FW: Transponder Ant. was Re: REFLECTOR:anntenas

Brian Michalk reflector@tvbf.org
Fri, 11 Apr 2003 15:36:20 -0500


-----Original Message-----
From: reflector-owner@tvbf.org [mailto:reflector-owner@tvbf.org]On
Behalf Of richard riley
Sent: Friday, April 11, 2003 3:33 PM
To: reflector-admin@tvbf.org
Subject: Re: Transponder Ant. was Re: REFLECTOR:anntenas


(sorry I'm sending this through the admin instead of 
straight to the group, but where I am I don't have the 
ability so send from my normal account, so I'm figuring it 
will be bounced as from a non-subscriber)

I had this conversation a couple of years ago with Jim 
Wier.  More is not better.  What you really want is a 1/4 
wave.  The size of a reflector for 1/4 wave is kind of 
odd, so what you do is make up a hex or a square 
reflector, with the distance to the points a little to 
long, and to the center of the flats a little too short. 
 SOMEWHERE along the edge is the 1/4 wave distance.  The 
shape I finally settled on is a hex with bent down edges. 
 That shields more of the pattern from your butt, but 
because of the slant distance it makes the dimentions more 
complex:

Cut a hexagon out of .025 aluminum.  It's 5.9" across at 
the flats, 6.66 across at the points.

Out of each point cut out a wedge, 90 degrees to the 
flats, .5" deep.  Fold down a .5" wide lip at 90 degrees 
to the plate, all the way around, so it's an inverted 
hexagonal aluminum candy dish.

The slant distance from the center of the dish to the lip 
is 2.5" at the center of a flat, and 2.87" at a point, so 
somewhere between the two is the real 1/4 wave distance.




