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Do receiver antennas need matching or not?
Hi All,
I always hear that antennas have to be matched to their radio, but in receivers (such as FM and shortwave radios) I see mostly long random length antennas used, and these antennas -- be they a telescoping whip or a long wire out a window -- are used over some really wide bandwidths. How is this possible if an impedance match must always be maintained for radios? And since there cannot be a good match over such wide bandwidths with any (typical) wire antenna, what is the downside to using these completely unmatched long antennas for receivers? (Poor gain patterns with lots of nulls? Lower sensitivity due to bad noise figure or gain match for any LNA or frontend amp? Degraded overall antenna gain)? Thanks; I'm very confused on this subject! -Bill |
Do receiver antennas need matching or not?
Bill,
That's one of those "sort of" kind of questions. It depends a lot on the particular receiver and what frequency range you plan to listen to, and then on the amount of space you have for an antenna. In general, receivers that listen to the lower frequency bands, HF for example, are more sensitive than those that are used for the higher bands (VHF, UHF, SHF). That means that to hear a typical signal a specifically designed antenna having the exact output impedance as the receiver's input impedance isn't required. Almost anything will work to some extent. The receiver just isn't that 'picky', since it typically has more 'hearing' ability than required. There's a 'catch' though. Reducing the amount of signal losses in that 'whatever' antenna is going to make the resulting signal getting to the receiver that much stronger. Something always nice to have, but there are practical limits. If that 'whatever' antenna meets your requirements, then it's as 'good' as anything, sort of. If it doesn't, then making that antenna less 'lossy' is also nice. That "less 'lossy'" thingy also includes making it directional, longer, shorter, higher, whatever, to increase the amount of signal getting to the receiver. So, looking at it from that point of view, the antenna ought'a be reasonably 'close' to what will typically 'work' well on the received frequency. Huge range in that 'close' quality and the definition of what 'works' means. There is no 'perfect', 'do everything', antenna. Just too many factors involved. 'Higher' and 'longer' tends to 'work' better than 'lower' and 'shorter', in general. Which, like any generalization, is never always true. That's the sort of 'long', half-assed, technical answer. The 'quick-n-dirty' answer is, no, they don't have to be 'matched' to the receiver. Which says nothing about transmitters. - 'Doc [all puns intended] |
Do receiver antennas need matching or not?
The difference between antennas used for receive only and antennas
used for send/receive is that in the former case you are not going to fry the radio's insides because of the mismatch. But I'll bet that as you change the settings on your antenna tuner you hear the received signal go up and down-- in particular, reception goes up as you get a better match. |
Do receiver antennas need matching or not?
"billcalley" wrote in message ... Hi All, I always hear that antennas have to be matched to their radio, but in receivers (such as FM and shortwave radios) I see mostly long random length antennas used, and these antennas -- be they a telescoping whip or a long wire out a window -- are used over some really wide bandwidths. How is this possible if an impedance match must always be maintained for radios? And since there cannot be a good match over such wide bandwidths with any (typical) wire antenna, what is the downside to using these completely unmatched long antennas for receivers? (Poor gain patterns with lots of nulls? Lower sensitivity due to bad noise figure or gain match for any LNA or frontend amp? Degraded overall antenna gain)? Correct. Those are downsides. The upside is convenience and simplicity. It's sub-optimal; but it works! |
Do receiver antennas need matching or not?
"billcalley" wrote in message ... Hi All, I always hear that antennas have to be matched to their radio, but in receivers (such as FM and shortwave radios) I see mostly long random length antennas used, and these antennas -- be they a telescoping whip or a long wire out a window -- are used over some really wide bandwidths. How is this possible if an impedance match must always be maintained for radios? And since there cannot be a good match over such wide bandwidths with any (typical) wire antenna, what is the downside to using these completely unmatched long antennas for receivers? (Poor gain patterns with lots of nulls? Lower sensitivity due to bad noise figure or gain match for any LNA or frontend amp? Degraded overall antenna gain)? Thanks; I'm very confused on this subject! -Bill The best transfer of energy is achieved when the antenna impedance matches the input circuit impedance of the receiver. This should be the case for the entire band of the desired received signal. It is not always feasible to do this and it is often not necessary. Today's receivers have very high gain and excellent selectivity. They need very small signal strengths to operate and excess signal is attenuated. So a piece of wire used as an antenna in an area where the signal strength is large will not do any worse than a perfectly matched antenna. In an area where the signal strength is weak (like Mars) matching of the antenna to the front end of the receiver is desired. There are other considerations for transmitters. Tom |
Do receiver antennas need matching or not?
billcalley wrote:
Thanks; I'm very confused on this subject! The AGC circuit in receivers has enough dynamic range to compensate for low amplitude signals from a mismatched HF antenna. The S/N ratio on HF is mostly external to the receiver. -- 73, Cecil http://www.w5dxp.com |
Do receiver antennas need matching or not?
Dear Bill (no call sign):
It depends. The goal of a receiver is to have a satisfactory signal-to-noise & distortion ratio. Many factors enter into that ratio. Let us consider just the antenna: Below something like 30 MHz, it is easy to have receivers that are quiet relative to noise picked up by most antennas. In other words, below something like 30 MHz, the SNR is determined outside of the receiver and tweaking the tuning between the antenna and receiver just increases or decreases the volume. At VHF and higher frequencies, the noisiness of the receiver tends to be a significant player. It has long been known (see MIT Radiation Lab volume 18) that the maximum SNR occurs close to a conjugate match between the antenna and receiver's first stage. However, many consumer VHF-UHF receivers (FM broadcast, TV, scanners) are presented with such large signals that there is little point in tweaking the interface between antenna and receiver for an even larger SNR. In the early days of radio astronomy, when we were still using vacuum tubes, a lot of attention was paid to having the right amount of mis-match so as to maximize SNR. So: HF and below: be concerned about the directivity of the antenna (is it reasonably sensitive in the direction of interest). VHF and above: have the antenna's impedance, transmission line's impedance, and receiver's input impedance be within a factor of 2 of each other AND point the antenna in a desired direction. Regards, Mac N8TT -- J. McLaughlin; Michigan, USA Home: "billcalley" wrote in message ... Hi All, I always hear that antennas have to be matched to their radio, but in receivers (such as FM and shortwave radios) I see mostly long random length antennas used, and these antennas -- be they a telescoping whip or a long wire out a window -- are used over some really wide bandwidths. How is this possible if an impedance match must always be maintained for radios? And since there cannot be a good match over such wide bandwidths with any (typical) wire antenna, what is the downside to using these completely unmatched long antennas for receivers? (Poor gain patterns with lots of nulls? Lower sensitivity due to bad noise figure or gain match for any LNA or frontend amp? Degraded overall antenna gain)? Thanks; I'm very confused on this subject! -Bill |
Do receiver antennas need matching or not?
