We report the estimation of the Maximum Usable Frequency of F2-layer for 3000 km circuit ($\mathit{MUF}\left(3000\right)F2$) using Earth-ionosphere geometry. The study is based on the assumption that $h\prime F2$ may replace $\mathit{hmF}2$ to estimate $M\left(3000\right)F2$. The monthly hourly medians of $f_{o}F2,h\prime F2$, and $M\left(3000\right)F2$ are extracted for Karachi (geog. coord. 24.9$°$ N, 67.3$°$ E) & Multan (30.2$°$ N, 71.5$°$ E) during 1996, 1992, & 1989 representing low, moderate & high solar activity years, respectively. The $\mathit{MUF}\left(3000\right)F2$ estimated using spherical geometry shows large deviation and greater Root Mean Square Error values (RMSE $>$ 4 MHz) on comparison with $\mathit{MUF}\left(3000\right)F2$ observed from ionosonde. In order to reduce the error, linear regression analysis technique is used and applied on independent data set of years 1995, 1993 and 1991 representing low, moderate and high solar activity to compute corrected $\mathit{MUF}\left(3000\right)F2$, respectively. It is found that corrected MUF is in good agreement with observed MUF decreasing RMSE to less than 2.0 MHz for the stations and years under study. The results of this study would be helpful in MUF estimation using $h\prime F2$ and also in improving radio services for smooth HF communication.

我们报告了 3000 公里电路的 F2 层最大可用频率的估计（$\mathit{MUF}\left(3000\right)F2$) 使用地球-电离层几何。该研究基于以下假设$H\prime F2$ 可以代替 $\mathit{氢氟酸}2$ 估计 $米\left(3000\right)F2$. 每月的每小时中位数$F_{○}F2,H\prime F2$， 和 $米\left(3000\right)F2$ 提取卡拉奇 (geog. coord. 24.9$°$ 否，67.3$°$ E) & 木尔坦 (30.2$°$ 否，71.5$°$E) 1996、1992 和 1989 年，分别代表低、中和高太阳活动年。这$\mathit{MUF}\left(3000\right)F2$ 使用球面几何估计显示大偏差和更大的均方根误差值 (RMSE $>$ 4 MHz) 与 $\mathit{MUF}\left(3000\right)F2$从离子探空仪上观察到。为减少误差，对1995、1993、1991年代表低、中、高太阳活动的独立数据集采用线性回归分析技术，计算修正后的误差。$\mathit{MUF}\left(3000\right)F2$， 分别。发现校正后的 MUF 与观察到的 MUF 非常一致，将所研究的台站和年份的 RMSE 降低到小于 2.0 MHz。本研究的结果将有助于 MUF 估计使用$H\prime F2$ 以及改善无线电服务以实现顺畅的 HF 通信。