Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g. TV or radio) waves. -Wikipedia
4
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0answers
39 views
What, if anything, makes shielded loop antennas so great at rejecting local noise?
There is a folk wisdom, among amateur radio operators, that if you have a lot of noise on HF, such as in an urban location, then using a shielded magnetic loop antenna for receiving is really great ...
-5
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0answers
27 views
Given desired gain, compute the number of slot radiators [closed]
Any idea?
they form an antenna array.
I can calculate the effective area out.
But then?
Thanks!
1
vote
0answers
52 views
Does skin effect distort a transmission pattern?
This question got me thinking. Homebrew ham-radio antenna is typically a monoband contraptions; perhaps SWG 16 through 21. Thinner wire is more resistive, but at HF/VHF skin effect comes into play ...
1
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0answers
56 views
Waves and Antenns
What is meant when someone says that a wave is linear and reciprocal, and also what is meant by antennas are linear, bilateral and passive
9
votes
4answers
186 views
Why can a feedline be cut randomly when the antenna needs a specific length?
With a mobile two-way radio you have the radio, an antenna mount kit and the actual whip antenna.
The antenna needs to be trimed to the correct length so to match the freequency you are Tx/Rx on.
...
-2
votes
0answers
38 views
Why would a 3G repeater stop working? [closed]
I recently purchased a 3G repeater identical to this one, for my dad's boss who moved into an area with horrible connectivity (both mobile and wired). The first few months the signal went from 1 or 2 ...
2
votes
1answer
55 views
Detached antenna and connecting wire length
Since my this particular question didn't get any answer, I thought of asking a more focused question, along a path which seems a bit more feasible after few tests.
Is it possible to install the ...
0
votes
1answer
74 views
Antenna signal through category 5 cable
Can an antenna signal (from an antenna cable) be transfered along with an ethernet signal through a category 5 cable? Will I lose too much signal quality?
Antenna specification:
...
2
votes
1answer
141 views
Can enough RF power melt an antenna?
I've heard of someone getting RF burns by touching a high power antenna. If enough power is supplied to the antenna could it melt, or would anything else happen? If so, how much power would have to be ...
2
votes
0answers
63 views
Wireless water level sensor, in sump. Installation best-practices for longivity
My wireless water-level sensor is working fine, and when deployed in the sump-well, it is giving me periodic readings quite well. At this stage, I have the circuit still on a breadboard, and now plan ...
0
votes
0answers
46 views
Embedded project using Mux and Demux for antenna
In our current embedded project we are implementing a GPS ,GSM and Wifi Module. To connect these modules to external antenna board,separate SMA cables are used.As our design requires each of the ...
1
vote
2answers
71 views
Embedded system with SMA connectors
I am developing an embedded system that performs GPS and Wifi operation with separate modules for each and two SMA connectors to connect the respective antennas. Once it is being installed, is there a ...
1
vote
2answers
71 views
Source of electromagnetic signal in kHz regime
I was wondering what emits electromagnetic signals in the kHz regime? When I touch the inner pin of an BNC cable connected to an oscilloscope, I see a large sinusoidal signal with ca 40 kHz.
0
votes
1answer
61 views
Repair a xbee wire antenna?
last year I bought a xbee pro s2b, the wire antenna one. After some use, the antenna started to loose, and last week it just broke. Is there a way to repair it? I soldered it again, and it holded some ...
0
votes
1answer
37 views
antenna multicoupling connecting lines
I'm trying to find information about how to properly calculate the connecting coax length in a string of cavity filters for a VHF multicoupler. I figure it should be something like a 1/4 wave length ...
1
vote
0answers
43 views
Antenna Identification
I believe the right most antenna is a mono-pole helical "rubber ducky" (please correct if wrong).
But what type of antenna is on the left? It is terminated with a U.FL connector (not shown) and the ...
-1
votes
1answer
102 views
Question about transmitter/reciever
I have built a transmitter/receiver with an antenna and crystal. I am wondering if it is stable.
Here is my transmitter:
simulate this circuit – Schematic created using CircuitLab
Here ...
