transponder antenna

[Rodeo John]

What is better the blade type or the rod type ? Just put a smooth belly on my 66 E . And would like to know witch antenna work best ? 

[sleepingsquirrel]

I believe the blade type actually offers less drag, just be careful to align it with the direction of flight otherwise it doesn't. The rod type with a ball can be mounted without regard to the direction of flight the drag is the same.

[KSMooniac]

Agree with the squirrel.  I just swapped my rod & ball for a blade and had to over-size my mounting holes as my first attempt left it askew a bit.  If you have the fiberglass belly, the least-drag solution would be to put the antenna *inside* the belly, which is what I would do if I were you!

[N201MKTurbo]

You need a ground plane for the antennas for them to work correctly. The ground plane needs to extend in all directions at least the length of the antenna. bigger is better. You cane use an aluminum sheet metal plate on the inside, or aluminum tape. If you use tape use a meter to verify that all the pieces are electrically connected.

[Piloto]

The blade type is less prone to icing and shorting from exhaust carbon deposits. Rod type antennas has to be cleaned often, specially if located behind the engine exhaust.

José

[sleepingsquirrel]

Anyone know why the ball is important on the rod type?

The AV-22 is a rod style transponder antenna utilizing its BNC connector for mounting to the airframe. The antenna is designed to operate at speeds up to 350 mph and altitudes up to 50,000 feet. It has a drag force of 0.41 lbs @ 250 mph.  The AV-74 (.425 Stud Length) & the AV-74-1 (.800 Stud Length) are a broadband blade type antenna for transponders or DME application. The antenna housing is constructed of an acrylonitrile-styrene-acrylic (ASA) shell. The white color allows maximum performance without losses due to color pigments or unseen dirt. The antenna is supplied with cellular neoprene mounting pad and hardware. The antenna is designed to operate at speeds up to 350 mph and altitudes up to 50,000 ft. It has a drag force of 0.09 lbs @ 250 mph.

 

Edited October 8, 2015 by sleepingsquirrel

[carusoam]

Minimizes the pain felt when it gets bumped into...?

-a-

[sleepingsquirrel]

Eye poker preventer ,I see!

Here's a good reason to keep that old ADF sense wire antenna!

 

 

Edited October 8, 2015 by sleepingsquirrel

[tony]

Back when we only had AM radio to listen to, the ball was put on the end of the antenna to minimize static discharge which was heard in the reviewer as a pop. 

[OR75]

if you ever decide to use the Transponder ES to be ADS-B compliant, you will need a blade type of antenna

 

[RobertGary1]

The rod style has a magnetic attraction that causes those working under the plane to bump it and break it. I switched to the blade which is much stronger against bumping. 

-Robert

[N601RX]

I used copper tape and an aluminum sheet to make the ground planes.  It worked out very well. The ground plane needs to be at least a 1/4 wavelength if possible.   The aluminum sheet worked good for the DME, but copper tape worked well for the com antenna.  I looked at the radiated pattern on our OATS track at work and the pattern was fairly uniform. Other than the marker beacon I decided not to put the antennas under the fiberglass. Anywhere under the fiberglass they will be in close proximity to metal rods on each side and may be subject to shadowing or other interference.  

Also take the time to paint the underside of the fiberglass with a heavy epoxy.  It will prevent oil from soaking in and makes cleaning once a year easy.

Edited October 12, 2015 by N601RX