This
https://www.amazon.com/dp/B083XQY2ZP/ref=cm_sw_r_apan_glt_i_ZGBA241BAQV3ZJJ6NF57
inside of some PVC capped at both ends actually works surprisingly well for me given the cost.
Acxico 1Pcs ADS-B 1090MHZ PCB Antenna ANT https://www.amazon.com/dp/B083XQY2ZP/ref=cm_sw_r_cp_api_glt_fabc_Y5H37E73VN74093WX4AN?_encoding=UTF8&psc=1
Been working great for me. Very inexpensive.