted to each side of your vertical fin would not draw much

   praise for style. The expensive part of building a blade

   antenna is to mold a stylistic, robust but LIGHT enclosure

   around it. The tooling is not cheap, the process not trivial.



   Hence, demand for such antennas has been decidedly low

   in spite of the fact that they work well and look good.

   A set of blades would also be heavier than a v-whisker

   and this weight sets waaaayyy back on the moment arm for

   your C.G. calculations.



   Finally, given the inexorable fade of VOR as a primary

   mode of navigation, it's my suggestion that you figure

   out a way to get SOME VOR capability on board with a minimum

   of expense and effort. I.e. don't bust yer buns to

   achieve an optimized capability. VOR no longer

   figures in the best-we-know-how-to-do. The v-whisker is

   a mild compromise over blades in terms of performance.

   The wing tip antennas are a bit more compromised yet

   but sales of those devices is strong.  I've not heard

   of any one replacing them with another technology

   'cause it doesn't perform well enough to accommodate

   the mission.



   Since I bought my first hand-held GPS in 1995, I've not

   turned on a VOR receiver for any purpose other than

   to demonstrate it to someone who is along for the ride

   or to fiddle with while watching the ground go by.



   Bob . . .



        ----------------------------------------

        ( "Physics is like sex: sure, it may   )

        ( give some practical results, but     )

        ( that's not why we do it."            )

        (                                      )

        (                 Richard P. Feynman   )

        ----------------------------------------

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