LZ1AQ - Personal Home Page

LZ1AQ Projects

Full information about my projects can be obtained from the following pages:

LZ1AQ Articles Organized by Topics (Links)

• Short Vertical Receiving Antenna. Experiments with a Capacitive Hat
  (New) (Jul 20232)
• Electromagnetic noise level measurements on 3.5 MHz HF band during car drive
• Using ferrite E-cores for baluns
• Integrating Software Defined Radio (SDR) and a Standard Transceiver. Revision 3
• Active Wideband Directional Antenna with Vertically Polarized Small Loop and Small Dipole
• A Simple Dipole For 2m Band
• Impact of the Height Above the Ground to the Receiving Performance of a Small Wideband Magnetic Loop
  
• 2-element Single Mast Wire Beam with 4 Switchable Directions - Adddendum
• 2-element Single Mast Wire Beam with 4 Switchable Directions
• A Simple and Very Sensitive RF Current Sensor
• Spreadsheet to calculate parameters of small RX loop WLoop Calc
• Impacts from Non-resonant Conductive Objects on RX Directional Antennas
• Impact of Resonant TX antennas on the Radiation Pattern of RX Directional Antennas. Detuning of TX Antennas
• A Periodic Switching Technique to Compare Receiving Antenna Performance in the Presence of Strong Fading
• Horizontally mounted small active receiving antennas
• Diversity Reception with a Modified SDR Receiver and Small Active Antennas
• Receiving with wideband small active loops in NDB band (250 to 500 KHz)
  (April 2015)
• Time Delay and Frequency Response of the Filters in Perseus SDR Receiver
  (January 2015)
• Receiving Phased Array with Small Electric or Magnetic Active Wideband Elements. Experimental Performance Evaluation.
  (December 2013)
• Single Tone Measurements of Nonlinear Distortions in Wideband RF Amplifiers
  (February 2014)
• Experimental Comparison of Small Wideband Magnetic Loops
  (Last Rev. August 2013)
• Wideband Active Small Magnetic Loop Antenna. Protection from Strong Electromagnetic Fields
  (Last Rev. March 2011)
• Wideband Active Small Magnetic Loop Antenna
  (Last Rev. June 2011)
• Measurements of Signal Time Delays in Several SDR Programs
  (Last Rev. Oct. 2011)
• Preamplifier and Bandpass filter for SDR from 1.8 to 18 MHz
  (Last Rev. Dec 2008)
• Integrating Software Defined Radio (SDR) and a Standard Transceiver. Revision 2
  (Last Rev. Nov. 2010)
• Integrating Software Defined Radio (SDR) and Standard Transceiver
  (Last Rev. Feb. 2008)
• Very Weak Signal Reception with Small Magnetic Loop Antenna
  (Last Rev. Jan. 2010)

Biography

Chavdar Levkov (b.1949 in Sofia, Bulgaria). First crystal detector radio at the age of 10. First QSO in 1963. LZ1AQ call sign obtained in 1969. M.Sc. degree in telecommunications from Sofia Tech. University in 1973. In 1973 designed a simple CW/SSB transceiver which become widely popular among Bulgarian amateurs. More than 200 copies were built. Worked in the field of biomedical engineering from 1976 in the Institute of Biomedical Engineering and the Medical Academy in Sofia. Obtained Doctor of Science title in 1987 in the field of Technical Electrocardiology. Assoc. Professor from 1990. From 1991 founder and C.E.O. of a small firm for design and production of electrocardiological equipment. The radio has been his first love and hobby. Married – wife Mariana, sons Lev (LZ1ACD) and Chavdar jr. (LZ1ABC).

Contact: lz1aq@abv.bg