DX reciprocity?

Discussion in 'General Technical Questions and Answers' started by Pushraft, Nov 20, 2008.

Thread Status:
Not open for further replies.
ad: L-HROutlet
ad: l-rl
ad: L-MFJ
ad: abrind-2
ad: Subscribe
ad: Left-3
ad: Left-2
  1. Pushraft

    Pushraft Banned

    I dont have my antenna book near me but I thought the F2 layer was up around 250 miles. I believe the F1 and F2 layers combine at night to form a single F layer which is lower than that. It is not really critical as far as absolute distance away from the surface because as stated previously using trig, since the launch angle up to there is frequenty very low (20 degrees or so), the extra distance is not much at all. So for every 1000 terrestrial miles, it may be 1100 total skip miles if I am not mistaken. That is misleading because the signal has to go up 200 or so miles and back down 200 or so miles but that only adds about 100 miles to the total distance, not 400 miles. How about that? Trig is "cool".
     
  2. AB1GA

    AB1GA Ham Member QRZ Page

    Height of F layer of the ionosphere is broad, from about 100-300 miles.

    During high solar flux two distinct layers are formed during the day, and merge again at night.

    Reference: General Class license manual, not most recent version.
     
  3. Pushraft

    Pushraft Banned

    Just think, without those reflective layers, DX as we know it would not exist. We would have to find some other way like bouncing a signal off the moon or a satellite. We are very lucky we have an ionosphere that is RF reflective even though it is not "perfect". I am used to talking a few miles on "walkie talkies" so being able to hear WWV in Colorado at about 1500 miles away is somewhat of a thrill for me.

    I just hope that when I get my ticket, my weak attic dipole can make some decent contacts and not just the "big guns" but I am counting on the DX reciprocity phenomenon to work in my favor. That is, I will try to get a "free lunch" off of someone elses giant beam 100+ feet up even though my attic dipole is "crap" by comparison.

    I will be inquiring about VECs soon and plan on getting my license sometime in 2009. 2008 is a study year for me and I need to "bone up" on more theory. I think I am getting better as you can see from my posts. That F2 later stuff I did off the top of my head. That was in my Rat Shack book (hey he even got that term correct. This guy is getting serious!).

    73 (impressive)
     
  4. K7MH

    K7MH Ham Member QRZ Page

    Got news for ya Pushrod!!:D:D:D:D
    We'll let you discover meteor scatter for us though!:rolleyes:
     
    Last edited: Nov 24, 2008
  5. KL7AJ

    KL7AJ XML Subscriber QRZ Page

    Actually, when the F1 and F2 layers merge, it's at a HIGHER altitude. This is why the bands "go long" at night.
     
  6. Pushraft

    Pushraft Banned

    F, F1, and F2 layers

    According to the ARRL book Edition 18 Chapter 23 page 16, we have this:

    "At night the F1 layer disappears and the F2 layer height drops somewhat".

    My Rat Shack book also shows the F1 and F2 layers combining at night into the F layer and dropping in height below that of the F2's height. It has F at 90-250 miles, F1 at 90-150 miles, and F2 at > 250 miles.

    Back to ARRL book. The height of these layers is dependant upon many things including where on Earth they are such as close to the equator or not and many other factors. Makes for interesting reading.

    Also the ARRL book answered on of my questions about what happens when a single hop and a double hop both reach the destination. It states that the one-hop signal will generally be from 7 to 10 dB stronger.
     
  7. N9VO

    N9VO XML Subscriber QRZ Page

    Ionospheric Layers:

    There are four distinct layers of the ionosphere which are designated d, e, f1 and f2. The height, thickness and intensity of ionization for each of the layers is measured by transmitting r-f pulses vertically into the ionosphere and then receiving the returned pulse. The echo time indicates height of the ionospheric layer; the strength of the received signal indicates thickness of the layer. When pulses of various r-f frequencies are transmitted, a frequency will be found above which the vertical wave will not be refracted back to earth. this frequency, called the critical frequency, indicates the extent of ionization. The higher the critical frrequency, the greater the ionization. Since the ionospheric layers are caused chiefly by ultraviolet light emitted from the sun, their height and thickness change with the season and time of day.

    The d layer exists only in the daytime. Very little sky-wave refraction is obtained from this layer, and there is pronounced absorption effect at frequencies below 2 mc. The e layer exists only during daylight hours at a height of about 55 to 85 miles. The f1 layer exists at a height between 85 and 155 miles during the daylight hours. When the sun sets, the f1 layer merges with the next higher ionized layer, the f2 layer. The f2 layer is the most useful layer for sky-wave transmission because it exists during the night as well as the day. this layer occurs between 90 and 150 miles above the earth at night during all seasons. In the northern hemisphere, the f2 is somewhat higher in the summer than in the winter during the day, extending between 90 and 180 miles in altitude.

    Info courtesy of the US Navy Communications Technican course of long long ago!
     
  8. AG3Y

    AG3Y Guest

    "I will be inquiring about VECs soon and plan on getting my license sometime in 2009. 2008 is a study year for me and I need to "bone up" on more theory. I think I am getting better as you can see from my posts. That F2 later stuff I did off the top of my head. That was in my Rat Shack book (hey he even got that term correct. This guy is getting serious!)."

    Push, you are just making it WAAAAYYY TOOOOO HARD for yourself ! ! !
     
  9. Pushraft

    Pushraft Banned

     
  10. N4CR

    N4CR Ham Member QRZ Page

    This isn't open to much debate because it's not defined as distance. DX means 'Not in my country'. That means that Buffalo, NY to Toronto, ON is officially DX in almost every entity that grades confirmed contacts for inclusion in awards.

    DX in general public vernacular may mean distance, but in Ham Radio, it means 'Not in my country'. This means that for many Europeans, DX to two dozen countries is easier than typical transmissions from Florida to Seattle.

    Doesn't matter if it makes sense, it's the way it is.
     
Thread Status:
Not open for further replies.

Share This Page