-4
votes
2answers
183 views
How to make a Transmitter/Receiver [closed]
I am trying to make a transmitter and a receiver, I have two crystals and two antennas (basically a straight piece of metal with plastic covering), how could I make a transmitter and receiver with ...
3
votes
3answers
202 views
RF Design: A Bluetooth Repeater
I am currently stumped in the design process in creating a method to intercept Bluetooth signals with an antenna and simply outputting the exact signal through another antenna.
Some Background
I ...
1
vote
2answers
93 views
Dipole antenna length calculation — why so much variation?
Was checking few online calculators for dipole antenna length computation, and found that each tool, gave a different length. Is dipole construction based purely on heuristics, or is there some sound ...
1
vote
1answer
87 views
WiFi antenna 1T1R mode
I have a question related to 802.11n wi-fi antenna. What actually do we mean by 1T1R mode for Wi-Fi?
As per wiki, the same channel is used for Tx & Rx:
http://en.wikipedia.org/wiki/MIMO
...
1
vote
2answers
147 views
Chip antenna mounting considerations
I'm using this chip antenna with a 868MHz radio (RFM12B): http://www.johansontechnology.com/datasheets/antennas/0868AT43A0020.pdf
According to the datasheet's mounting considerations there's a trace ...
0
votes
0answers
85 views
How can I add an external antenna to a VHF HT with no external connector? [closed]
I have a marine vhf radio I use for kayaking (http://www.midlandradio.com/Marine-Radio.O01/Nautico-1) I has no external antenna connector.
When at home I want to improve reception (not ilegal where I ...
-2
votes
1answer
66 views
How to use ANT-433-SP antenna?
Could someone please explain to me how to use this antenna?
http://www.linxtechnologies.com/resources/data-guides/ant-433-sp.pdf
The picture on the last page called "Recommended Mounting" is really ...
3
votes
1answer
185 views
Need help with selecting an antenna for PCB
I have designed a pair of circuits which utilize the QAM-TX2-433-ND/QAM-RX2-433-ND transmitter/receiver.
So far everything is hooked up on solderless breadboards, with just a length of wire for ...
0
votes
1answer
65 views
Using chip antennas over a 50 foot distance
I want to build a coin sized receiver that can operate over a distance of 50 feet. I am interested in using a 2.4 GHz ceramic chip SMD antenna, like the one described here
...
2
votes
1answer
181 views
WiFi antenna's shield
Newbie question:
I've an Android TV stick (Rikomagic MK802 III) and I'm having wifi signal problems. I've opened the device, and this is what I've found:
Both the wire and the shield are connected ...
1
vote
1answer
130 views
Antenna input power
I have internet dongle huawei e3131. It has external antenna connector. I made at home some type of parabolic antenna. Picture for illustrative purposes (without foil) :)
Basically it put foil ...
0
votes
2answers
403 views
How to design Yagi-Uda Antenna? [closed]
I would like to know the theory concept behind how to design the Yagi-Uda Antenna. And how it works? Can anybody give the ideas and suggestions?
0
votes
2answers
153 views
Antenna analyzer
I want to measure the impedance of an antenna (at 434MHz) and for learning/fun try to build a circuit to do so.
I found the return loss bridge
http://www.vk2zay.net/article/179
Can I measure a ...
1
vote
1answer
91 views
Connecting horn antenna to a gunn transceiver
I have a surplus Microsemi MO9072 24GHz gunn transceiver (Datasheet) and a matching MDT86552 horn antenna (Datasheet) that I'd like to use in a project. In the same package was a waveguide of some ...
1
vote
1answer
109 views
GPS module antenna shielding
I am designing a PCB including a GPS module. I am using the Locosys LS20031 which has a antenna mounted on it. The module is mounted on the board with 1" plastic studs and a connector connects it to ...
-3
votes
1answer
106 views
What is this connection socket called? [closed]
I have a Pogo Alert+ GPS system. It has a port on the rear for an external GPS antenna. What is the port called so I can research antennas with the correct connection cable?
1
vote
1answer
151 views
Small high gain directional antenna
I want to build a high gain directional antenna for the 915MHz frequency band.
I have been looking into waveguide and yagi antennas, which seems to fulfill my gain a directional requirements but ...
