simple information about bowtie antenna

[david21]

bowtie antenna dimensions

i'm going to design a planar bowtie antenna consisting two triangle metal plane such as bowtie. but i don't have enough information about them can anybody guide me and answer these questions:

1-what is the advantages of bowtie antenna?
2-in which frequencies is it used?
3-how should feed it?
4-whats the design formulas for bowtie antenna(for example relationship between antenna dimention and angle with frequency)?
5-is it a wideband antenna or not?

regard><

 

[unkarc]

bowtie antenna gain

Hi,

I found the followings on your questions:

1) "Bowtie

The bowtie antenna is known for its simplicity and ist broadband performance. It is a wire approximation to the solid biconical antenna. They are commonly used for UHF television antennas where several elements may be arrayed and placed in front of a flat screen reflector. The bowtie antenna by itself has a broad pattern with low gain similar to the pattern of a dipole. For the television antenna the gain is increased by arraying several elements together and adding the reflecting screen. "

2) It is answered above

3) It needs a BALANCED transmission line or a coax cable with a BALUN just like a normal dipole

4) Basically Karl Rothammel : AntennenBuch and ARRL AntennaBook include formulas to start with, and see some hint at http://www.cebik.com/mu/mu6a.html
or see also **broken link removed**
The above books can be reached in any library through their interlibrary service.

5) Yes, wideband, see above 1)

rgds
unkarc

 

[david21]

bowtie formula =

Dear unkarc,

thx verymuch. by the way i want to know if there is some simple formulas or relationship between bowtie antenna parameters, such as bowtie angle, arms length and frequency.

i mean is there any simple formula for designing a new bowtie antenna in a special frequency band such as:

Gain=Ψ(θ,f,L) ..... or ..... Bandwidth=Ψ(θ,f,L) ..... or ..... etc

where

θ is the angle of bowtie plane
f is frequency
L is arms length.

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/regard\

 

[flatulent]

bowtie antenna reflector

This is a two dimensional approximation to the three dimensional case of two cones fed at their apex. The frequency range is from a quarter wavelength per half to infinity. There are practical problems as the frequency is increased as the radiation pattern breaks up into many lobes with nulls between. For the cone case, the impedance lowers as the cone angle increases.

 

[unkarc]

70cm bowtie

Hi David21,

You can find some data/hints on dimensions at link:

**broken link removed** and see mainly the fifth link there on broad-band half wave dipoles. In the text you can find explanations.

I found Rothammel's Antennenbuch online!!! but it is in Hungarian translation (the original book is in German of course). Nevertheless it should be useful to you because of the Figures. See this link to the book:

**broken link removed** and go down to page 328 and 329:

**broken link removed**
**broken link removed**

In Fig 26.1 the length l is in wavelength (I mean l~0.7...0.8; points x x are the feed points)

In Fig 26.2 the vertical axis is the input impedance in Ohms

In Fig 26.3 the verical axis is the antenna gain, the horizontal axis is the frequency.


I did not find such a detailed dimensions for this antenna elsewhere, sorry.

rgds
unkarc

 

[heedavid]

antenne rothammel

Dear david21,

Let's see if I can answer your queries, based upon my limited experience with bowties...

1-what is the advantages of bowtie antenna?

Bowtie antenna is a balanced antenna, which means you will expect low cross-polarisations. It is broader in bandwidth when compared to the normal wire dipole, which can be led further if you plan to make a broadband array.

2-in which frequencies is it used?

Oh! It can be used at any frequency! Just ensure that the side of the bowtie-triangle is a quarter-wavelength to the lowest frequency of interest. So technically, quarter-wave plus quarter-wave will make it a half-wave-length dipole!

3-how should feed it?

Like some forum-threadders say, you can feed it with coaxial lines (but this time round you gotta find out what is the optimal height your radiators should be to the ground plane), or you can feed it via microstrip transmission lines.

4-whats the design formulas for bowtie antenna(for example relationship between antenna dimention and angle with frequency)?

I think I just casually mentioned about the dimension criteria as above. As for the flare angle, the basic knowledge goes that the broader the angle, the broader the bandwidth. 60 to 90 degrees are good try-outs!

5-is it a wideband antenna or not?

Contrary to what most people would say, I prefer to call it BROADBAND. Anything which has a frequency response match of less than an octave (obviously must be more than just a few percent, e.g. 5%), is broadband. Anything more, is wideband. This is just my technical preference. It helps to not mislead people.

Hope these helps.

BR,
Dave

 

[aniakhan]

Re: antenne rothammel

hi,
can you tell me what dose it mean while you say in your reply"Just ensure that the side of the bowtie-triangle is a quarter-wavelength to the lowest frequency of interest. So technically, quarter-wave plus quarter-wave will make it a half-wave-length dipole"please if any one can explain this line to me