Com Antenna Mount

[Grant S. Bailey]

My fuselage is very close to being ready to cover. I just have to fabricate and install a com antenna mount and ELT antenna mount. Anyone have any suggestions for the proper size of groundplates and ideal locations, or pictures of their mounts? I assume the groundplate should be grounded to aircraft ground? The com antenna that came with the airplane is a stainless steel bent whip. It does not have a BNC connector on the bottom, just a threaded end to the stainless steel antenna rod?? Should I buy a new antenna?

Any tips or suggestions welcome. I won't be purchasing a panel mount radio until the airplane has been test flown.

[lktiller]

The antenna is fine as long as you have the insulator it mounts through. Solder-lug center wire of the coax, mounts under the nut at base of antenna. Coax shield mounts to gnd plane.
Many options for com antenna and they all work fine. Even mounted inside the fuselage.
Maximum range with ground plane about 18" dia.

I have same antenna mounted in the bottom of the boot cowl. A few inches forward of the rudder pedals. Pointed down.
Coax from ant. to door post and up to hand-held Icom clipped on the glove box door. Adapter cables to battery intercom, PTT, and headsets.

[TimHicks]

I use a ICOM handheld with an externally mounted antenna. The antenna is mounted above the cabin centered on the fuselage and about mid chord of the wing. The antenna is straight (no bend in it like yours) at about 45degree angle to the horizon in level flight. I've always been pleasantly surprised at how good the handheld works. However, sometimes when I'm too close to another airplane I have trouble communicating with them. For example when flying in formation (not always, just sometimes) or on the ground taxiing. I have to be within a couple of wingspans to have this problem but that's usually when I really want to make sure that we understand each other!

I wonder if my antenna mount location is part of this problem. Perhaps the wing and/or fuselage blanket the line of sight and reduce effectiveness

Tim

[lktiller]

Tim,
If you have trouble understanding them, then your receiver front-end is being swamped by their signal. Put the rubber antenna on the Icom and try.

My Icom receiver is distorted if my battery gets low.

[Robert Lees]

A ground plane is not required if the antenna is grounded to the steel fuselage, either at the dome light (is yours attached there, Tim?) or like mine, at the front spar-fuselage attachment. Then the whole fuselage frame acts as a ground plane.

The problem with under-fuselage comm antennae seems to be transmissions on the ground (quite important to get the ATIS).

We all use Icom handhelds here in England, with straight whip antennae grounded to the fuselage (an old ELT antenna works great) and 12V gel cell power supplies. Photo of installation of antenna at www.Taylorcraft.org.uk/aerial1.jpg and www.Taylorcraft.org.uk/aerial2.jpg . Full text and photos at www.Taylorcraft.org.uk/Brey_rebuild2.htm (about4/5 the way down the page). No problem receiving or transmitting over >100 mile range.

I got two-way with a pal who was on the climb-out of Paris CDG one day; I was taxying on the ground here in the centre of England. We had quite a chat, OK he was at in a jet at FL270, but still pretty good for my little Icom, over 250 miles.

Like Larry, the transmission gets distorted if the batteries get low. But even in tight formation, Tim, no transmit/receive problems. Even within 1/4 wingspan!

Grant: I have seen some neat ELT antenna installations on some L2's, they put them inside the glazing of the "greenhouse"; perhaps you could adapt this principle and have you ELT antenna adjacent to the rear windows?

Rob

[Grant S. Bailey]

Thanks for the replies and suggestions guys. I do have the insulators for my antenna so will go with it as a first try. I think I will stick with a standard mount on top of the fuselage between my skylights and ground to the frame as Robert has suggested.

Pictures of my rebuild are on the gallery (C-FXSU Rebuild).

[Jim Schmidt]

L-2 antenna placements

Rob, Could you elaborate on the neat antennae placements in L-2 Greenhouse. I nead to intall a com antenna in my L-2A

Originally posted by Robert Lees
A ground plane is not required if the antenna is grounded to the steel fuselage, either at the dome light (is yours attached there, Tim?) or like mine, at the front spar-fuselage attachment. Then the whole fuselage frame acts as a ground plane.

