I am using a Pixie transceiver, giving 1 W power and 7 MHz frequency. A 40-meter band dipole antenna, providing 5 dBi gain at high angles, has been designed and connected at the output of the circuit to transmit. We are using the concept of reflection from the ionosphere to receive a signal at a distance of 200 km from the transmitter. Our antenna is in the inverted-V configuration. We have designed the same antenna for the transmitter as well as the receiver.
First of all, we have tested it for almost a 15-meter region. We transmitted the signal from the same Pixie transceiver from the transmitter then to receiver and successfully received that signal at the receiver. Now, we tried to perform the same experiment by keeping a distance of 15 km between transmitter and receiver. We received only noise and the original signal was not received.
What modifications are required in my overall system as explained above so that we can receive our signal at a longer range?
Note: Keep in mind I want to receive skywaves, so for that reason, the actual distance is the distance from the earth to the ionosphere and then back to earth.