On Fri, 11 Apr 2003 14:33:11 -0400
  "Fred Marconi" <fmarconi@bellsouth.net> wrote:
>That should do I erred on the more the better.  6" is 
>minimum.
>
>Fred
>
>----- Original Message -----
>From: "Alexander Balic" <alex157@direcway.com>
>To: <reflector@tvbf.org>
>Sent: Friday, April 11, 2003 10:43 AM
>Subject: RE: Transponder Ant. was Re: REFLECTOR:anntenas
>
>
>> mine is 6" dia,with two small flats on it to fit under 
>>the battery tray
>>
>> -----Original Message-----
>> From: reflector-admin@tvbf.org 
>>[mailto:reflector-admin@tvbf.org]On
>> Behalf Of Scott Derrick
>> Sent: Friday, April 11, 2003 7:38 AM
>> To: reflector@tvbf.org
>> Subject: Re: Transponder Ant. was Re: REFLECTOR:anntenas
>>
>>
>> Really that big?
>>
>> I think the one in the strake is 3x3
>>
>> Scott
>>
>> Fred Marconi wrote:
>> > 9" X 9" WOULD DO NICELY.
>> >
>> > FRED
>> > ----- Original Message -----
>> > From: "Scott Derrick" <scott@tnstaafl.net>
>> > To: <reflector@tvbf.org>
>> > Sent: Friday, April 11, 2003 9:12 AM
>> > Subject: Transponder Ant. was Re: REFLECTOR:anntenas
>> >
>> >
>> >
>> >>I'll second Wayne's "DO NOT" for the transponder. Mine 
>>is in the strake
>> >>in the outside wing bolt hole space.  I get periodic 
>>complaints from ATC
>> >>about intermittent transponder.  I think I'll purchase 
>>another antenna
>> >>and try mounting one closer to the transmitter.
>> >>
>> >>I don't want it out side though, don't have any 
>>external antennas now,
>> >>and don't want any.
>> >>
>> >>Where's a good spot in a standard RG?  I was thinking 
>>about mounting it
>> >>to the bottom of the rear seat?
>> >>
>> >>How big does the ground plane need to be?
>> >>
>> >>My GPS antenna is mounted to the inside of the nose 
>>access door, 4 feet
>> >>of cable and works great.
>> >>
>> >>Scott
>> >>
>> >>Wayne Lanza wrote:
>> >>
>> >>>
>> >>>Regarding the antennas, our experience at the 
>>builders center points to
>> >>>the following:
>> >>> > Transponder ANT = between the firewall and gear 
>>bulk head, on center
>> >>>line. DO NOT
>> >>>put this ANT out in the strake, many transponders 
>>don't like to drive
>> >>>this much wire!
>> >>> > GPS = on top of the landing light or on top of the 
>>canard, keep this
>> >>>wire under 8' long.
>> >>> > Marker Beacon = Inside or outside of the keel, or 
>>on the floor near
>> >>>the keel. Locate
>> >>>the foil such that you don't tear it up when 
>>upholstering or mounting
>> >>>the seats...
>> >>> > Glide Slope = On the floor under the copilot front 
>>seat area.
>> >>> > AM/FM = Not too critical, string a 23" piece of 
>>the ANT wire (center
>> >>>conductor only)
>> >>>across the under side of the structure in front of 
>>the canopy. Make
>sure
>> >>>that the pitch
>> >>>trim spring doesn't interfere.
>> >>> > ELT = Mount the ELT to the floor between the gear 
>>bulk head and the
>> >>>keel bulk head
>> >>>on the copilot side. Run two 23" foils on a diagonal 
>>centered at the
>> >>>fuselage joint, the
>> >>>angle of the foils is such that they are fairly 
>>straight (they might
>> >>>wrap onto the ceiling).
>> >>>This is not super critical, but this antenna should 
>>be vertically
>> >>>mounted not horizontal!
>> >>>Use the torroids and connect the coax braid to the 
>>lower foil. Secure
>> >>>foils, torroids and
>> >>>the end of the lead in coax with 1 ply of bid. This 
>>needs to be
>> >>>shock/impact secured.
>> >>> > ADF = I've heard of them :-)
>> >>>
>> >>>In general, use the correct type of coax (not TV wire 
>>or solid center
>> >>>conductor), use the
>> >>>proper BNC terminals and appropriate tools. Keep the 
>>coax runs short
>and
>> >>>secure.
>> >>>
>> >>>Fly Safe,
>> >>>Wayne Lanza
>> >>>Composite Design, Inc.
>> >>>(electrical weenie at the Velocity Builder's Center)
>> >>>____________________________________________________________________
>> >>>On Friday, April 11, 2003, at 06:37 AM, Lynn Gallup 
>>wrote:
>> >>>
>> >>>    Noel,
>> >>>    As near as possible, I followed the suggestions 
>>in the Velocity
>> >>>    manual. After 185 hours flying my airplane in a 
>>wide variety of
>> >>>    circumstances I can pronounce perfect operation 
>>of my nav & com
>> >>>    radios, localizer & glideslope, marker beacon 
>>receiver and
>> >>>    transponder. Even the ADF works acceptably 
>>although its range is a
>> >>>    little short. The GPS would benefit from 
>>shielding or a slight
>> >>>    relocation as it will blank out if one of the nav 
>>receivers is
>tuned
>> >>>    to a particular VOR frequency. (Leakage of nav's 
>>IF frequency
>signal
>> >>>    out of the localizer antenna overcomes the 
>>satellite signals.)
>> >>>
>> >>>    Mine is a hatch door, long wing, RG. The antenna 
>>locations are:
>> >>>
>> >>>    Com antennas - In the tip sails.
>> >>>    Nav antenna - One shared antenna on top of 
>>fuselage about four
>> >>>    inches forward of engine bulkhead.
>> >>>    Marker beacon antenna - Along right side about 
>>two inches below
>> >>>    windows.
>> >>>    Transponder antenna - Bottom of fuselage below 
>>right rear seat.
>> >>>    ADF antennna - Bottom of fuselage below left rear 
>>seat.
>> >>>    Localizer antenna - On canard top surface, 
>>center-line of fuselage.
>> >>>    GPS antenna - Front of canard top, centered. 
>>Forward of localizer
>> >>>    antenna. It should be remounted under the top of 
>>the fuselage above
>> >>>    the localizer antenna.
>> >>>
>> >>>    Regards,
>> >>>    Lynn
>> >>>    =====================
>> >>>    At 11:46 PM 4/10/2003 Thursday, you wrote:
>> >>>
>> >>>
>> >>>    Now that it's finally starting to warm up, I'm 
>>doing the planning
>> >>>    for my summer project... The wings / canard.
>> >>>    I realize that antenna placement is variable, 
>>But...
>> >>>    What do I really need? Do I need a Com and Nav in 
>>each wing?
>> >>>    Where's the best place for a glideslope antenna. 
>>The keel was
>> >>>    already down when I got the kit.
>> >>>    I assume the transponder would be best on the 
>>floor, and the gps on
>> >>>    the ceiling.
>> >>>    What about something for the am/fm?
>> >>>    I've seen Don's elt antenna on the main wingspar 
>>shearweb, and it
>> >>>    looked pretty survivable.
>> >>>
>> >>>    What's popular / what's practical
>> >>>
>> >>>    Noel 3suv103
>> >>>
>> >>>
>> >>
>> >>
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>> >
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>>
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