On Sat, 15 Mar 2008 05:14:53 -0700, ltdoc wrote:
Bill, That's one of those "sort of" kind of questions. It depends a lot on the particular receiver and what frequency range you plan to listen to, and then on the amount of space you have for an antenna. In general, receivers that listen to the lower frequency bands, HF for example, are more sensitive than those that are used for the higher bands (VHF, UHF, SHF). More correctly, it's _easier_ to make an HF receiver with a good noise figure, and harder to do so as the frequency goes up. However, atmospheric noise goes _down_ as the frequency goes up. So for weak-signal work a receiver designer has a lot of motivation to make really quiet front ends on VHF and higher equipment. Basically if the radio is cheap (i.e. if it's for consumer use) then the front end may as well be made of wood. If the radio is used for long-distance communication (i.e. microwave links, space communication, some military or amateur radio) then designers will go to great lengths to get the noise figure down. -- snip -- -- Tim Wescott Control systems and communications consulting http://www.wescottdesign.com Need to learn how to apply control theory in your embedded system? "Applied Control Theory for Embedded Systems" by Tim Wescott Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html |
Do receiver antennas need matching or not?
On Sat, 15 Mar 2008 04:11:21 -0700, billcalley wrote:
Hi All, I always hear that antennas have to be matched to their radio, but in receivers (such as FM and shortwave radios) I see mostly long random length antennas used, and these antennas -- be they a telescoping whip or a long wire out a window -- are used over some really wide bandwidths. How is this possible if an impedance match must always be maintained for radios? And since there cannot be a good match over such wide bandwidths with any (typical) wire antenna, what is the downside to using these completely unmatched long antennas for receivers? (Poor gain patterns with lots of nulls? Lower sensitivity due to bad noise figure or gain match for any LNA or frontend amp? Degraded overall antenna gain)? Thanks; I'm very confused on this subject! -Bill In areas where it matters receive antennas are matched, and are something other than random wire. This is why you can go to Radio Shack and buy TV antennas* -- they're designed** to be both directional and a good match over the broad frequency ranges of TV signals. Get into amateur radio or military communications and you'll find many different permutations of directional, matched antennas on receive. Note: For many LNA designs, the best signal/noise ratio occurs at an impedance that is close to, but not really, a perfect conjugate match. The signal is coupled to the amplifier best at the conjugate match impedance, but sometimes the noise is enhanced even more. * or could -- does Rat Shack still carry antennas? ** kinda -- they're really designed to _look_ like they'd make a good antenna, but they're better than rabbit ears. -- Tim Wescott Control systems and communications consulting http://www.wescottdesign.com Need to learn how to apply control theory in your embedded system? "Applied Control Theory for Embedded Systems" by Tim Wescott Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html |
Do receiver antennas need matching or not?
Note: *For many LNA designs, the best signal/noise ratio occurs at an impedance that is close to, but not really, a perfect conjugate match. * The signal is coupled to the amplifier best at the conjugate match impedance, but sometimes the noise is enhanced even more. That brings up an intersting question I never did get a good answer to... It is my assertion that an LNA that is physically at room temperature (290K) can have a noise figure no better than 3 dB (i.e. its effective noise temperature is 290K) IF it is also conjugatly matched i.e. looks like 50 Ohms. Yes you can make the noise figure better than 3 dB, but then you must either cool the device or MISMATCH it to the line. In other words if it looks like 50 Ohms and it is physically at 290 K, it's effective noise temperature must also be 290K. How could it be otherwise? Comments plese. Mark |
Do receiver antennas need matching or not?
"Tom Biasi" wrote in message ... "billcalley" wrote in message ... Hi All, I always hear that antennas have to be matched to their radio, but in receivers (such as FM and shortwave radios) I see mostly long random length antennas used, and these antennas -- be they a telescoping whip or a long wire out a window -- are used over some really wide bandwidths. How is this possible if an impedance match must always be maintained for radios? And since there cannot be a good match over such wide bandwidths with any (typical) wire antenna, what is the downside to using these completely unmatched long antennas for receivers? (Poor gain patterns with lots of nulls? Lower sensitivity due to bad noise figure or gain match for any LNA or frontend amp? Degraded overall antenna gain)? Thanks; I'm very confused on this subject! -Bill The best transfer of energy is achieved when the antenna impedance matches the input circuit impedance of the receiver. OH NO! now you have done it! i hope cecil doesn't see this or you have just openend another endless energy sloshing around thread! what does happen if the antenna isn't matched to the radio? where does the mismatch energy go??? |
Do receiver antennas need matching or not?
On Sat, 15 Mar 2008 04:11:21 -0700 (PDT), billcalley
wrote: How is this possible if an impedance match must always be maintained for radios? Hi Bill, It is not always needed if the signal is strong enough. If the signal is not strong enough, then you can obtain considerable gain through tuning. Tuning also brings other advantages by rejecting signals that could depress your radio's sensitivity. 73's Richard Clark, KB7QHC |
Do receiver antennas need matching or not?
On Sat, 15 Mar 2008 16:35:00 GMT, "Dave" wrote:
The best transfer of energy is achieved when the antenna impedance matches the input circuit impedance of the receiver. OH NO! now you have done it! i hope cecil doesn't see this or you have just openend another endless energy sloshing around thread! what does happen if the antenna isn't matched to the radio? where does the mismatch energy go??? Your neighbours ;-) Less of the energy is "taken" from the received EM field. Joop |
Do receiver antennas need matching or not?
