Antenna question

Started by Pawihte in sci.electronics.basics7 years ago 55 replies

I'll be grateful if you could explain this: Is antenna gain in dB related to voltage or to power? For example, suppose there are two...

I'll be grateful if you could explain this: Is antenna gain in dB related to voltage or to power? For example, suppose there are two receiving antennas with different gains, but identical in frequency, impedance and terminating load, and antenna A has a 6dB gain over antenna B. If they are both pointed at the same transmitting source from the same distance, what will be the ratio of t...


Wide Band Antenna

Started by M. Hamed in sci.electronics.basics3 years ago 14 replies

Is there such a things as an antenna that will get me everything from HF to VHF with reasonable strength? I have a BNC telescope antenna that...

Is there such a things as an antenna that will get me everything from HF to VHF with reasonable strength? I have a BNC telescope antenna that seems to get FM broadcast and higher but very little once you start going below 100 MHz.


AM/FM tuner, cannot get AM stations?

Started by Robert Blass in sci.electronics.basics9 years ago 3 replies

I have this AM/FM tuner, bought about 10 years ago. I tried connecting an AM antenna to it. All it does is make a LOUD humming noise. Is there...

I have this AM/FM tuner, bought about 10 years ago. I tried connecting an AM antenna to it. All it does is make a LOUD humming noise. Is there some configuration I need to make the AM side of the antenna work properly? It has [3] places to put wire that attaches to your antenna. The FM antenna is just simply placing ONE wire into the hole and clamping it down. I have a few choices like ...


Antenna Lightning Protection

Started by W. eWatson in sci.electronics.basics4 years ago 18 replies

I have a mast, rotor and yagi TV antenna on my roof. The antenna is probably 15' feet above the roof. It has 12 or so large elements, and a...

I have a mast, rotor and yagi TV antenna on my roof. The antenna is probably 15' feet above the roof. It has 12 or so large elements, and a similar amount of smaller elements. There are three guy wires. It was struck by lightning about eight years ago, and took out the rotor control in the house. There was no apparent damage to the antenna it is not in use, disconnected from the TV, but ...


Yagi TV/FM Antenna--See Through Trees?

Started by W. eWatson in sci.electronics.basics7 years ago 8 replies

Is it possible for an antenna to see through a thicket of trees? I noticed a picture on a web site of a UHF antenna in an attic.

Is it possible for an antenna to see through a thicket of trees? I noticed a picture on a web site of a UHF antenna in an attic.


Replacing a headphone cord antenna with with an external one: how to do it?

Started by Tron in sci.electronics.basics11 years ago 3 replies

I have a portable radio that uses the headphone cord as the antenna. The radio's reception is very sensitive to movement of the headphone cord....

I have a portable radio that uses the headphone cord as the antenna. The radio's reception is very sensitive to movement of the headphone cord. I want to build a plug-in device so that a telescopic antenna will replace the antenna function of the headphone cord. The headphone will connect to the radio through this external device. Not being an RF person I'm not sure what kind of circuit would...


Crystal Radio Questions

Started by Joe in sci.electronics.basics8 years ago 10 replies

I'm winding a coil for a crystal radio. The original plan says to wind the antenna coil on top of the tuning coil, whereas another version...

I'm winding a coil for a crystal radio. The original plan says to wind the antenna coil on top of the tuning coil, whereas another version says to wind the antenna coil *adjacent* to the tuning coil, separated by about 1/4 inch. If I wind both versions of the antenna coil on the form, will one winding interfere with the other? That is, I would only hook up one antenna coil at a time, so ...


Re-activating a Roof-top TV Antenna

Started by Joe in sci.electronics.basics9 years ago 3 replies

I would like to help a relative "re-activate" a roof-top TV antenna on a single storey house in southern California. From the ground, it...

I would like to help a relative "re-activate" a roof-top TV antenna on a single storey house in southern California. From the ground, it looks to be physically in good shape, each of four corners has 4 guy wires holding the mast, which looks to be something close to 20 feet tall. I need a how-to to get the antenna in shape. It currently has its feed cable dangling on the mast, not...


antenna grounding

Started by Anonymous in sci.electronics.basics8 years ago 18 replies

I'm about to get of the cable tv merry go round and am installing an antenna on my roof. The problem is that the service entrance for my coax...

I'm about to get of the cable tv merry go round and am installing an antenna on my roof. The problem is that the service entrance for my coax is on the side of the house and the most direct downward line for the grounding wire ( for lightning) would be the back of the house. I need to ground both the antenna and the coax from it. Would there be any problem putting two separate ground rods i...


Generating Power through Induction with a HAM radio Antenna

Started by Aaron S in sci.electronics.basics11 years ago 2 replies

Is it possble to use an inductor with a stepdown transformer to generate power by using the power ouput of a ham radio through it's antenna? My...

Is it possble to use an inductor with a stepdown transformer to generate power by using the power ouput of a ham radio through it's antenna? My friend states his antenna is a 40Watt'er. If I can, about how much power can i expect to gather using a n inductor.


radio reception oddity

Started by RichD in sci.electronics.basics8 years ago 16 replies

I have an armband digital FM radio, for running. The earphone cord is the antenna. Reception is very sensitive to antenna...

