edit: mod delete, answered own question

I appreciate it, that Comet looks intriguing, especially when I found a picture of it twisted back onto itelf in a loop without a breakage! Pretty cheap too, enough to grab and test and not worry if theyres little improvement.

Very cool! Anything space/rockets/nasa related always blew my mind as a kid, to be able to interact on any scale with something in that realm was always a childhood goal! Kinda sparkin old childhood dreams... but if a hobby like ham can keep holding your interest with new avenues and goals to achieve, its a good hobby!

Imagine the radio signal traveling down the wire to the antenna in the same way as an ocean wave. After they travel down to the antenna, the waves bounce back and meet the waves comming to the antenna.

Now what happens when two waves meet? If two waves hit each other, they combine and raise up, and the values below drop farther down (constructive interferrance, they add to each others highs and lows. Another way for waves to meet is a high wave hitting the low section of another wave... so that wave drops down into the valley of the other wave and cancel each other out, in other words the waves combine and are now equal to normal sea level (destructive interferance, or they cancel each other out. where there should be a low spot between waves is now filled with a hi wave comming the other direction, so they cancel each other out and there is no more wave.

Too high of a SWR means that there that the refletive waves are timing up just right so they start to cancel out often, reducing the amount of good waves that can be used to convey the signal to the antenna. instead of a fluid wave motions passing each other in good timing, instead you get segments where the water height stays the same levels all the time, the waves seem to "stand".

http://leiferlingsson.files.wordpress.com/2008/07/standing_waves_400x300.jpg

Heres a good picture to reference, the green line is the normal water level. imagine the two blue waves you see travling from left to right. there is a blue wave, then the valley between the waves on the bottom exposing the sea floor, then the another blue wave. The red wave is comming back the other way, and you see to valleys and just 1 wave. The aligntment is so that, its waves are meeting the other waves exactly where its valleys should be. The net result is regular sea level... (just remember that on an ocilliscope where you could see the electric waves youd see that entire shape, not a flat sea level line, that never moved or oscillated, they would just seem to "stand there".)

heres a website that has a gread moving visual thats how it works:

http://www.rmcybernetics.com/science/physics/electromagnetism2_standing_waves.htm

Thank you for the replys! Makes sense... I'm still waiting on my antenna books, I have $2.15 in my account right now so they have to wait till payday... I did in the meantime find some pdf Army field communications manual that has some very good info on such things, pretty easy read too!

Why would there be an extra reflector at the end and be a circle? couldnt they get away with just having a single pole at the end of the 4 branchs already on the antenna, or does that enable the cicular polarization sensitivity?

Hey all, I've seen a few videos online of people using the HAM satelites and I'm really intrigued! I see they almost all have been using hand held yagis that they rotate back and fourth from horizontal to verticale position to better match the polarization of the satelite during its rise and fall in the sky, and second, they slowly decrease then increase the recieve frequency to match the doppler affect. (ps. I'm not to great of an antena person just yet, my ARRL books are on the way!)

Now, I've seen pictures of military antennas and even some "civilian" antennas such as these:

http://images.monstermarketplace.com/1-stop-tactical-gear/trivec-av2055-3-miniature-coat-pocket-high-gain-satcom-antenna-300x300.jpg

or

http://olive-drab.com/images/elect_anpsc5_375.jpg

Now, the first one looks like a yagi that has both vertical and horizontal pieces, and a circular piece at the rear... and the other has a single center cross and the circular piece at the rear.

Could someone explain to me what makes these different compared the a handheld yagi? Am I right in assuming that they are basically 3 antennas in one, being 2 yagi stle but one in each polarization, and then a single circular one at the rear? If so, how about that single piece cross... is that just like having 2 dipols and a ciruclar at the rear?

Would either of these types be better to build/buy for ham sat use, since they are set to already be circularly polarized?

Yea looks like the Motorolla system is an audible version of CTCSS. I had the idea to set a CTCSS for the first tone to at least block any dispatch that didn't share the same first tone (or second if there were too many) but I forget CTCSS stops at below audio. I found the audio values though if anyones curious... the dispatch uses one frequency but depending on what town they are calling, they send out a 5 second burst of 2 audible tones, the first for 2 seconds, the second for 3 seconds. In my case, my towns first tone is 1232hz and second is 643hz. If you listen to the frequency you will hear the tones, just flat tuning fork type alert noises... but each pager is set so when it hears that signal, it opens the squelch to listen to the frequeny for a set period of time then goes back into mute until it hears those specific notes again. CTCSS only goes from 67hz to 254hz... so my idea of using a single tone open option woudlnt work, and ALSO because its only sent at the beginning of a transmission, and not as a subtone for the duration of the broadcast like with CTCSS... so youd also have to program the CTCSS function in the radio to also open for a set period of time after hearing the tone like a DCS system or this motorola system. I'm guessing though that this is either impossible because they range is present because of the actual hardware that makes up the radio, or is hard programmed into the radio operating software.


buuut theres still hope perhaps that someone somewhere makes a radio that has this feature built in already?

I have a Wouxun UV6D that I usually leave in dual channel mode and scan the county dispatch channel on 1 and my fav repeater on the other. Problem is, that its a county line... I'm really only interested in hearing my town's dispatchs... but I am not to familiar with how tones work for the paging system. I gave it a once over on wiki (pretty sure our city uses motorolla monitor system pagers)

it looks like the pagers are just scanners that squelch out until opened by an AUDIO tone (please correct me if I'm wrong, a DTMF maybe?) instead of a continusouly broadcasted subtone like one would use to access a repeater... then stays open for a set number of minutes as programmed then back in standby until the audio tone is heard again. Now I assume repeaters listen for subtones before transmitting in the same way pagers do for opening squelch... is that an accurate comparrison? if so, I'm guessing that my wouxun can be set up to ignore incomming audio unless its the correct tone (making it a fire pager)? Are there any HT hams that have this feature if not?

I don't currenlty have the hardware to set up APRS via radio, so I've been using my Droid phone with APRSDroid software that uses the GPS data to upload over the phones 4G internet connection.

Now, I have a netbook and an inverter so I can have it in my car, which has a USB gps dongle, along with Windows 7 and Kubunutu OS's on dual boot, and it can tether through my phone. Is there any software out there that is like APRSdroid that can take GPS data and upload position reports through the internet? Most of the software I've found on google viewers only, or upload via TNC or speaker output connection to a physical radio.

Thanks all!

Cool, thanks for all the responses, alot of good info and links to help research

Curious, I always see pictures in Iraq or Afg or where of our boys over there in thier hummers and M1's, and they have seemingly GIANT antennas on those things, when I see them on the road sometimes they are folded forward from the rear of the mount, all the way the the hood it seems. I'm assuming its rather low relitive freq, but anyone out there have an idea what they use in terms of hardware, frequencies, modulation methods etc?

Hey all, I have a firestick cb antenna mounted on my spare tire carrier, and it sticks up high enough to whck a good amount of thigns in my area lol... anywho, I purchased a spring for it so it could bend back an fourth a good deal under load to prevent the fiberglass from snapping... but i get horrible swr once I put it on. the antenna has an adjustable tip screw, but its only maybe an inch long, and the spring is nearly 4"s... is it unusable with this antenna then? or is there something i can put in line to fix it beyond cutting the antenna length?

email this guy, maybe he has one that'll work?

http://www.g4hfq.co.uk/index.html