On Sat, 15 Mar 2008 09:35:22 -0500, Tim Wescott
wrote: This is why you can go to Radio Shack and buy TV antennas* -- they're designed** to be both directional and a good match over the broad frequency ranges of TV signals. I once cranked out an NEC2 model of a Radio Shock TV antenna to see what it really did over the 54-890MHz range. It was fairly horrible. There were actually a few frequencies where the impedance was close to 300 ohms. There were also a few frequencies where it actually had some gain. At some frequenies, it had more gain in the reverse direction than forward. As an example of a "directional and a good match" antenna, that typical Radio Shock TV antenna doth truly suck. I'll see if I can find the model. Unfortunately, it may have been on a hard disk that crashed a few years ago. Not having a good match between the antenna and LNA has several effects. The mismatch will affect the system noise figure thus reducing sensitivity. Some LNA's are not unconditionally stable and will oscillate when presented with a weird source impedance. At HF frequencies, the atmospheric noise level is above the receiver input noise level, so considerable mismatching can be tolerated. About about 20MHz, this is no longer the case, and a match is required. Antennas are also affected by their load impedance. A highly directional yagi antenna pattern can easily be ruined by mismatched coax or LNA input impedance. For the antenna to work as advertised, it has to see the rated load. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Do receiver antennas need matching or not?
Dave wrote:
"Where does the mismatch energy go?' It is mostly reradiated from the receiving antenna. Best regards, Richard Harrison, KB5WZI |
Do receiver antennas need matching or not?
Dave wrote:
"Tom Biasi" wrote in message ... "billcalley" wrote in message ... Hi All, I always hear that antennas have to be matched to their radio, but in receivers (such as FM and shortwave radios) I see mostly long random length antennas used, and these antennas -- be they a telescoping whip or a long wire out a window -- are used over some really wide bandwidths. How is this possible if an impedance match must always be maintained for radios? And since there cannot be a good match over such wide bandwidths with any (typical) wire antenna, what is the downside to using these completely unmatched long antennas for receivers? (Poor gain patterns with lots of nulls? Lower sensitivity due to bad noise figure or gain match for any LNA or frontend amp? Degraded overall antenna gain)? Thanks; I'm very confused on this subject! -Bill The best transfer of energy is achieved when the antenna impedance matches the input circuit impedance of the receiver. OH NO! now you have done it! i hope cecil doesn't see this or you have just openend another endless energy sloshing around thread! what does happen if the antenna isn't matched to the radio? where does the mismatch energy go??? A good deal of it is re-radiated by the antenna. Cheers, Phil Hobbs |
Do receiver antennas need matching or not?
billcalley wrote: Hi All, I always hear that antennas have to be matched to their radio, but in receivers (such as FM and shortwave radios) I see mostly long random length antennas used, and these antennas -- be they a telescoping whip or a long wire out a window -- are used over some really wide bandwidths. How is this possible if an impedance match must always be maintained for radios Andy writes: As a practical matter, if the background noise heard in the receiver increases when the antenna is attached, the antenna is good enough. This means that the atmospheric noise, in the frequency range that the receiver is tuned to, is greater than the internal receiver noise.... It also means that any signal that is to be received that exceeds the atmospheric noise, will be heard...... Unless you are using some signal processing that can detect signals below the atmospheric noise level, this is a very good rule of thumb.... Consider an airborne LORAN antenna, used on aircraft, to receive 100 khz signals. It works out that around 22 inches is the length where the atmospheric noise exceeds the general receiver noise for most receivers. Making the antenna longer will pick up more desired signal, but also more atmospheric noise, in the same ratio.....so the SNR doesn't get much better. Note that a matched antenna for 100khz will be many many hundreds of feet long.... but is never used either in boats or airplanes, since a "matched" antenna serves no advantage to sensitivity ( SNR).... These are rules of thumb, and useful approximations, but, in effect, you don't need a great antenna unless you are trying to receive a weak signal....or have a method to increase the SNR by signal processing. Andy in Eureka, Texas W4OAH |
Do receiver antennas need matching or not?
Mark wrote:
Note: For many LNA designs, the best signal/noise ratio occurs at an impedance that is close to, but not really, a perfect conjugate match. The signal is coupled to the amplifier best at the conjugate match impedance, but sometimes the noise is enhanced even more. That brings up an intersting question I never did get a good answer to... It is my assertion that an LNA that is physically at room temperature (290K) can have a noise figure no better than 3 dB (i.e. its effective noise temperature is 290K) IF it is also conjugatly matched i.e. looks like 50 Ohms. Yes you can make the noise figure better than 3 dB, but then you must either cool the device or MISMATCH it to the line. In other words if it looks like 50 Ohms and it is physically at 290 K, it's effective noise temperature must also be 290K. How could it be otherwise? Comments plese. Mark That beer in your hand was also cooled in a 300K ambient. How is that possible? (Hint: the fluctuation-dissipation theorem only applies to systems in thermodynamic equilibrium. The moment you turn on the power, that assumption is violated, just as it is in your domestic refrigerator.) An ordinary room-temperature diode has a noise temperature of 150K (Tambient/2) as you can show in about 3 lines of algebra, starting from the diode equation and the shot noise and Johnson noise formulas. Cheers, Phil Hobbs Cheers, Phil Hobbs |
Do receiver antennas need matching or not?
On Mar 15, 3:11*am, billcalley wrote:
Hi All, * *I always hear that antennas have to be matched to their radio, but in receivers (such as FM and shortwave radios) I see mostly long random length antennas used, and these antennas -- be they a telescoping whip or a long wire out a window -- are used over some really wide bandwidths. *How is this possible if an impedance match must always be maintained for radios? *And since there cannot be a good match over such wide bandwidths with any (typical) wire antenna, what is the downside to using these completely unmatched long antennas for receivers? *(Poor gain patterns with lots of nulls? *Lower sensitivity due to bad noise figure or gain match for any LNA or frontend amp? Degraded overall antenna gain)? Thanks; I'm very confused on this subject! -Bill Well, I 'm not an expert, but it seems that with a transmitting antenna, the idea is to transfer as much power as possible to increase efficiency, and so the antenna needs to be closely matched to the output of the transmitter for best results. But the receiving antenna is a different problem, since no power from the antenna is needed to drive the receiver, and so who cares about the match? The idea with the receiving antenna is to get the most voltage and highest S/N ratio with no load. The input to the receiver should be buffered with a high impedance FET amplifier, or some such, so the receiver draws almost no power from the antenna. This leaves you free to design the antenna and input tuning circuit for the highest Q and lowest noise figure without worrying about impedance match. Just my opinion. -Bill |
Do receiver antennas need matching or not?