14
votes
6answers
572 views
Why is an inductor not a good antenna?
[An antenna must have] current flowing along its length, so that the resulting fields radiate that energy into space. (Receiving antennas are just this process in reverse).
[This] explains why ...
2
votes
1answer
144 views
Why can a UHF RFID antenna read a LF tag?
How can a RFID UHF (Ultra High Frequency) antenna read a LF (Low Frequency) tag?
I have a antenna designed for UHF made in China, but it can read every tag I have tried (UHF, LF, HF), I don't know ...
0
votes
2answers
111 views
What are the components needed for this receiver?
I want to build a simple crystal radio receiver. I do not want amplify the signal received. I want to detect the presence of a transmitted signal, and then use the presence of the received signal as a ...
0
votes
2answers
84 views
Can I turn a device on and off using an antenna and tuner? Do I need to amply the signal?
I would like to use a radio receiver to turn a device on and off. The idea is that when the signal is received, the device is turned on, and when the signal stops, the device turns off. I want to use ...
0
votes
1answer
317 views
Boosting wifi antenna with aluminum foil: ideal placement/size?
On more than one occasion I have successfully (and significantly) improved the wifi signal a desktop computer was getting simply by taking a flat sheet of aluminum foil and curving it into a ...
5
votes
3answers
190 views
What specific parts of a radio receiver use power? Does receiving the signal need the battery
Does a radio receiver need power from a battery in order to receive a signal, or is the power just used to amplify the signal? If you wanted to simply detect a radio signal of a certain frequency (not ...
3
votes
1answer
137 views
RFID coil - ends broke, can I resolder?
The 125kHz RFID scanner / reader device I have, has a coil like this:
NB> Don't have a good camera handy at the moment, so had to share a cropped image from Alibaba, but the pic is very close to ...
4
votes
2answers
186 views
Chip antenna layout
I am trying to integrate a chip antenna but I'm unable to understand the layout guidelines in the application note.
Can any RF experts comment on what this actually means for the PCB layout - is the ...
3
votes
1answer
152 views
How does the addition of a bias-t circuit affect the impedance of a transmission line?
I've got a GPS circuit where the antenna is connected directly to the GPS receiver via a coplanar waveguide designed for an impedance of 50ohms. Unfortunately, I neglected to add the bias-t circuit ...
1
vote
1answer
81 views
Antenna Array Solid Angle
I am currently trying to design, in theory, a large wireless power spot beaming antenna for a satellite to transfer 200 MW at a wavelength of 116 mm. I was wondering how I could design it so that a ...
3
votes
2answers
362 views
adding a yagi antenna to a bluetooth dongle
I want to set up a Bluetooth link between devices that are over 2000 feet apart. Yagi antennas for 2.4GHz that can connect to routers are available. A cheap Bluetooth dongle that can be easily taken ...
1
vote
3answers
117 views
Trying to understand range and frequency of an RFID reader
I am trying to understand how range of communication between RFID reader and tag is related to frequency and power.
1- So if I increase frequency, the range will be shorter or larger? why? (I need ...
7
votes
2answers
303 views
What do I need in order to build and test a ferrite rod antenna for a specific frequency?
I am trying to piece together what I'd need for a small hobby project. I'd like to build something that is basically the equivalent to a home made avalanche beacon finder. Avalanche beacons transmit ...
1
vote
2answers
88 views
Using a WiFi antenna for UMTS
I'm thinking of increasing my 3G USB modem's signal reception using an antenna. I know a UMTS(2.1 GHz) antenna is recommended.
I need to know whether a WiFi (2.4 GHz) antenna will do the job (as I ...
0
votes
0answers
83 views
Connecting IP microwave radio link directly to SerDes
Is it possible to connect RF front end (low noise block) circuit of microwave/radio antenna directly to SerDes (serial transcivers like RocketIO in Xilinx)?
I am asking since SerDes has a Data Clock ...
3
votes
2answers
280 views
Does Wifi signal strength affect link speed?
If Windows says my signal strength is poor, is my bit-rate lower than if Windows says the signal strength is excellent? I have poor signal strength and I have:
1) raised my access point to clear ...