I have an armband digital FM radio, for running. The earphone cord is the antenna. Reception is very sensitive to antenna orientation, unsurprisingly. (a problem as I circle a track) It's not the signal strength so much, but the noise level varies greatly. Anyhow, here's my question: the reception is also highly sensitive to the radio orientation, independent of the antenna. The nois...


VSWR doesn't matter? But how about "mismatch loss"?

Started by billcalley in sci.electronics.basics10 years ago 43 replies

What I gleaned from the excellent answers for the original "VSWR Doesn't Matter?" thread is that high VSWR doesn't really matter in...

What I gleaned from the excellent answers for the original "VSWR Doesn't Matter?" thread is that high VSWR doesn't really matter in a lossless transmission line environment between a transmitter's antenna tuner and the antenna, since any reflected RF energy will simply continue to "bounce" back and forth between the tuner's output impedance and the antenna's input impedance until it is, ...


300 ohm to 75 ohm impedance matching "transformer"

Started by Joe in sci.electronics.basics9 years ago 3 replies

I bought a 300 to 75 ohm "matching transformer" to hook up to a home built TV antenna. The matching transformer looks exactly like the one on...

I bought a 300 to 75 ohm "matching transformer" to hook up to a home built TV antenna. The matching transformer looks exactly like the one on this URL: http://www.solidsignal.com/prod_display.asp?PROD=WMXFMRPT I have a couple of questions: Can these matching transformers be used in either direction? That is, my antenna will get the 300 ohm end, and the TV antenna input will get the ...


Hi all...

Started by Alex in sci.electronics.basics11 years ago 3 replies

Hello lovely people, So here is what I did. I bought WinTV USB and then I have 2 Radio Shack antenna's . ONe UHF / VHF and the other a scanner...

Hello lovely people, So here is what I did. I bought WinTV USB and then I have 2 Radio Shack antenna's . ONe UHF / VHF and the other a scanner antenna plugged into WinTV box. I wish to make a RF spectrum analyser. Any code out there which would do this using the equipment I have ? Thank you. I'll keep everyone posted on what I find. Alex.


Distributed capacitance effects inductor Q?

Started by Bill Bowden in sci.electronics.basics10 years ago 3 replies

Does anyone know why the distributed winding capacitance of a loop antenna, or any inductor, degrades the efficiency? It would seem that a...

Does anyone know why the distributed winding capacitance of a loop antenna, or any inductor, degrades the efficiency? It would seem that a loop antenna with 100pF of winding capacitance in parallel with a external capacitor of 200pF would resonate at the same frequency as a antenna with no winding capacitance and a external capacitor of 300pF, and perform just as well, but apparently that'...


DAB antenna.

Started by ian field in sci.electronics.basics8 years ago 1 reply

These radios typically have a length of wire dangling out of the back for an antenna, is this just a random length of wire in the hope of...

These radios typically have a length of wire dangling out of the back for an antenna, is this just a random length of wire in the hope of catching some signal or do the manufacturers cut it to a specific tuned length? TIA.


Need circuit for antenna up from Sirius radio

Started by Anonymous in sci.electronics.basics10 years ago

I need a circuit that knows when the power is on at my Sirius Stratus radio to tell the antenna to go or stay up. Problem- my current auto radio...

I need a circuit that knows when the power is on at my Sirius Stratus radio to tell the antenna to go or stay up. Problem- my current auto radio has an aux input which I can use for my satelite radio. Great direct connection. The problem is that when I set the auto radio for aux the antenna goes down. Is there a way to sense power on the 5V input to the satilite radio and then tell the ante...


Antenna impedance

Started by riccardo manfrin in sci.electronics.basics4 years ago 19 replies

With reference to this schematic: http://www.pyroelectro.com/projects/pyro_rf_transmitter_27mhz/img/schematic.png I'd like to know if there is...

With reference to this schematic: http://www.pyroelectro.com/projects/pyro_rf_transmitter_27mhz/img/schematic.png I'd like to know if there is a general rule of thumb for determining the antenna impedance Z(w) and therefore the matching inductance L3. Also, I'd like to know what is the meaning behind the choice of the "12 inches of AWG 28" (cause 12inches do not seem to me like any fraction...


Antenna power injector and splitter

Started by Captain Dondo in sci.electronics.basics10 years ago 3 replies

I have a couple of Winegard powered antennas. The power injector has developed an intermittent failure, so I took it apart to see what...

I have a couple of Winegard powered antennas. The power injector has developed an intermittent failure, so I took it apart to see what was going on. It looks like there is an invisible break in the circuit somewhere. I could try to fix it, or I could build a new one and address some other issues. So... The injector consists of two RF jacks, one for the TV and one for the antenna. ...


long antenna

Started by RichD in sci.electronics.basics2 years ago 4 replies

During my workout yesterday, I attached a 3 meter extension to the earphone cord of my radio, as I wanted to place it at a distance. The cord...

During my workout yesterday, I attached a 3 meter extension to the earphone cord of my radio, as I wanted to place it at a distance. The cord is the antenna. I was indoors, where the reception is usually crummy. I figured the longer line should improve performance, right? No! The reception was barely decipherable. Can anyone explain the physics here? -- Rich