On Sat, 15 Mar 2008 17:51:47 -0700 (PDT), AndyS
wrote: Consider an airborne LORAN antenna, used on aircraft, to receive 100 khz signals. It works out that around 22 inches is the length where the atmospheric noise exceeds the general receiver noise for most receivers. Making the antenna longer will pick up more desired signal, but also more atmospheric noise, in the same ratio.....so the SNR doesn't get much better. Agreed. However, the short 18" antenna is commonly used for handheld and aircraft Loran receivers. However marine Loran antennas are typically 8ft long. http://shakespeare-marine.com/antennas.asp?antenna=5220 That's not the only reason that Loran antennas are rather short. If the antenna were longer, the impedance would increase, causing it to pickup more percipitation static, atmospheric noise, and 60Hz harmonics. A longer antenna would also not be as narrow band and low impedance as a short (loaded) antenna. The relatively narrow bandwidth is helpful for eliminating broadcast, beacon band, and other forms of interference. Incidentally, that's also one reason why some remote Loran systems have a pre-amp that really burns some watts. It needs to handle the out of band overload and stay linear. If the antenna were made longer, the amplifier would need to handle proportionately more power (and probably melt). Some details in the patent at: http://www.google.com/patents?id=ONUrAAAAEBAJ&dq=4875019 The "background" section is worth reading. The other reason for the amplifier is to give the antenna system a 50 ohm output impedance so that cheap coax can be used. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Do receiver antennas need matching or not?
billcalley wrote:
Hi All, I always hear that antennas have to be matched to their radio, but in receivers (such as FM and shortwave radios) I see mostly long random length antennas used, and these antennas -- be they a telescoping whip or a long wire out a window -- are used over some really wide bandwidths. How is this possible if an impedance match must always be maintained for radios? And since there cannot be a good match over such wide bandwidths with any (typical) wire antenna, what is the downside to using these completely unmatched long antennas for receivers? (Poor gain patterns with lots of nulls? Lower sensitivity due to bad noise figure or gain match for any LNA or frontend amp? Degraded overall antenna gain)? Thanks; I'm very confused on this subject! -Bill Bill; I haven't looked at the back of a radio in a long time, but those that I have looked at usually had a trimmer capacitor that helped tune the antenna to the radio input. This is the impedance match you are looking at. Dave WD9BDZ |
Do receiver antennas need matching or not?
Mark wrote:
Note: For many LNA designs, the best signal/noise ratio occurs at an impedance that is close to, but not really, a perfect conjugate match. The signal is coupled to the amplifier best at the conjugate match impedance, but sometimes the noise is enhanced even more. That brings up an intersting question I never did get a good answer to... It is my assertion that an LNA that is physically at room temperature (290K) can have a noise figure no better than 3 dB (i.e. its effective noise temperature is 290K) IF it is also conjugatly matched i.e. looks like 50 Ohms. Yes you can make the noise figure better than 3 dB, but then you must either cool the device or MISMATCH it to the line. I make amplifiers with 50 Ohms input impedance and 300pV/rtHz input- referred noise. By your assertion, that should have been impossible. The trick is that the input impedance obtained by feedback: The cooled resistor trick. It works. Jeroen Belleman |
Do receiver antennas need matching or not?
On 3月15日, 下午7时11分, billcalley wrote:
Hi All, I always hear that antennas have to be matched to their radio, but in receivers (such as FM and shortwave radios) I see mostly long random length antennas used, and these antennas -- be they a telescoping whip or a long wire out a window -- are used over some really wide bandwidths. How is this possible if an impedance match must always be maintained for radios? And since there cannot be a good match over such wide bandwidths with any (typical) wire antenna, what is the downside to using these completely unmatched long antennas for receivers? (Poor gain patterns with lots of nulls? Lower sensitivity due to bad noise figure or gain match for any LNA or frontend amp? Degraded overall antenna gain)? Thanks; I'm very confused on this subject! -Bill Do you want access to China's massive pool of electronic manufacturers... but lack the time to contact suppliers, negotiate contracts, arrange shipping or monitor product quality? Don't worry - Let seriouswholesale deal with all that for you. *Check out the huge range of Gadgets, MP3 / MP4 Players, Car DVD / Audio, and Computer Accessories now by visiting the online wholesale catalog at seriouswholesale. com You'll have peace of mind thanks to the seriouswholesale Quality Control, 12-month Warranty on all products, and easy secure payment by credit card through Paypal. Selling on eBay or your own online store? Send products direct from our warehouse to your customers using our unique drop-shipping service. You can profit by selling hundreds of different products, without holding any of your own inventory! Any questions you have will be answered by the seriouswholesale English-speaking customer support team... Their aim is to make your China electronics importing business easier to run than ever before. Welcome to http://www.seriouswholesale.com. seriouswholesale - Buy from the source, profit without the hassle. - 12 Months Warranty - No minimum order restrictions - Drop-shipping with no additional fee - Pay by safely by PayPal seriouswholesale Wholesale Co., Ltd.: Chinas original and best online electronics wholesaler & drop-shipper: seriouswholesale. com |
Do receiver antennas need matching or not?
"Tim Wescott" wrote in message
... * or could -- does Rat Shack still carry antennas? Yes. If anything there's been a bit of a rebirth in antenna sales as people start hearing about free over-the-air (ATSC) HDTV. (Speaking of HDTV... Fry's is advertisiting ATSC-NTSC converters for $59, coming very close to the $49 I was predicting a while or so ago... Joerg will be pleased. :-) ) |
Do receiver antennas need matching or not?
"AndyS" wrote in message
... As a practical matter, if the background noise heard in the receiver increases when the antenna is attached, the antenna is good enough. This implies only that the antenna/receiver *matching* is good enough... yes? (I'm thinking that you would still sometimes prefer a highly directional antenna over just a dipole even though both increase the background noise. I.e., in both cases the antenna matching is good enough, but without the directionality the antenna itself might not be good enough to eliminate interference, overloading, etc. from sources other than the one you're interested in.) |
Do receiver antennas need matching or not?
On Mon, 17 Mar 2008 09:56:01 -0700 in rec.radio.amateur.antenna,
"Joel Koltner" wrote, (Speaking of HDTV... Fry's is advertisiting ATSC-NTSC converters for $59, coming very close to the $49 I was predicting a while or so ago. I saw two models at Wal-Mart for $49 each. Magnavox and some other name I don't know. That comes even closer. |
Do receiver antennas need matching or not?
