Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
have a look @ the antennas here. go to projects, and then to antennas. i'm not sure if these antennas are suited for those kind of frequencies, but have a look neway. :lol:
no friend
this is not i want i am looking for i need small siza antenna and it will be great if its cricuit or easy to design antenna i just want to cover small area like 100 Maters but in 700Mhz to 1000Mhz so help :arrow:
Mouser has an antenna for 900/1800 mHz for $7.65. It is 12 mm long and surface mount. You can connect it direct to the transmitter output for maximim efficiency. I used the 433 mHz antenna, it worked well. Mouser part number: 240-4313-118-00918
A quarterwave whip is one quarter of a wavelength long, you should trim it accurately using an SWR meter - although you could be struggling at the frequencies in question?.
The frequencyt range you indicate is very broad. Sometimes in these cases a discone antenna works - just search on 'discone' or discone antenna' and you'll see what I am describing.
If you intend to operate at a fixed frequency then there are more choices. Amateur radio handbooks contain a lot of information on the subject.
The antenna is only one part of it - the feedline or that which connects the antenna to the transmitter or receiver, can be critical if distance between the antenna and equipment is more than a few feet. One issue is the attenuation or loss of signal. Belden makes many types of coaxial cables. Take a look at their website for more information. A commonly used line for UHF work is Belden 9913. Compare the performance of that at 1,000 mHz to something like RG-58 and you'll see what I mean.
There are plenty of ideas and suggestions above, but any antenna covering a wide range isn't going to be a very effective one - which is why cell phones are high power and short range!.
Any conductor can be used as an antenna and will radiate or capture some RF. As with many other situations in life there are times when a less than ideal design is used because many other factors have to be addressed. The cell phone antenna is one of those situations. It is likely that the antenna is simply the way it is because it can't be any bigger. It may be far from a good antenna at these frequencies but as I said above, any conductor will radiate RF. The cell phone itself has the circuitry to deal with this shortcoming. As Nigel said - they make up for the shortfalls with more power or increased receiver sensitivity. It also has circuitry to protect the transmitter from the gross mismatch and the changing mismatch that is the result of changes in position, proximity to other things, etc. None of that makes the antenna better - electrically the antenna might be a poor design but it's the best that can be done under those circumstances.
I just got book from a friend about hardware hacking projects
(like hacking Furby and many more). one of the projects was
antena to extend range of the wireless card used in PC.
autor was ilustrationg removal of the standard antena and replacing
it with ca 1" long wire inside the tin can. to attach it to computer
he used short coax cable. this boosted range 10-16 times.
can was ca 3" diameter and 4" high and accordign to article bigger can
is better.
to make it even bigger range, he used pair of satelite dishes to
focus the signal. it supposedly worked for distance like 10-16miles
without any amplifier circuits etc. - just the mentioned hardware.
are you willing to experiement?
I will try to help you out, if you can tell me:
1. Why do you need the frequency range of 700 mHz to 1000 mHz?
2. How much power is to be radiated? What is your transmitter?
3. How far will the antenna be from the transmitter?
4. Do you want to transmit in all directions, or one direction?
I just rec'd my Ramsey catalog and found several log-periodic yagis for UHF frequencies - essentially etched on PCB material. You might take a look at the Ramsey website for more information.
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