The problem with under-fuselage comm antennae seems to be transmissions on the ground (quite important to get the ATIS).

We all use Icom handhelds here in England, with straight whip antennae grounded to the fuselage (an old ELT antenna works great) and 12V gel cell power supplies. Photo of installation of antenna at www.Taylorcraft.org.uk/aerial1.jpg and www.Taylorcraft.org.uk/aerial2.jpg . Full text and photos at www.Taylorcraft.org.uk/Brey_rebuild2.htm (about4/5 the way down the page). No problem receiving or transmitting over >100 mile range.

I got two-way with a pal who was on the climb-out of Paris CDG one day; I was taxying on the ground here in the centre of England. We had quite a chat, OK he was at in a jet at FL270, but still pretty good for my little Icom, over 250 miles.

Like Larry, the transmission gets distorted if the batteries get low. But even in tight formation, Tim, no transmit/receive problems. Even within 1/4 wingspan!

Grant: I have seen some neat ELT antenna installations on some L2's, they put them inside the glazing of the "greenhouse"; perhaps you could adapt this principle and have you ELT antenna adjacent to the rear windows?

Rob

[Dick Huish]

Jim, the ELT antenna is a lot different in size than a Comm antenna and will work well in the greenhouse. The Comm antenna is a lot bigger and won't work well if located inside the window structure. I have found the mounting the Comm antenna abovr the rear spar carry thru on the window frame works well. I did one where I mounte the antenna above the fromt spar carry thru. I prefer the rear one better. IMHO, Dick

[Jim Schmidt]

I will take a look at that location. I tried a temporary mount last year on top of the greehouse further aft where all the tubes intersect and that worked ok.

Originally posted by Dick Huish
Jim, the ELT antenna is a lot different in size than a Comm antenna and will work well in the greenhouse. The Comm antenna is a lot bigger and won't work well if located inside the window structure. I have found the mounting the Comm antenna abovr the rear spar carry thru on the window frame works well. I did one where I mounte the antenna above the fromt spar carry thru. I prefer the rear one better. IMHO, Dick

[AlvinMcIver]

Although this thread appears to have come to an end, I thought I'd post my experience with com antennas. I use a Yaesu Aviator Pilot and fly out of a class D airport. When I first brought my Taylorcraft home, I was using the rubber antenna. Although I could hear the ATIS and tower, the tower could only tell that someone was trying to contact them and they did decipher that it was a Taylorcraft. Bless their souls, they asked whether it was my intention to land and to acknowledge in the affirmative with two clicks ("click, click"). The then told me to report 3 SW and to acknowledge with two clicks ("click, click"). Before I could report 3 SW, the tower cleared me to land ("click, click"). After landing, for whatever reason, ground could understand me and cleared me to taxi to my hangar. Thereafter ensued a month of experimenting with various antennas and placements. Finally, what worked was a stainless steel bent whip antenna (RAMI AV-534 model -- Aircraft Spruce had them for $44.50) which I mounted by drilling a hole in the metal band covering the gap between the wing and fuselage behind the rear spar attach point which allowed me to run the cable between the wing and fuselage forward until I could thread it into the cockpit. I was told the metal band acted as the ground plane (the square inches are more than enough) and I have had no problems with receiving (40-50 miles) or transmitting (15-25 miles). I do have problem with the static (if it wasn't quite so loud, I would call it white noise) when neither receiving nor transmitting. Almost anyone with whom I have spoken has said that they believe it is from the unshielded plugs, wires and magnetoes. I'm about ready to give up, but would like others thoughts or suggestions. Thanks.

[Forrest Barber]

I used a radio shack antenna $6.95 about 15 years ago out the bottom of the boot cowl on the left side. I used a Comm-Spec handheld ( which has fantasatic noise rejection) and trimmed the antenna length using a meter to mid range of 118 - 136 at about 126 and had great reception & xmit capability . Get a good radio guy to help you out . The noise rejection of the unit is the answer......

[Robert Lees]

Clicks

Well I thought two clicks meant "no", one click for "yes"

Rob