David Harmon wrote:
On Mon, 17 Mar 2008 09:56:01 -0700 in rec.radio.amateur.antenna, "Joel Koltner" wrote, (Speaking of HDTV... Fry's is advertisiting ATSC-NTSC converters for $59, coming very close to the $49 I was predicting a while or so ago. I saw two models at Wal-Mart for $49 each. Magnavox and some other name I don't know. That comes even closer. Does Walmart honor the $40 coupon at: https://www.dtv2009.gov/ApplyCoupon.aspx -- 73, Cecil http://www.w5dxp.com |
Do receiver antennas need matching or not?
AI4QJ wrote:
[snip] Over the air HDTV is superior to cable and satellite HDTV. They may sell more outdoor antennas as soon as it becomes clear that, from the 1996 telecommunications, not only did the FCC ruling on small satellite dishes overrule the homeowner association covents restricting dsmall satellite antennas, they ALSO overruled covenants restricting outdoor TV (i.e.yagi type) antennas...this was done to promote fair competition for cable, satellite and broadcast TV. I did put up a regular radio shack yagi style outdoor TV antenna back then and the HOA did contact their lawyer and found they could do nothing about it. If I ever splurge and buy my 1080p, I will do it again because the OTA picture is absolutely the best. AI4QJ Put up one of these: http://www.digitalhome.ca/ota/superantenna A home brewed double Gray-Hoverman. Apparently, they work pretty well and if you build a really impressive one, the HOA will really get their panties in a bunch. -- Paul Hovnanian ------------------------------------------------------------------ The only tools one needs in life: WD-40 to make things go and duct tape to make them stop. |
Do receiver antennas need matching or not?
On Mon, 17 Mar 2008 22:13:35 -0800, "Paul Hovnanian P.E."
wrote: AI4QJ wrote: [snip] Over the air HDTV is superior to cable and satellite HDTV. They may sell more outdoor antennas as soon as it becomes clear that, from the 1996 telecommunications, not only did the FCC ruling on small satellite dishes overrule the homeowner association covents restricting dsmall satellite antennas, they ALSO overruled covenants restricting outdoor TV (i.e.yagi type) antennas...this was done to promote fair competition for cable, satellite and broadcast TV. I did put up a regular radio shack yagi style outdoor TV antenna back then and the HOA did contact their lawyer and found they could do nothing about it. If I ever splurge and buy my 1080p, I will do it again because the OTA picture is absolutely the best. AI4QJ Put up one of these: http://www.digitalhome.ca/ota/superantenna Nice. Too bad it only goes from about 400-800MHz, which covers the UHF channels. It doesn't work for the VHF channels. Looking at the 4NEC2 plots, it's not very good on VSWR, has reasonable gain, but only on the lower UHF channels (no problem because the higher channels are being auctioned off by the FCC). http://www.qsl.net/va3rr/hdtv/hoverman.htm A home brewed double Gray-Hoverman. Apparently, they work pretty well and if you build a really impressive one, the HOA will really get their panties in a bunch. The local OTA digital TV is on Channel 8 (KSBW) at roughly 87MHz. The reflector of a suitable Gray-Hoverman antenna should be about 1.5 meters wide. I think the aesthetics committee will be banging on the front door rather quickly. What's that giant fly swatter doing on the roof? I wonder if a TV antenna can legitimize a solar cell array if the array is mounted on the TV antenna? "Comparing some commercially available antennas" http://www.hdtvprimer.com/ANTENNAS/comparing.html I really like the negative gain (i.e. loss) in some of the commercial VHF antennas. Too bad they didn't run antenna patterns, as many such TV yagis have more gain in the reverse direction, than forward. Incidentally, I once built a vertically polarized omnidirectional OTA TV antenna intended as a disguise antenna (if you consider a 2.5 meter white fiberglass pipe to be suitable disguise). It worked well enough from about Channel 8 to about Channel 47. Not much gain (about 4dbi) but the big problem was that it was prone to receiving ghosts (reflections). I should probably resurrect the design, rename it "Ultimate Digital Disguise Magic Super-Antenna", and join the hype instead of fighting it. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Do receiver antennas need matching or not?
Jeff Liebermann wrote:
On Mon, 17 Mar 2008 22:13:35 -0800, "Paul Hovnanian P.E." wrote: AI4QJ wrote: [snip] Over the air HDTV is superior to cable and satellite HDTV. They may sell more outdoor antennas as soon as it becomes clear that, from the 1996 telecommunications, not only did the FCC ruling on small satellite dishes overrule the homeowner association covents restricting dsmall satellite antennas, they ALSO overruled covenants restricting outdoor TV (i.e.yagi type) antennas...this was done to promote fair competition for cable, satellite and broadcast TV. I did put up a regular radio shack yagi style outdoor TV antenna back then and the HOA did contact their lawyer and found they could do nothing about it. If I ever splurge and buy my 1080p, I will do it again because the OTA picture is absolutely the best. AI4QJ Put up one of these: http://www.digitalhome.ca/ota/superantenna Nice. Too bad it only goes from about 400-800MHz, which covers the UHF channels. It doesn't work for the VHF channels. Looking at the 4NEC2 plots, it's not very good on VSWR, has reasonable gain, but only on the lower UHF channels (no problem because the higher channels are being auctioned off by the FCC). http://www.qsl.net/va3rr/hdtv/hoverman.htm A home brewed double Gray-Hoverman. Apparently, they work pretty well and if you build a really impressive one, the HOA will really get their panties in a bunch. The local OTA digital TV is on Channel 8 (KSBW) at roughly 87MHz. The reflector of a suitable Gray-Hoverman antenna should be about 1.5 meters wide. I think the aesthetics committee will be banging on the front door rather quickly. What's that giant fly swatter doing on the roof? I wonder if a TV antenna can legitimize a solar cell array if the array is mounted on the TV antenna? Does your HOA forbid solar arrays? Some of them can be pretty anal retentive. Mine won't let me put up my thermonuclear clothes dryer. :-( "Comparing some commercially available antennas" http://www.hdtvprimer.com/ANTENNAS/comparing.html I really like the negative gain (i.e. loss) in some of the commercial VHF antennas. Too bad they didn't run antenna patterns, as many such TV yagis have more gain in the reverse direction, than forward. Incidentally, I once built a vertically polarized omnidirectional OTA TV antenna intended as a disguise antenna (if you consider a 2.5 meter white fiberglass pipe to be suitable disguise). It worked well enough from about Channel 8 to about Channel 47. Not much gain (about 4dbi) but the big problem was that it was prone to receiving ghosts (reflections). I should probably resurrect the design, rename it "Ultimate Digital Disguise Magic Super-Antenna", and join the hype instead of fighting it. Ghosts are a big problem where I live. Or multipath and the resulting dropouts the case of DTV broadcasts. That's why I like highly directional designs (both horizontally as well as vertically). Other than that, I can get all of our local stations with rabbit ears and a UHF loop. All of our DTV stations broadcast on UHF as the VHF band in the Seattle area is pretty much filled up with the legacy analog stuff. I'm not certain what the stations plan on doing once the digital cut over is complete. They might move their digital signal down onto their analog slot or abandon the analog slot altogether. That will be a factor in what kind of antenna I put up. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 -- Paul Hovnanian ----------------------------------------------------------------------- Procrastinators: The leaders for tomorrow. |
Do receiver antennas need matching or not?
