darklife
Modulating Madness
I just built and tested an interesting broadband antenna that works wonders for FM reception well into high VHF and some UHF bands.
Because the bowtie is a broadband antenna having an SWR as low as 1:1 over a few octaves it works wonderful for VHF and UHF applications, also using a reflector increases gain over a standard dipole.
I will have to post pictures as soon as I get a chance but I can tell you dimensions and how to build it.
The length of each bowtie element is the same as a dipole in length.
You want the length to be that of the lowest possible frequency you want to receive, or possible a little bit lower.
I shot for 80MHz causing total length to be around 6 feet for total length of both sides together.
The degree of each bowtie side should be from 60 to 90 degrees. The more the angle the larger the bandwidth.
So you can imagine in your head you have two elements that look like this..
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It has a 300 ohm impedance and is connected just like a folded dipole would be, only difference is instead of having two long identical wires much like those we use on indoor wire antennas, we have 4 wires, both sets in the shape of an extended "V".
Now either you can run the 300ohm connection points (center of the >< ) with twin lead to your stereo receiver or you can do what I did and solder a balun transformer like that used on old TV sets that convert the 300 ohm screw connectors to the 75 ohm coaxial connector. A balun will reduce gain somewhat but for reception it's not so bad, especially if your receiver only accepts that sort of input.
Forewarning this thing looks silly when put up outdoors. I'm sure most of you have seen the small 14" bowtie antennas used for DTV and UHF TV reception, well imagine the same exact thing only instead being 6 foot wide!
It is bi-directional so aim towards the stations you want just like if you used a tiny one for UHF TV reception.
The "V" angle and size isn't too important.
The longer the length of the overall antenna the lower the frequencies it will work on. I find 6 feet total covers FM reception well, VHF aircraft band, ham radio 2 meter band, VHF police bands, and even into UHF. It even works somewhat well on 400MHz+ for UHF monitoring with a scanner.
Keep in mind this is like a dipole, only instead of being a band pass type setup, it's more of a high pass setup.
Because of the broad bandwidth this thing works charms for FM. You don't have to worry about cutting a dipole to work the center of the FM band only to drop out some towards the edges, this bowtie will cover the whole band with no loss and doubles as a scanner radio antenna when you aren't listening to the FM broadcast band
Here's a description of the design..
You can use whatever type of support that will work, solid elements, wire, can use two wooden dowels to hold up ends, whatever works
Because the bowtie is a broadband antenna having an SWR as low as 1:1 over a few octaves it works wonderful for VHF and UHF applications, also using a reflector increases gain over a standard dipole.
I will have to post pictures as soon as I get a chance but I can tell you dimensions and how to build it.
The length of each bowtie element is the same as a dipole in length.
You want the length to be that of the lowest possible frequency you want to receive, or possible a little bit lower.
I shot for 80MHz causing total length to be around 6 feet for total length of both sides together.
The degree of each bowtie side should be from 60 to 90 degrees. The more the angle the larger the bandwidth.
So you can imagine in your head you have two elements that look like this..
><
It has a 300 ohm impedance and is connected just like a folded dipole would be, only difference is instead of having two long identical wires much like those we use on indoor wire antennas, we have 4 wires, both sets in the shape of an extended "V".
Now either you can run the 300ohm connection points (center of the >< ) with twin lead to your stereo receiver or you can do what I did and solder a balun transformer like that used on old TV sets that convert the 300 ohm screw connectors to the 75 ohm coaxial connector. A balun will reduce gain somewhat but for reception it's not so bad, especially if your receiver only accepts that sort of input.
Forewarning this thing looks silly when put up outdoors. I'm sure most of you have seen the small 14" bowtie antennas used for DTV and UHF TV reception, well imagine the same exact thing only instead being 6 foot wide!
It is bi-directional so aim towards the stations you want just like if you used a tiny one for UHF TV reception.
The "V" angle and size isn't too important.
The longer the length of the overall antenna the lower the frequencies it will work on. I find 6 feet total covers FM reception well, VHF aircraft band, ham radio 2 meter band, VHF police bands, and even into UHF. It even works somewhat well on 400MHz+ for UHF monitoring with a scanner.
Keep in mind this is like a dipole, only instead of being a band pass type setup, it's more of a high pass setup.
Because of the broad bandwidth this thing works charms for FM. You don't have to worry about cutting a dipole to work the center of the FM band only to drop out some towards the edges, this bowtie will cover the whole band with no loss and doubles as a scanner radio antenna when you aren't listening to the FM broadcast band
Here's a description of the design..
You can use whatever type of support that will work, solid elements, wire, can use two wooden dowels to hold up ends, whatever works
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