VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #11  
Old 02-14-2020, 01:59 PM
N941WR's Avatar
N941WR N941WR is offline
 
Join Date: Jan 2005
Location: SC
Posts: 12,686
Default

So, which wing is best to install the Archer antenna, Left or Right?

In the Right wing you have an autopilot servo and in the left you have the controller for the pitot heat (Dynon in my case). I plan on installing mine in the left wing, thinking the pitot heat controller would give less interference than the AP servo.

Thoughts?
__________________
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
Reply With Quote
  #12  
Old 02-14-2020, 04:59 PM
Pilot135pd's Avatar
Pilot135pd Pilot135pd is online now
 
Join Date: Jan 2019
Location: Ben Wheeler, TX
Posts: 829
Default

Quote:
Originally Posted by BlackhawkSP View Post
First of all, the GS frequencies are 329 to 335 MHZ. If you used the listed 234/113, that's why your math is not working out.

Using the formula of WAVELENGTH X FREQUENCY = SPEED OF LIGHT (C) and run the numbers for the middle of the band for GS frequencies, the math works out as 35.55 inches for a full wave antenna. This makes the exact length of the stripped portion of a 1/2 wave antenna at 17.78 inches. The 16 to 17 inches of the stripped center conductor of a piece of coax stuffed down the gear leg of my 8 has worked perfectly for years.


Would do it again in a second:-).

I had to get the calculator out and shake off a few cobwebs in the brain on that one:-)....
You misunderstood my post. At the beginning of my post I said I was making a VOR and GS antenna.

I wrote 234/113 Mhz (middle of frequency range) = 2.07 feet not 16" !

where the 113 Mhz is the center of the VOR range 108 - 117.95

SO

234 divided by 113 = 2.07 feet x 12 = 24.84 inches for a VOR ( radiating element ) dipole.


If I were going to make it for the GS only I'd use the shorter antenna :

234/332 Mhz (332 is the middle of 329 to 335 Mhz) = 0.70 feet x 12 = 8.45 inches for the radiating element of the 1/2 wave dipole.

So my numbers were correct for a VOR antenna where apparently the 16" is what some are using for the GS only antenna. At least that cleared up where they got the 16".
__________________
RV-8 N52VM: Dynon D-180, Autopilot, Titan 0-360A1A, Hartzell C/S, INS-429 IFR, WingX & Stratux for backup & ADS-B IN. Enjoying life while building a FREE campsite for pilots www.facebook.com/VacaMooAirport/

Exempt by 3 out of the 10 ways but I still donated.
Reply With Quote
  #13  
Old 02-14-2020, 07:11 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 6,253
Default

Quote:
Originally Posted by N941WR View Post
So, which wing is best to install the Archer antenna, Left or Right?
Thoughts?
Neither the heat controller nor the servo should generate appreciable radio frequency interference.
Reply With Quote
  #14  
Old 02-14-2020, 09:22 PM
BlackhawkSP's Avatar
BlackhawkSP BlackhawkSP is offline
 
Join Date: Jun 2011
Location: Indianapolis
Posts: 192
Default

Quote:
Originally Posted by Pilot135pd View Post
You misunderstood my post. At the beginning of my post I said I was making a VOR and GS antenna.

I wrote 234/113 Mhz (middle of frequency range) = 2.07 feet not 16" !

where the 113 Mhz is the center of the VOR range 108 - 117.95

SO

234 divided by 113 = 2.07 feet x 12 = 24.84 inches for a VOR ( radiating element ) dipole.


If I were going to make it for the GS only I'd use the shorter antenna :

234/332 Mhz (332 is the middle of 329 to 335 Mhz) = 0.70 feet x 12 = 8.45 inches for the radiating element of the 1/2 wave dipole.

So my numbers were correct for a VOR antenna where apparently the 16" is what some are using for the GS only antenna. At least that cleared up where they got the 16".
My bad !! Sorry. I assumed you were using the Bob Archer antenna, which works great for the VOR.
__________________

Larry Anderson
Indianapolis
RV-Super 8 N88XT SOLD
RV-10 QB N38LA Flying
Helicopter Instructor Pilot
Standardization I.P.
Instrument Examiner
U.S. Army Retired
EMS Pilot for LifeLine
At IU Health Retired :-)
Although Exempt,
Donated for 2020
Reply With Quote
  #15  
Old 02-14-2020, 11:11 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 6,253
Default

Quote:
Originally Posted by Pilot135pd View Post
234 divided by 113 = 2.07 feet x 12 = 24.84 inches for a VOR ( radiating element ) dipole.
".
Just to be clear, a dipole for 113 MHz consists of two center fed radiating elements, each of which is 25”.
Reply With Quote
  #16  
Old 02-14-2020, 11:28 PM
Pilot135pd's Avatar
Pilot135pd Pilot135pd is online now
 
Join Date: Jan 2019
Location: Ben Wheeler, TX
Posts: 829
Default

Quote:
Originally Posted by BobTurner View Post
Just to be clear, a dipole for 113 MHz consists of two center fed radiating elements, each of which is 25”.
Technically the entire antenna is radiating but in this case I used the term to differentiate between the stripped part and the double shielded part. I didn't want to confuse anyone so I tried to keep it simple. When they strip the shield back and leave 24.85" clear (the part they'll show exposed ) then by default they'll have 24.85" of shield ( the other side of the dipole).

That's why in my post you see it says radiating element. The other side of the dipole (the shield in this case) is also 24.85" long.

Quote:
Originally Posted by Pilot135pd View Post
234 divided by 113 = 2.07 feet x 12 = 24.84 inches for a VOR ( radiating element ) dipole.
__________________
RV-8 N52VM: Dynon D-180, Autopilot, Titan 0-360A1A, Hartzell C/S, INS-429 IFR, WingX & Stratux for backup & ADS-B IN. Enjoying life while building a FREE campsite for pilots www.facebook.com/VacaMooAirport/

Exempt by 3 out of the 10 ways but I still donated.

Last edited by Pilot135pd : 02-14-2020 at 11:31 PM.
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 04:13 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.