Paul Hovnanian P.E. wrote:
AI4QJ wrote: [snip] Over the air HDTV is superior to cable and satellite HDTV. They may sell more outdoor antennas as soon as it becomes clear that, from the 1996 telecommunications, not only did the FCC ruling on small satellite dishes overrule the homeowner association covents restricting dsmall satellite antennas, they ALSO overruled covenants restricting outdoor TV (i.e.yagi type) antennas...this was done to promote fair competition for cable, satellite and broadcast TV. I did put up a regular radio shack yagi style outdoor TV antenna back then and the HOA did contact their lawyer and found they could do nothing about it. If I ever splurge and buy my 1080p, I will do it again because the OTA picture is absolutely the best. AI4QJ Put up one of these: http://www.digitalhome.ca/ota/superantenna A home brewed double Gray-Hoverman. Apparently, they work pretty well and if you build a really impressive one, the HOA will really get their panties in a bunch. And the best thing is that there's no size limit in the OTARD rules for these antennas. the 1 meter limit is ONLY for satellite antennas. OTA terrestrial has no size limit. Build that 20 bay curtain array. |
Do receiver antennas need matching or not?
Jeff Liebermann wrote:
On Mon, 17 Mar 2008 22:13:35 -0800, "Paul Hovnanian P.E." wrote: AI4QJ wrote: [snip] Over the air HDTV is superior to cable and satellite HDTV. They may sell more outdoor antennas as soon as it becomes clear that, from the 1996 telecommunications, not only did the FCC ruling on small satellite dishes overrule the homeowner association covents restricting dsmall satellite antennas, they ALSO overruled covenants restricting outdoor TV (i.e.yagi type) antennas...this was done to promote fair competition for cable, satellite and broadcast TV. I did put up a regular radio shack yagi style outdoor TV antenna back then and the HOA did contact their lawyer and found they could do nothing about it. If I ever splurge and buy my 1080p, I will do it again because the OTA picture is absolutely the best. AI4QJ Put up one of these: http://www.digitalhome.ca/ota/superantenna Nice. Too bad it only goes from about 400-800MHz, which covers the UHF channels. It doesn't work for the VHF channels. Looking at the 4NEC2 plots, it's not very good on VSWR, has reasonable gain, but only on the lower UHF channels (no problem because the higher channels are being auctioned off by the FCC). http://www.qsl.net/va3rr/hdtv/hoverman.htm A home brewed double Gray-Hoverman. Apparently, they work pretty well and if you build a really impressive one, the HOA will really get their panties in a bunch. The local OTA digital TV is on Channel 8 (KSBW) at roughly 87MHz. The reflector of a suitable Gray-Hoverman antenna should be about 1.5 meters wide. I think the aesthetics committee will be banging on the front door rather quickly. What's that giant fly swatter doing on the roof? The OTARD rules say, "tough beans" to the HOA. No size limit. I wonder if a TV antenna can legitimize a solar cell array if the array is mounted on the TV antenna? There are other laws in many states that prohibit a HOA from restricting alternative energy sources (like solar panels for hot water or electricity, wind generators) |
Do receiver antennas need matching or not?
In article ,
Jim Lux wrote: A home brewed double Gray-Hoverman. Apparently, they work pretty well and if you build a really impressive one, the HOA will really get their panties in a bunch. And the best thing is that there's no size limit in the OTARD rules for these antennas. the 1 meter limit is ONLY for satellite antennas. OTA terrestrial has no size limit. Build that 20 bay curtain array. There's no explicit size limit stated for the antennas. However, it could be argued that building an antenna which is larger than necessary for good reception is not protected... prohibited restrictions include those which "preclude(s) a person from receiving or transmitting an acceptable quality signal from an antenna covered under the rule." Hence, if you can receive an acceptable-quality signal on all channels with a 1-bay antenna, the FCC *might* consider as reasonable a restriction against putting up a 20-bay antenna. The rules also say "Masts higher than 12 feet above the roofline may be subject to local permitting" and that the rules do not preempt "legitimate safety restrictions". It's clear that a blanket "no on-the-roof TV antennas" restriction by HOR rules or CCRs is generally unenforceable. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
Do receiver antennas need matching or not?
