I’ve been using an old ham dual band mag mount as an antenna just to play around. I took some spare LMR-400 and MacGyver’ed an antenna that is doing surprisingly well! I used to have 30-40 flights on the screen at once and now I’m seeing 50-65. Just need to get it higher up.
Should have seen the wife’s face this morning when she went out to water the plants!
P.S. Ignore the whip in the background. Was trying to play on 6m during an opening a few days ago
Same for everyone here.
Mine is mounted on a second balcony. Everything is outside on a small table while the antenna is at a 6ft pole including the outdoor unit for the weather station
Every time my wife is rolling the eyes on it.
The connector / coax you’re using is likely less than great for 1090 MHz.
Calculate some attenuation for the length you used.
But if you don’t care about long range, this works 
The connector on the antenna is an N Connector. I just used what I had quickly available for a POC. Amphenol N connectors aren’t cheap. There is an N to BNC adapter and then I used an RG58 BNC to SMA that is normally delegated for running a 2m beam antenna with my HT for Summits On The Air.
Once I get plans for something more permanent the entire run will be LMR-400.
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On top, the small sliding piece of wire (with core insulation to hold the sliding wire in place) is for conveniently adjusting the length of top wire for best MESSAGE RATE (if no swr meter is available) or minimum swr if swr meter is available.
30 / 50 / 60 cm, F-female to SMA-male pigtail RG316 / RG58 / RG174
You can’t use an actual SWR meter because those require transmitting a signal on the desired frequency and measuring the amount of reflection. You can only use a passive device, such as a NanoVNA that can go above 1GHz. Set its minimum and maximum frequencies to, say, 1000 and 1300MHz. Don’t forget to calibrate it before connecting the antenna’s coax or jumper.
@abd567 I assume you’re using the center conductor of coax as the antenna wires and the coax’s dielectric as the sleeve, in which case forcing two wires into a dielectric meant for one would hold them snugly? Otherwise I’d be concerned that the trimming section may move a bit and change the SWR if the antenna gets buffeted by the wind if mounted outdoors on a roof or mast. I’d hate to have to keep lowering a mast or climbing onto the roof to retune the antenna. It may be better to just cut the 150mm wire a centimeter or two longer then cut it a bit at a time to trim the antenna for a VSWR of 1.5:1 or less, then it would be permanent. I would also spray a coat of clear acrylic or enamel onto it to prevent corrosion and keep it nice and shiny.
Doesn’t the amount of impedance vary according to the gauge of the wire? What gauge did you use?
This one is NOT meant for mounting outdoors or on a mast. I use it indoors beside a window. It may also be used in a balcony
It is made of RG6 coax. The Central whip and radials are all core wire of RG6 coax which is 18 AWG (1.024 mm dia).
You are right about trimming top wire instead of a sliding piece. However the All-Coax construction is still not suitable for outdoor use as it is mechanically weak. A better construction will be to use a N-Panel mount Connector or SO239 Connector to support V-Stub whip and Radials. These can be made of a stronger wire of say 2 or 2.5 mm dia wire instead of 1 mm dia wire of RG6 coax. Please see photo below.
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