A better indoor antenna than the supplied one?

[Bethsalem]

Hi All

I've had to move my setup and now have no access to putting up an external antenna for my mode S receivers. This means that I'm stuck with the indoor antennas that shipped with the units originally.

My question is, are there any indoor antennas which will give better reception than the supplied indoor ones?  Specifically, I had the BSBW-1090 Window Antenna in mind.

Stephen

[viking9]

Hi Stephen,

I haven't used the BSBW-1090 antenna, but I've been impressed with antennas supplied by Kinetic. I've got an SBS-3 in my study and a Beast which I use for mobile work with the whip antenna supplied with the SBS-3.

This whip antenna, mounted on a small frying pan on the inside window sill of my dining room (30 mtrs ASL), is giving me a max range of 248nm for aircraft between FL310 and FL390 today (weak to fair tropo ducting).  That's comparable to my SBS-3 with 0db gain antenna mounted on the chimney.

Tom

[shakysen]

Hi Stephen. I followed Toms suggestion about the ground plane idea It works a treat. Infact I've cut another ali 12ins dia disk out.Its going on the external antenna.
An Tom I know we get lift on 2mtrs .What about UHF?

                                                                                                Regards billko

[viking9]

Hi billko,

Yes indeed, lift applies to UHF and to SHF as well. Have a look here for the forecast ducting.

http://www.dxinfocentre.com/tropo_nwe.html

Tom

[shakysen]

Hi Tom. Thanks for the site. A very strange day Friday! on UHF. Got a problem on top band,3000ish khz.5000ish khz with QRN .Down to external psu for sbs-3.You or Mike any suggestions??

                                                                                           Billko

[Bethsalem]

Hi Stephen,

I haven't used the BSBW-1090 antenna, but I've been impressed with antennas supplied by Kinetic. I've got an SBS-3 in my study and a Beast which I use for mobile work with the whip antenna supplied with the SBS-3.

This whip antenna, mounted on a small frying pan on the inside window sill of my dining room (30 mtrs ASL), is giving me a max range of 248nm for aircraft between FL310 and FL390 today (weak to fair tropo ducting).  That's comparable to my SBS-3 with 0db gain antenna mounted on the chimney.

Tom

Thanks Tom and Billko

Am I right in thinking that the sbs-3 antenna is the AS-1105 high-gain whip?

I never thought about using a frying pan as a metal ground plane. I read elsewhere that 4 to 5 inches was the optimum size for one, but you reckon that a 10 to 12 inches metal ground plane gives better results?

I'm now stuck with a window sill and so I'm very limited on the size of an antenna setup I can place there. Also I don't want to spend a small fortune on an indoor antenna setup only to find it's only marginally better than the supplied kit. However, a cheap supermarket frying pan and a ~£25 whip antenna sounds a great setup on a budget.

Stephen

[shakysen]

Hi Stephen . Please don't take my ground plane size as the correct one. Tom did'nt suggest any size.. The measurements I got was from a Avionics site I will look in my bookmarks and post you  the site

                                                                                      Billko

[shakysen]

Hi Again Stephen. try this site http://www.cumulus-soaring.com/antennas.htm

[Smudger98]

Does a ground plane have to be flat or could it have 90o angles??

[viking9]

Does a ground plane have to be flat or could it have 90o angles??

Sorry I didn't get back earlier guys. WCR on the tele followed by the first lawn mow of the year! The minimum ground plane diameter for 1090 MHz is quite small. The one AirNav supply is around 4" diameter.  I use a frying pan as that is what I had handy for testing indoors. I used the lid of a Quality Street tin with a whip out doors for a year with good result. Cheaper than a frying pan and you can eat the contents, unless you are diabetic like me. 

[Truetrack]

Does a ground plane have to be flat or could it have 90o angles??

Only MonoPole Omnidirectional Verticals need (artifical ground plane) to function
because originally they were based on a dipole scheme with the lower element amputated
(from MF/HF towers against Ground Soil)
With VHF and higher that developed into an artificial ground pane of some sort and these
are flat horizontal whether a real metal pane of some sort or number of radials.
e.g. mobile car roof or hood, or stationary on top of mast raised into height.

To my knowledge the only exception is a shipborne VHF tilted by 45deg with only 1/2 semicircular pane
as lower half, reason they want to catch BOTH vertical AND horizontal oriented transmissions likewise.
Usually they are in pairs at opposite crosstrees.

No 90deg bends or angles.
However if you think of a large oil can cut out with a higher rim for stability
that sure would no harm - think of the raising windload on thin masts

And BTW other Ant Systems like with multiple stacked elements,
coaxial sleeve ant(dipol),
Triple leg(dipol with 60deg sloped radials) or 4 radials 45degs sloped
they all DO NOT need a Ground Plane and can be placed on-top of mast.

[Smudger98]

Thanks Klaus.. I have a square biscuit tin lid that i thought of folding into 3 to slot over a window ledge..

[viking9]

Of course a car roof makes a super ground plane but my wife won't let me have it in the dining room. 

[Smudger98]

 

[Truetrack]

Thanks Klaus.. I have a square biscuit tin lid that i thought of folding into 3 to slot over a window ledge..

Almost anything goes...
unlike the sloped radials which dims are cut to freq,
you may use any metal sheet on hand
provided you see that nothing is distorting your desired pane,
any small rim upwards is no harm , considering that 1/4 wavelength is only ~ 7cms