On 3月15日, 下午7时11分, billcalley wrote:
Hi All, I always hear that antennas have to be matched to their radio, but in receivers (such as FM and shortwave radios) I see mostly long random length antennas used, and these antennas -- be they a telescoping whip or a long wire out a window -- are used over some really wide bandwidths. How is this possible if an impedance match must always be maintained for radios? And since there cannot be a good match over such wide bandwidths with any (typical) wire antenna, what is the downside to using these completely unmatched long antennas for receivers? (Poor gain patterns with lots of nulls? Lower sensitivity due to bad noise figure or gain match for any LNA or frontend amp? Degraded overall antenna gain)? Thanks; I'm very confused on this subject! -Bill Do you want access to China's massive pool of electronic manufacturers... but lack the time to contact suppliers, negotiate contracts, arrange shipping or monitor product quality? Don't worry - Let seriouswholesale deal with all that for you. *Check out the huge range of Gadgets, MP3 / MP4 Players, Car DVD / Audio, and Computer Accessories now by visiting the online wholesale catalog at seriouswholesale. com You'll have peace of mind thanks to the seriouswholesale Quality Control, 12-month Warranty on all products, and easy secure payment by credit card through Paypal. Selling on eBay or your own online store? Send products direct from our warehouse to your customers using our unique drop-shipping service. You can profit by selling hundreds of different products, without holding any of your own inventory! Any questions you have will be answered by the seriouswholesale English-speaking customer support team... Their aim is to make your China electronics importing business easier to run than ever before. Welcome to http://www.seriouswholesale.com. seriouswholesale - Buy from the source, profit without the hassle. - 12 Months Warranty - No minimum order restrictions - Drop-shipping with no additional fee - Pay by safely by PayPal seriouswholesale Wholesale Co., Ltd.: Chinas original and best online electronics wholesaler & drop-shipper: seriouswholesale. com |
Do receiver antennas need matching or not?
On 3月15日, 下午7时11分, billcalley wrote:
Hi All, I always hear that antennas have to be matched to their radio, but in receivers (such as FM and shortwave radios) I see mostly long random length antennas used, and these antennas -- be they a telescoping whip or a long wire out a window -- are used over some really wide bandwidths. How is this possible if an impedance match must always be maintained for radios? And since there cannot be a good match over such wide bandwidths with any (typical) wire antenna, what is the downside to using these completely unmatched long antennas for receivers? (Poor gain patterns with lots of nulls? Lower sensitivity due to bad noise figure or gain match for any LNA or frontend amp? Degraded overall antenna gain)? Thanks; I'm very confused on this subject! -Bill Do you want access to China's massive pool of electronic manufacturers... but lack the time to contact suppliers, negotiate contracts, arrange shipping or monitor product quality? Don't worry - Let seriouswholesale deal with all that for you. *Check out the huge range of Gadgets, MP3 / MP4 Players, Car DVD / Audio, and Computer Accessories now by visiting the online wholesale catalog at seriouswholesale. com You'll have peace of mind thanks to the seriouswholesale Quality Control, 12-month Warranty on all products, and easy secure payment by credit card through Paypal. Selling on eBay or your own online store? Send products direct from our warehouse to your customers using our unique drop-shipping service. You can profit by selling hundreds of different products, without holding any of your own inventory! Any questions you have will be answered by the seriouswholesale English-speaking customer support team... Their aim is to make your China electronics importing business easier to run than ever before. Welcome to http://www.seriouswholesale.com. seriouswholesale - Buy from the source, profit without the hassle. - 12 Months Warranty - No minimum order restrictions - Drop-shipping with no additional fee - Pay by safely by PayPal seriouswholesale Wholesale Co., Ltd.: Chinas original and best online electronics wholesaler & drop-shipper: seriouswholesale. com |
Do receiver antennas need matching or not?
Dave Platt wrote:
In article , Jim Lux wrote: A home brewed double Gray-Hoverman. Apparently, they work pretty well and if you build a really impressive one, the HOA will really get their panties in a bunch. And the best thing is that there's no size limit in the OTARD rules for these antennas. the 1 meter limit is ONLY for satellite antennas. OTA terrestrial has no size limit. Build that 20 bay curtain array. There's no explicit size limit stated for the antennas. However, it could be argued that building an antenna which is larger than necessary for good reception is not protected... prohibited restrictions include those which "preclude(s) a person from receiving or transmitting an acceptable quality signal from an antenna covered under the rule." Hence, if you can receive an acceptable-quality signal on all channels with a 1-bay antenna, the FCC *might* consider as reasonable a restriction against putting up a 20-bay antenna. And the FCC has carefully stayed away from defining "acceptable" . In fact, in one case, they've said that it's in the judgement of the person receiving the signal (The HOA wanted to make the homeowner put the antenna inside the attic, claiming that since they were close to the transmitter site, that an acceptable signal was available). (I can't find the reference off hand.. it's in Maryland or Virginia, as I recall) One might also want to look up the very interesting case of Stanley and Vera Holliday (5 masts, 30 ft high, 3 dishes, etc.) http://www.fcc.gov/Bureaus/Cable/Ord...9/da992132.txt I spent a while trying to hunt down what "acceptable" might be in FCC rules terms (e.g. what's a minimum performance standard for a Cable TV).. It's pretty tough to find a numerical standard. There are standard service contours which relate to RF field strength, but they're also statistical. For digital receivers, in fact, on 21 Jan 2001, the FCC: "Denied requests to set performance standards for digital receivers, expressing concern that the effect of setting such standards at this point would be to stifle innovation and limit performance to current capabilities. The Commission said it would continue to monitor receiver issues;" As recently as June, 2007, an article in CED Magazine said:"The FCC has never before adopted receiver performance specifications or interference rejection requirements. It has the authority to do since Senator Goldwater introduced a bill that became Public Law 97-259 in 1982, which added the italicized language below to the Communications Act:..." ATSC has a document A/74 which defines a recommended practice for receiver performance, but it's kind of a clunky document, based on technology that was available in 2003-2004, and not really intended for this sort of thing. FWIW, the FCC assumes you need 7dB SNR for UHF and 10dB for VHF, with an assumed 7dB NF. So, one could claim you need that 20x20 bay antenna to get enough signal to compensate for your horrid transmission line and terrible receiver. The rules also say "Masts higher than 12 feet above the roofline may be subject to local permitting" and that the rules do not preempt "legitimate safety restrictions". The FCC has set a pretty high bar on safety restrictions. They have to be clearly articulated and justified in the rules (i.e. no "in the opinion of the architectural review board, that's unsafe"). The 12 foot thing is a building code issue. The city or jurisdiction would have to have a fairly specifically articulated justification. It's clear that a blanket "no on-the-roof TV antennas" restriction by HOR rules or CCRs is generally unenforceable. Yep.. In fact, can't even have a "must put antenna in position X" or "must plant or paint" rule, unless the cost of compliance is trivially small (as in $5, see the Meade,KS case) and has ZERO effect on reception |
Do receiver antennas need matching or not?
On Tue, 18 Mar 2008 10:54:25 -0700, "Paul Hovnanian P.E."
wrote: Does your HOA forbid solar arrays? Some of them can be pretty anal retentive. Mine won't let me put up my thermonuclear clothes dryer. :-( No home owners association in my neighborhood. (However, I am the self-appointed chair person and bill collector for the private road committee). If we had an HOA, I would be the first to be lynched as I have 2 dead cars in front of the house, a huge mess ready for recycling, and an antenna farm on the roof. However, I have friends that bought into the "planned community" philosophy and are stuck with CC&R's from hell. Basically, anything that can be seen from ground level is unacceptable. In the CC&R's I've read, solar arrays are certainly not allowed, especially on the roof. http://www.renewableenergyworld.com/rea/news/ate/story?id=45648 I've found the local cities and county bureaucracy on behalf of various homeowners. Batting average is about 50%. Ghosts are a big problem where I live. Or multipath and the resulting dropouts the case of DTV broadcasts. That's why I like highly directional designs (both horizontally as well as vertically). Other than that, I can get all of our local stations with rabbit ears and a UHF loop. I live too far away from the local digital TV xmitters to get reliable reception. My rule of thumb is that if OTA analog TV reception is marginal, digital TV will be worse. Highly directional antennas are the right way to eliminate ghosts (reflections). However, I keep running into problems with f/b (front to back) ratio problems, where the ghosts are reflected from behind the antenna. That's where the lower gain, but higher f/b ratio antennas, such as a barbeque grill backed bowtie array, makes more sense. My preference is to use single channel narrowband yagi's for maximum gain, but that gets really ugly as one per channel is required. All of our DTV stations broadcast on UHF as the VHF band in the Seattle area is pretty much filled up with the legacy analog stuff. We have Channel's digital 10 (KSBW) and digital Channel 12 (KNTV) http://en.wikipedia.org/wiki/KNTV http://en.wikipedia.org/wiki/KSBW I once did a paper design for a trapped yagi, designed solely for channels 8 and 11 (the analog channels) and no others. It probably would work, but nobody was interested in buying one. I'm not certain what the stations plan on doing once the digital cut over is complete. All of them. The station owners would need to be insane not do do digital. It's a free extra channel with the oportunity to sell additional services (i.e. data broadcasting). They might move their digital signal down onto their analog slot or abandon the analog slot altogether. That will be a factor in what kind of antenna I put up. Duh... I never thought to ask the local broadcast engineers what the channel lineup is going to be after the Feb 17, 2009 fire drill. I'll ask. Every day, I go on an extended exercise constitutional. One day, I decided to count outdoor TV antennas in my mountain neighborhood. My guess is that I passed about 100 houses and only saw three outdoor antennas (which looked ancient and inoperative). I'm wondering if anyone watches OTA TV in my area. -- # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060 # 831-336-2558 # http://802.11junk.com # http://www.LearnByDestroying.com AE6KS |
Do receiver antennas need matching or not?
On Tue, 18 Mar 2008 16:25:02 -0700, Jeff Liebermann
wrote: On Tue, 18 Mar 2008 10:54:25 -0700, "Paul Hovnanian P.E." wrote: [snip] However, I have friends that bought into the "planned community" philosophy and are stuck with CC&R's from hell. Basically, anything that can be seen from ground level is unacceptable. In the CC&R's I've read, solar arrays are certainly not allowed, especially on the roof. http://www.renewableenergyworld.com/rea/news/ate/story?id=45648 I've found the local cities and county bureaucracy on behalf of various homeowners. Batting average is about 50%. [snip] Check your state laws, solar is allowed, period, here in AZ... irrespective of HOA regulations. ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | America: Land of the Free, Because of the Brave |
Do receiver antennas need matching or not?
On Tue, 18 Mar 2008 17:06:21 -0700, Jim Thompson
wrote: On Tue, 18 Mar 2008 16:25:02 -0700, Jeff Liebermann wrote: On Tue, 18 Mar 2008 10:54:25 -0700, "Paul Hovnanian P.E." wrote: [snip] However, I have friends that bought into the "planned community" philosophy and are stuck with CC&R's from hell. Basically, anything that can be seen from ground level is unacceptable. In the CC&R's I've read, solar arrays are certainly not allowed, especially on the roof. http://www.renewableenergyworld.com/rea/news/ate/story?id=45648 I've found the local cities and county bureaucracy on behalf of various homeowners. Batting average is about 50%. [snip] Check your state laws, solar is allowed, period, here in AZ... irrespective of HOA regulations. ...Jim Thompson The State of Schwarzenegger has had a "Solar Right Act" since 1978. See: http://www.sandiego.edu/epic/publications/documents/070123_RightsActPaperFINAL.pdf The Calif Civil Code Section 714 limits the power of HOA's and governments to restrict solar installations. http://www.akeena.net/cm/About_Solar_Power/California_Civil_Code_714.html The problem is that term there seems to be some variations in what constitutes "reasonable restrictions" which are allowed by the law. If the purpose of the CC&R's is to maintain some semblance of aesthetic integrity, the local courts have ruled it "reasonable" for them to block the installation of just about anything with a visual impact. The interpretation of "reasonable" varies in different jurisdictions but locally, it seems almost random. Incidentally, I've read CC&R's that were apparently written perhaps 50 years ago. They're full of restrictions based on race, color, ethnicity, and such, which are obviously unenforceable. The buyers were told that that the old contract is good enough because anything that's illegal won't be enforced. These contracts tend to also have very broad clauses blocking "anything with an aesthetic impact" and such, which is where the solar prohibition originated. One contract I've read itemized examples of prohibited installations, which included all forms of antennas and mentioned solar panels. Locally, one planning department imposed some siting and support structure restrictions that effectively prevented installing of any solar panels. That apparently was accidental, but it took a year and an expensive legal action to get them to admit that they goofed. One homeowner wanted a variance to install the solar panels very close to the property line. No CC&R's. The variance was denied because of neighbors protests. It went to court and he lost. Another tried to get his radio tower approved on the basis of it providing supports for his tower mounted solar panels. That also was denied. -- # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060 # 831-336-2558 # http://802.11junk.com # http://www.LearnByDestroying.com AE6KS |
Do receiver antennas need matching or not?
On Mon, 17 Mar 2008 18:51:33 GMT in rec.radio.amateur.antenna, Cecil
Moore wrote, Does Walmart honor the $40 coupon Duh. |
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